Effects of caffeine: A Synthesis of Findings from 90 Studies

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Original Abstract of the Article

Major Research Findings

Caffeine has been shown to have various effects on the human body, including improvements in muscle strength, cognitive function, and alertness. 79 78 72 A study investigating the placebo effect of caffeine on muscle strength found that caffeine improved peak concentric force in the knee flexors and extensors. 79 However, the study also found that the expectation of caffeine's effects could actually negatively impact performance. This suggests that factors like motivation and personality can play a role in how caffeine affects individuals. 79 Another study found that caffeine can enhance attention and conflict monitoring, while also potentially offsetting the effects of alcohol on cognitive processes. 78 It's important to note that the impact of caffeine on performance is not always positive, and individual variability exists. 88 Additionally, caffeine consumption combined with sleep deprivation can negatively affect glucose homeostasis. 82 These studies highlight the complex and varied nature of caffeine's effects on the human body.

Benefits and Risks

Benefits Summary

Caffeine can enhance cognitive function, improve alertness, and potentially enhance athletic performance. 79 78 68 Caffeine may also help alleviate fatigue and improve mood. 60 Furthermore, caffeine may have potential benefits for those trying to reduce alcohol consumption. 78

Risks Summary

Overconsumption of caffeine can lead to adverse effects such as insomnia, anxiety, heart palpitations, digestive problems, and dehydration. 52 40 Caffeine can also elevate blood pressure, potentially exacerbating existing cardiovascular conditions. 70 41 Furthermore, caffeine can be addictive and withdrawal symptoms may occur when consumption is reduced. 32 It's essential to be mindful of these potential risks and consume caffeine responsibly.

Comparison Across Studies

Similarities

Many studies consistently demonstrate caffeine's ability to enhance cognitive function, improve alertness, and potentially boost athletic performance. 79 78 68 Caffeine also seems to help alleviate fatigue and improve mood. 60 However, it's crucial to acknowledge that the effectiveness of caffeine varies greatly among individuals and is influenced by factors such as dosage and timing of consumption. 88 87

Differences

The impact of caffeine on athletic performance is not universally consistent. 68 87 This variability could be attributed to differences in exercise type, intensity, training status of participants, and caffeine dosage and timing. Additionally, studies have yielded conflicting results regarding caffeine's ability to counter the effects of alcohol. 78 66 This inconsistency may stem from variations in the type and amount of alcohol used, as well as individual differences in alcohol tolerance. The complex nature of caffeine's effects necessitates a comprehensive understanding of the research findings.

Consistency and Contradictions

Research consistently shows that caffeine's effects can vary significantly between individuals, and are influenced by factors such as dosage and timing of consumption. 88 87 Caffeine's impact on the body is complex, as it influences neurotransmitter and hormone levels, making it difficult to definitively pinpoint all the mechanisms involved. This complexity can lead to discrepancies in research findings. For instance, some studies show caffeine enhancing athletic performance, while others show it hindering performance. 68 87 These contradictions are likely due to variations in research methodology and participant characteristics.

Considerations for Real-World Application

While caffeine can potentially enhance cognitive function, improve alertness, and boost athletic performance, 79 78 68 its effects can vary greatly from person to person. Therefore, it's crucial to be mindful of individual sensitivity and health conditions. Overconsumption of caffeine can lead to negative consequences such as insomnia, anxiety, heart palpitations, digestive problems, and dehydration. 52 40 Furthermore, caffeine can elevate blood pressure, potentially exacerbating cardiovascular issues. 70 41 Responsible caffeine consumption requires individual awareness and caution.

Limitations of Current Research

There are still many unanswered questions regarding the effects of caffeine on the human body. 88 87 For example, we need to understand how caffeine influences neurotransmitter and hormone release, the reasons for individual variability in response to caffeine, and the long-term impacts of caffeine consumption. Further research is necessary to address these unanswered questions.

Future Directions

To gain a more thorough understanding of caffeine's effects, research efforts should be directed towards exploring various aspects. 88 87 This includes investigating how caffeine affects neurotransmitter and hormone release, identifying the factors contributing to individual variability in caffeine response, and examining the long-term consequences of caffeine consumption. It's also essential to study the potential interactions between caffeine and other drugs. 31 This research will help us better understand the safe consumption of caffeine and its optimal applications.

Conclusion

Caffeine can potentially enhance cognitive function, improve alertness, and boost athletic performance. 79 78 68 However, the effectiveness of caffeine can vary significantly between individuals and is influenced by factors such as dosage and timing of consumption. 88 87 It's essential to be mindful of individual sensitivity and health conditions when consuming caffeine, and to avoid overconsumption. Moreover, caffeine can interact with other drugs. 31 Before consuming caffeine, it's recommended to consult with a healthcare professional.

Keywords
Benefit Keywords
No negative effects for caffeine-familiar
3
Improves attention
Increases alertness
5
Alertness improvement
Auditory vigilance enhancement
9
Caffeine Effects
Improved Attention
10
Improved performance on difficult tasks
11
Mood improvement
Vigilance improvement
13
Alertness increase
Headache decrease
Tiredness decrease
14
Improved cognition
Improved mood
17
Caffeine effects on cognition
18
Decreased sleep tendency
19
Mental performance enhancement
20
Caffeine awareness
21
Caffeine awareness
Increased alertness
22
Cognitive performance
23
Arousal regulation
Caffeine benefits
Improved recall
27
Enhanced performance
Improved mood
28
Improved cognitive performance
Improved motor performance
29
Improved mood
Improved performance
30
None reported
31
Asthma treatment
33
Alerting effects
Improved reaction time
Less sleep disruption
Sustained performance
34
Improved mood
Increased alertness
35
Improved performance
Improved vigilance
36
Mood improvement
38
Asthma treatment
39
Improved performance
Increased mental alertness
43
Cognitive enhancement
44
Cognitive enhancement
45
Improve cognitive performance
Improve mood
46
Enhanced performance
Improved mood
48
Stimulatory effect
49
Increased arousal
50
Alertness improvement
Information encoding enhancement
Reaction time improvement
51
Improved alertness
Improved performance
53
Blood pressure reduction
Cognitive performance
Relaxation
56
Improved cognitive function
Reduced mental fatigue
57
arousal modulation
58
Mental fatigue reduction
Task performance improvement
59
Cognitive enhancement
60
Subjective activation
62
Improved cognitive ability
Improved endurance performance
63
Alertness
Performance efficiency
65
Improved performance
67
Exercise performance enhancement
68
Improved attention
Improved memory
69
Caffeine tolerance
70
Cognitive function
72
Counteracts alcohol-induced alertness drop
73
Concentration enhancement
Memory enhancement
Physical performance improvement
76
Improved attention
Improved executive updating
Reduced fatigue
77
Conflict monitoring
78
Muscle strength
79
Cognitive function enhancement
80
Improved performance
Treatment for apnea
81
Exercise performance enhancement
85
Improved cognition
Improved mood
86
Improved athletic performance
87
Exercise performance
88
Cognitive enhancement
Mood enhancement
89
Risk Keywords
Alcohol and caffeine effects vary by gender
1
Detrimental to caffeine-naive
3
Caffeine and stress
4
Caffeine-related symptoms
6
Caffeine accumulation
7
Hypertension
Increased stress response
8
Caffeine tolerance
9
Increased anxiety
11
Anxiety
12
Anxiety
15
Caffeine deprivation risk
16
Increased tension
22
Anxiety
Muscular tension
23
Headache
24
Hip fracture
Osteoporosis
25
Craving
Hunger
26
Increased blood pressure
Increased fatigue
28
Anxiety
Excitement
Irritability
Nausea
Nervousness
Palpitations
Restlessness
Tension
29
Fatigue
30
Increased clozapine exposure
31
Caffeine withdrawal
Cerebral blood flow
EEG changes
32
Sleep onset disruption
Sleep quality disruption
34
Autonomic stimulation
35
Side effects
36
Insulin resistance
40
Caffeine tolerance incomplete
Mood impairment
41
Caffeine tolerance
42
Caffeine withdrawal
45
Adverse effects
Increase blood pressure
46
Impaired sleep
Reduced sleep depth
47
Withdrawal effects
48
Headache
57
Deeper fatigue
59
caffeine withdrawal
withdrawal reversal
61
Ineffective for sleep loss
64
Neuropsychological effects
66
Decreased performance
68
Cardiovascular changes
70
Alcohol related harms
71
No effect on alcohol-induced performance
73
Placebo effect
75
Caffeine dependence
Caffeine intoxication
76
Cognitive impairment
78
Expectancy
Motivation
79
Sleep disruption
81
Increased insulin
82
Acute effects
Behavioral effects
Bone status
Cardiovascular toxicity
Reproductive and developmental effects
83
Jittery ratings
86
Slight decrease in performance
87
Anxiogenic effects
Stimulant effects
90
Literature analysis of 90 papers
Positive Content
62
Neutral Content
8
Negative Content
20
Article Type
81
3
6
6
90
1.

The effects of alcohol and caffeine on concentration test performance.

Author: KeuchelI, KohnenR, LienertG A

Alcohol and caffeine effects vary by gender

A study of 28 students (7 in each group) found that alcohol and caffeine affected concentration differently based on gender. In men, both alcohol and caffeine decreased concentration, and when combined, their effects were synergistic, meaning they amplified each other. In women, alcohol and caffeine increased concentration, but when combined, their effects were antagonistic, meaning they canceled each other out.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Controlled Clinical TrialA clinical trial that evaluates the effectiveness of a treatment by comparing a group that receives the intervention with a group that receives a placebo or standard treatment.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

2.

[Multichannel EEG spectral analysis of the caffeine effect].

Author: KünkelH

Coffee and caffeine solution produced a significant reduction in theta-amplitude, dominant theta-frequency, and theta-frequency-variation in EEG studies.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Comparative StudyResearch that compares multiple groups/interventions to determine differences/similarities in outcomes/characteristics.
English AbstractA summary of a research paper/publication written in English for a wider audience.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : German

3.

Effect of caffeine on motor performance by caffeine-naive and -familiar subjects.

Author: JacobsonB H, Thurman-LaceyS R

No negative effects for caffeine-familiar
Detrimental to caffeine-naive

Caffeine had detrimental effects on selected manipulation skills in caffeine-naive women but not in caffeine-familiar women.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

4.

Cardiovascular responses to the combination of caffeine and mental arithmetic, cold pressor, and static exercise stressors.

Author: FranceC, DittoB

Caffeine and stress

Caffeine combined with stressor tasks, such as mental arithmetic, cold pressor, and static exercise, significantly increased blood pressure and finger temperature in healthy males.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, Non-U.S. Gov'tResearch funding provided by government agencies outside the United States.

Language : English

5.

A comparison of the central nervous system effects of caffeine and theophylline in elderly subjects.

Author: YuG, MaskrayV, JacksonS H, SwiftC G, TipladyB

Improves attention
Increases alertness

This study compared the effects of caffeine and theophylline to a placebo on cognitive performance and subjective feelings in 20 healthy older adults. Caffeine significantly improved performance on a continuous attention task compared to both placebo and theophylline. Participants also reported feeling more alert, energetic, and interested on caffeine compared to placebo or theophylline. While both drugs reached similar blood levels, caffeine appeared to be a more potent stimulant.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Comparative StudyResearch that compares multiple groups/interventions to determine differences/similarities in outcomes/characteristics.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

6.

Efficacy of caffeine versus expectancy in altering caffeine-related symptoms.

Author: ChristensenL, MillerJ, JohnsonD

Caffeine-related symptoms

The study found no significant effect of caffeine or expectancy on caffeine-related symptoms after controlling for the increased probability of Type I error. This suggests that previous reports of subjective caffeine effects may have been influenced by methodological limitations.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

7.

Effects of caffeine with repeated dosing.

Author: DenaroC P, BrownC R, JacobP, BenowitzN L

Caffeine accumulation

This study examined the effects of regular caffeine consumption on 9 healthy individuals. While the body developed tolerance to caffeine's effects on blood pressure, heart rate, and blood sugar levels, high doses of caffeine (equivalent to 6-11 cups of coffee daily) still showed a trend towards increasing levels of norepinephrine (a hormone associated with stress) and free fatty acids. This suggests that regular high-dose caffeine intake may have persistent effects on the body even after tolerance develops.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, Non-U.S. Gov'tResearch funding provided by government agencies outside the United States.
Research Support, U.S. Gov't, P.H.S.Research funding provided by the Public Health Service (PHS).

Language : English

8.

The influence of user status and anxious disposition on the hypertensive effects of caffeine.

Author: JamesJ E

Hypertension
Increased stress response

Caffeine was found to produce significant elevations in systolic and diastolic blood pressure, especially in males. In a randomized double-blind crossover study of 60 normotensive subjects, caffeine produced hypertensive effects that were additive to the pressor effects of stress and anxiety.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, Non-U.S. Gov'tResearch funding provided by government agencies outside the United States.

Language : English

9.

Effects of caffeine on alertness.

Author: Zwyghuizen-DoorenbosA, RoehrsT A, LipschutzL, TimmsV, RothT

Alertness improvement
Auditory vigilance enhancement
Caffeine tolerance

Caffeine improves alertness and performance, but tolerance develops rapidly with repeated use.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

10.

Acute autonomic nervous system effects of caffeine in prepubertal boys.

Author: ZahnT P, RapoportJ L

Caffeine Effects
Improved Attention

Caffeine was tested in 19 prepubertal boys for its effects on autonomic activity. Caffeine increased skin conductance responses and decreased heart rate and motor activity at a lower dose. It also showed evidence of improved attention.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

11.

Effects of caffeine on mood and memory.

Author: LokeW H

Improved performance on difficult tasks
Increased anxiety

A double-blind study of caffeine on mood and memory tasks found that 200 mg of caffeine improved performance on more difficult tasks. Caffeine also reduced boredom and relaxation, but increased anxiety, tenseness, and nervousness. Regular caffeine users showed improved memory, especially at the beginning of word lists.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

12.

Plasma adenosine levels: measurement in humans and relationship to the anxiogenic effects of caffeine.

Author: BoulengerJ P, SalemN, MarangosP J, UhdeT W

Anxiety

Caffeine did not affect plasma adenosine levels in eight healthy volunteers who were given placebo or three doses of caffeine (240, 480, and 720 mg). Caffeine's effects on anxiety were related to changes in plasma caffeine levels but not plasma adenosine levels.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

13.

The effects of caffeine and aspirin on mood and performance.

Author: LiebermanH R, WurtmanR J, EmdeG G, CoviellaI L

Mood improvement
Vigilance improvement

Caffeine (64 mg) combined with aspirin (800 mg) significantly improved vigilance performance and increased self-reported efficiency compared to placebo or aspirin alone. This dose of caffeine alone also significantly increased vigilance and decreased reaction time. No adverse effects of caffeine were detected.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Controlled Clinical TrialA clinical trial that evaluates the effectiveness of a treatment by comparing a group that receives the intervention with a group that receives a placebo or standard treatment.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

14.

The psychopharmacological and electrophysiological effects of single doses of caffeine in healthy human subjects.

Author: BruceM, ScottN, LaderM, MarksV

Alertness increase
Headache decrease
Tiredness decrease

Caffeine produced dose-related effects on physiological and psychological measures, including an increase in skin conductance level and self-rating of alertness.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

15.

Effects of caffeine use and ingestion on a protracted visual vigilance task.

Author: LokeW H, MeliskaC J

Anxiety

College students who are high caffeine users (HCU) were found to perform worse on a visual vigilance task than low caffeine users (LCU). They made fewer hits, more false alarms, and responded faster. Caffeine administration did not have a significant effect on the task performance. Male subjects were more anxious after the experiment.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, Non-U.S. Gov'tResearch funding provided by government agencies outside the United States.

Language : English

16.

Effects of caffeine deprivation on complex human functioning.

Author: StreufertS, PogashR, MillerJ, GingrichD, LandisR, LonardiL, SeversW, RoacheJ D

Caffeine deprivation risk

Caffeine deprivation caused discomfort and decreased managerial effectiveness in a study of 25 managers. Cognitive effectiveness during complex task performance was diminished, but strategic performance requiring high cognitive effort was unaffected.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, U.S. Gov't, P.H.S.Research funding provided by the Public Health Service (PHS).

Language : English

17.

Effects of caffeine on cognition and mood without caffeine abstinence.

Author: WarburtonD M

Improved cognition
Improved mood

Low doses of caffeine improved attention, problem-solving, and delayed recall in healthy people. It also significantly increased feelings of clearheadedness, happiness, and calmness while decreasing tenseness.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

18.

Mental effects of caffeine in fatigued and non-fatigued female and male subjects.

Author: LindeL

Caffeine effects on cognition

Caffeine had a mixed effect on cognitive performance, depending on gender and task complexity. Women experienced negative effects on complex tasks, while men showed positive effects.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

19.

The effects of caffeine on simulated night-shift work and subsequent daytime sleep.

Author: MuehlbachM J, WalshJ K

Decreased sleep tendency

Caffeine can decrease physiological sleep tendency during night shifts, but does not affect performance. Caffeine consumption did not show a discontinuation effect on sleep latency.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Comparative StudyResearch that compares multiple groups/interventions to determine differences/similarities in outcomes/characteristics.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

20.

Acute dose-effect relationships of caffeine and mental performance, EEG, cardiovascular and subjective parameters.

Author: HasenfratzM, BättigK

Mental performance enhancement

This study investigated the dose-effect relationship of caffeine on mental performance, cardiovascular, EEG, and mood parameters in female coffee drinkers. Caffeine showed heterogeneous dose-effect relationships, with increasing effects observed for some parameters (alpha- and beta-EEG frequencies, anxiety, wakefulness) and negative dose-effect relationships observed for others (RIP processing rate, blood pressure).

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, Non-U.S. Gov'tResearch funding provided by government agencies outside the United States.

Language : English

21.

Discriminative stimulus and subjective effects of theobromine and caffeine in humans.

Author: MumfordG K, EvansS M, KaminskiB J, PrestonK L, SannerudC A, SilvermanK, GriffithsR R

Caffeine awareness

This study investigated theobromine and caffeine discrimination and subjective effects in humans. Five out of seven participants discriminated theobromine at doses ranging from 100 to 560 mg, while all seven discriminated caffeine at doses ranging from 1.8 to 178 mg. Caffeine significantly altered subjective ratings, while theobromine did not.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Comparative StudyResearch that compares multiple groups/interventions to determine differences/similarities in outcomes/characteristics.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, U.S. Gov't, P.H.S.Research funding provided by the Public Health Service (PHS).

Language : English

22.

Do double-blind studies with informed consent yield externally valid results? An empirical test.

Author: KirschI, RosadinoM J

Caffeine awareness
Increased alertness
Increased tension

This study found that instructions regarding caffeine consumption significantly impacted subjective feelings of alertness. Participants who knew they were consuming caffeine reported greater tension. Caffeine also increased alertness and systolic blood pressure. This challenge the external validity of typical double-blind studies, where participants are aware of the possibility of a placebo.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

23.

Caffeine and smoking: subjective, performance, and psychophysiological effects.

Author: PritchardW S, RobinsonJ H, deBethizyJ D, DavisR A, StilesM F

Cognitive performance
Anxiety
Muscular tension

Caffeine increases muscular tension and anxiety, while smoking improves cognitive performance and increases heart rate. Both substances have different effects on brain activity as measured by EEG.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

24.

Cardiovascular, behavioral, and subjective effects of caffeine under field conditions.

Author: HöferI, BättigK

Headache

This study examined the effects of continuous and intermittent caffeine abstinence on physiological and subjective measures. Caffeine abstinence resulted in increased heart rate, decreased motor activity, and subjective changes, while intermittent abstinence led to increased wakefulness.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, Non-U.S. Gov'tResearch funding provided by government agencies outside the United States.

Language : English

25.

Coffee: brew or bane?

Author: ThompsonW G

Hip fracture
Osteoporosis

This literature review examined the effects of coffee and caffeine on various health outcomes. Coffee did not have an appreciable effect on hyperlipidemia, hypertension, ischemic heart disease, or cancer.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Meta-AnalysisA statistical technique that integrates the results of multiple studies to draw more general conclusions about a particular issue.

Language : English

26.

Coffee and alcohol intake as predictors of smoking cessation and tobacco withdrawal.

Author: HughesJ R, OlivetoA H

Craving
Hunger

A study of 105 smokers who received physician advice plus placebo gum and 630 self-quitters found that neither alcohol nor caffeine use before or after quitting smoking predicted relapse or withdrawal symptoms.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, U.S. Gov't, P.H.S.Research funding provided by the Public Health Service (PHS).

Language : English

27.

Effects of caffeine and gender on physiology and performance: further tests of a biobehavioral model.

Author: SmithB D, DavidsonR A, GreenR L

Arousal regulation
Caffeine benefits
Improved recall

This study found that habitual caffeine use can increase arousal and improve memory performance. Acute caffeine intake can also increase arousal and reduce habituation to stimuli. These effects were found to be different for men and women.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

28.

Illustrating caffeine's pharmacological and expectancy effects utilizing a balanced placebo design.

Author: LotshawS C, BradleyJ R, BrooksL R

Enhanced performance
Improved mood
Increased blood pressure
Increased fatigue

Caffeine consumption may be governed by both pharmacological and expectancy effects.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

29.

Dose-dependent pharmacokinetics and psychomotor effects of caffeine in humans.

Author: KaplanG B, GreenblattD J, EhrenbergB L, GoddardJ E, CotreauM M, HarmatzJ S, ShaderR I

Improved cognitive performance
Improved motor performance
Anxiety
Excitement
Irritability
Nausea
Nervousness
Palpitations
Restlessness
Tension

This study examined the effects of different doses of caffeine on subjective effects, performance, and electroencephalographic activity. Lower doses of caffeine (250 mg) produced more favorable subjective effects and enhanced performance compared to higher doses (500 mg), which were associated with more unpleasant effects and less performance enhancement.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, U.S. Gov't, P.H.S.Research funding provided by the Public Health Service (PHS).

Language : English

30.

Mood and psychomotor performance effects of the first, but not of subsequent, cup-of-coffee equivalent doses of caffeine consumed after overnight caffeine abstinence.

Author: RobelinM, RogersP J

Improved mood
Improved performance
Fatigue

This study investigated the effects of caffeine on mood and performance in 64 regular caffeine consumers. Caffeine significantly improved mood and performance compared to placebo, particularly improving reaction time and reducing performance decline over time. Interestingly, the study found that one, two, or three doses of caffeine (totalling 86, 172, and 258 mg) were equally effective, suggesting a flat dose-response relationship for caffeine's effects on mood and performance. The study concludes that while caffeine can improve mood and performance, the benefits may not outweigh the downsides of frequent caffeine use, particularly considering the negative effects of caffeine withdrawal.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, Non-U.S. Gov'tResearch funding provided by government agencies outside the United States.

Language : English

31.

Effect of caffeine on clozapine pharmacokinetics in healthy volunteers.

Author: HäggS, SpigsetO, MjörndalT, DahlqvistR

None reported
Increased clozapine exposure

Caffeine in daily doses of 400-1000 mg inhibits the metabolism of clozapine to an extent that might be clinically significant in certain individuals.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, Non-U.S. Gov'tResearch funding provided by government agencies outside the United States.

Language : English

32.

Caffeine withdrawal increases cerebral blood flow velocity and alters quantitative electroencephalography (EEG) activity.

Author: JonesH E, HerningR I, CadetJ L, GriffithsR R

Caffeine withdrawal
Cerebral blood flow
EEG changes

Caffeine withdrawal produced changes in cerebral blood flow velocity and quantitative EEG, which may be related to classic caffeine withdrawal symptoms.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, U.S. Gov't, P.H.S.Research funding provided by the Public Health Service (PHS).

Language : English

33.

Caffeine for asthma.

Author: BaraA I, BarleyE A

Asthma treatment

This review summarizes the evidence for caffeine's potential role as an asthma treatment. Caffeine has pharmacological effects similar to theophylline, an asthma treatment.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
ReviewAn article that critically examines existing research on a particular topic and summarizes the current state of knowledge in the field.
Systematic ReviewA review that systematically collects, evaluates, and integrates relevant research to answer a specific research question.

Language : English

34.

A naturalistic investigation of the effects of day-long consumption of tea, coffee and water on alertness, sleep onset and sleep quality.

Author: HindmarchI, RigneyU, StanleyN, QuinlanP, RycroftJ, LaneJ

Alerting effects
Improved reaction time
Less sleep disruption
Sustained performance
Sleep onset disruption
Sleep quality disruption

Day-long consumption of caffeinated beverages may maintain aspects of cognitive and psychomotor performance throughout the day and evening when caffeinated beverages are administered repeatedly.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

35.

The acute physiological and mood effects of tea and coffee: the role of caffeine level.

Author: QuinlanP T, LaneJ, MooreK L, AspenJ, RycroftJ A, O'BrienD C

Improved mood
Increased alertness
Autonomic stimulation

Caffeine acutely stimulates the autonomic nervous system and increases alertness, but caffeine level is not an important factor in its acute effects.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

36.

Slow-release caffeine: a new response to the effects of a limited sleep deprivation.

Author: LagardeD, BatéjatD, SicardB, TrocherieS, ChassardD, EnslenM, ChauffardF

Improved performance
Improved vigilance
Side effects

Slow-release caffeine (300 mg) effectively maintained a good level of vigilance and performance during limited sleep deprivation, lasting for 13 hours after treatment.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Comparative StudyResearch that compares multiple groups/interventions to determine differences/similarities in outcomes/characteristics.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

37.

Effect of smoking abstinence on the subjective effects of caffeine.

Author: HughesJ R, LiguoriA, DominickA, MacLaughlinM

This study investigated the effect of abstinence from smoking on the subjective effects of caffeine. Abstinence from smoking did not significantly change the effects of caffeine, suggesting that smokers trying to quit do not need to change their caffeine intake.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, U.S. Gov't, P.H.S.Research funding provided by the Public Health Service (PHS).

Language : English

38.

[Experimental study of the effect of acetylsalicylic acid combined with caffeine regarding possible abuse potential].

Author: HüppeA, JankeW

Mood improvement

This study investigated the effects of aspirin and caffeine on mood and cardiovascular parameters in women. Caffeine was found to reduce negative mood, while aspirin had no effect. The combination of aspirin and caffeine did not increase positive mood.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Comparative StudyResearch that compares multiple groups/interventions to determine differences/similarities in outcomes/characteristics.
English AbstractA summary of a research paper/publication written in English for a wider audience.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, Non-U.S. Gov'tResearch funding provided by government agencies outside the United States.

Language : German

39.

Caffeine for asthma.

Author: BaraA I, BarleyE A

Asthma treatment

This is a review of the evidence regarding caffeine's potential role in asthma treatment. Caffeine has a variety of pharmacological effects and is chemically related to theophylline, a drug used to treat asthma.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
ReviewAn article that critically examines existing research on a particular topic and summarizes the current state of knowledge in the field.
Systematic ReviewA review that systematically collects, evaluates, and integrates relevant research to answer a specific research question.

Language : English

40.

Caffeine can decrease insulin sensitivity in humans.

Author: KeijzersGerben B, De GalanBastiaan E, TackCees J, SmitsPaul

Insulin resistance

Caffeine, a common stimulant in beverages, has been hypothesized to reduce insulin sensitivity by increasing catecholamine release and/or blocking adenosine-mediated glucose uptake.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, Non-U.S. Gov'tResearch funding provided by government agencies outside the United States.

Language : English

41.

Central and peripheral effects of sustained caffeine use: tolerance is incomplete.

Author: WatsonJoanne, DearyIan, KerrDavid

Caffeine tolerance incomplete
Mood impairment

Tolerance to caffeine is incomplete, as demonstrated by persistent effects on both peripheral and central mechanisms even after chronic caffeine consumption. While regular caffeine intake may lead to a less pronounced effect on blood vessel dilation and mood, it does not completely eliminate these effects.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, Non-U.S. Gov'tResearch funding provided by government agencies outside the United States.

Language : English

42.

Effects of caffeine on mood and performance: a study of realistic consumption.

Author: BriceCarolyn F, SmithAndrew P

Caffeine tolerance

There is a need for more research on the behavioral effects of realistic patterns of caffeine consumption, as many studies have used large, single doses that do not reflect typical ingestion habits.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Comparative StudyResearch that compares multiple groups/interventions to determine differences/similarities in outcomes/characteristics.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, Non-U.S. Gov'tResearch funding provided by government agencies outside the United States.

Language : English

43.

Effects of caffeine on performance and mood depend on the level of caffeine abstinence.

Author: YeomansMartin R, RipleyTamzin, DaviesLaura H, RustedJennifer M, RogersPeter J

Improved performance
Increased mental alertness

Caffeine reliably improves performance and mental alertness in moderate caffeine consumers who are caffeine-deprived. However, these effects are significantly reduced or eliminated when consumers are no longer deprived, suggesting that the observed effects are primarily due to the reversal of caffeine withdrawal.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Comparative StudyResearch that compares multiple groups/interventions to determine differences/similarities in outcomes/characteristics.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

44.

Cognitive and physiological effects of an "energy drink": an evaluation of the whole drink and of glucose, caffeine and herbal flavouring fractions.

Author: ScholeyAndrew B, KennedyDavid O

Cognitive enhancement

A soft drink containing caffeine and glucose, as well as flavouring levels of herbal extracts, resulted in significantly improved performance on 'secondary memory' and 'speed of attention' factors compared to placebo.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, Non-U.S. Gov'tResearch funding provided by government agencies outside the United States.

Language : English

45.

Cognitive and mood improvements of caffeine in habitual consumers and habitual non-consumers of caffeine.

Author: HaskellCrystal F, KennedyDavid O, WesnesKeith A, ScholeyAndrew B

Cognitive enhancement
Caffeine withdrawal

This study highlights the need for further research on the effects of caffeine in non-deprived, habitual caffeine users to separate the effects of caffeine from caffeine withdrawal.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

46.

Cognitive and psychomotor performance, mood, and pressor effects of caffeine after 4, 6 and 8 h caffeine abstinence.

Author: HeatherleySusan V, HaywardRobert C, SeersHelen E, RogersPeter J

Improve cognitive performance
Improve mood
Adverse effects
Increase blood pressure

Caffeine consumed after 8 hours of abstinence improves cognitive performance and mood, but has some adverse effects after shorter periods of abstinence.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, Non-U.S. Gov'tResearch funding provided by government agencies outside the United States.

Language : English

47.

Caffeine effects on recovery sleep following 27 h total sleep deprivation.

Author: LaJambeCynthia M, KamimoriGary H, BelenkyGregory, BalkinThomas J

Impaired sleep
Reduced sleep depth

Caffeine exerts mild deleterious dose-response effects on recovery sleep following total sleep deprivation, primarily early in the sleep period. Habitual caffeine use appears to minimally reduce caffeine effects.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

48.

Effects of caffeine on performance and mood: withdrawal reversal is the most plausible explanation.

Author: JamesJack E, RogersPeter J

Enhanced performance
Improved mood
Withdrawal effects

Caffeine is often believed to enhance performance and mood. This study examines the validity of this belief. It questions whether caffeine’s effects are due to net benefits or simply the reversal of withdrawal symptoms.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Meta-AnalysisA statistical technique that integrates the results of multiple studies to draw more general conclusions about a particular issue.

Language : English

49.

Effects of caffeine on the electrophysiological, cognitive and motor responses of the central nervous system.

Author: DeslandesA C, VeigaH, CagyM, PiedadeR, PompeuF, RibeiroP

Stimulatory effect

Caffeine is a stimulant that affects the brain. This study analyzed the effects of caffeine on electrophysiological, cognitive, and motor variables. The results suggest that caffeine has a stimulating effect on the central nervous system, but these effects may not be reflected in cognitive or motor performance.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, Non-U.S. Gov'tResearch funding provided by government agencies outside the United States.

Language : English

50.

Caffeine effects on resting-state arousal.

Author: BarryRobert J, RushbyJacqueline A, WallaceMark J, ClarkeAdam R, JohnstoneStuart J, ZlojutroIlinka

Increased arousal

Caffeine ingestion increased skin conductance level (SCL) and EEG alpha frequency, and decreased alpha power. These effects were used as markers of arousal increase.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

51.

Effects of repeated doses of caffeine on mood and performance of alert and fatigued volunteers.

Author: SmithAndrew, SutherlandDavid, ChristopherGary

Alertness improvement
Information encoding enhancement
Reaction time improvement

Caffeine led to a more positive mood and improved performance on a number of tasks.

Comparative StudyResearch that compares multiple groups/interventions to determine differences/similarities in outcomes/characteristics.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, Non-U.S. Gov'tResearch funding provided by government agencies outside the United States.

Language : English

52.

Psychostimulant and other effects of caffeine in 9- to 11-year-old children.

Author: HeatherleySusan V, HancockKatie M F, RogersPeter J

This study explores the effects of caffeine in children.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, Non-U.S. Gov'tResearch funding provided by government agencies outside the United States.

Language : English

53.

Laboratory and field studies of naps and caffeine as practical countermeasures for sleep-wake problems associated with night work.

Author: SchweitzerPaula K, RandazzoAngela C, StoneKara, ErmanMilton, WalshJames K

Improved alertness
Improved performance

Napping plus caffeine helps improve performance and alertness of night-shift workers.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, U.S. Gov't, P.H.S.Research funding provided by the Public Health Service (PHS).

Language : English

54.

Subjective, behavioral, and physiological effects of acute caffeine in light, nondependent caffeine users.

Author: ChildsEmma, de WitHarriet

Caffeine has mild stimulant effects but its effects are difficult to study in regular caffeine users due to tolerance and withdrawal. Some researchers believe that caffeine's stimulant effects are mostly due to withdrawal reversal, and that caffeine may not have direct effects on mood, alertness, or cognitive function in non-dependent individuals.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, N.I.H., ExtramuralResearch funding provided by the NIH to external research institutions and researchers.

Language : English

55.

Caffeine's influence on nicotine's effects in nonsmokers.

Author: BlankMelissa D, KleykampBethea A, JenningsJanine M, EissenbergThomas

Nicotine effects in non-smokers are not influenced by moderate caffeine doses.

Comparative StudyResearch that compares multiple groups/interventions to determine differences/similarities in outcomes/characteristics.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, N.I.H., ExtramuralResearch funding provided by the NIH to external research institutions and researchers.

Language : English

56.

Time for tea: mood, blood pressure and cognitive performance effects of caffeine and theanine administered alone and together.

Author: RogersPeter J, SmithJessica E, HeatherleySusan V, Pleydell-PearceC W

Blood pressure reduction
Cognitive performance
Relaxation

Theanine, present in tea but not coffee, may contribute to the perception of tea as less stimulating than coffee.

Comparative StudyResearch that compares multiple groups/interventions to determine differences/similarities in outcomes/characteristics.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, Non-U.S. Gov'tResearch funding provided by government agencies outside the United States.

Language : English

57.

The effects of L-theanine, caffeine and their combination on cognition and mood.

Author: HaskellCrystal F, KennedyDavid O, MilneAnthea L, WesnesKeith A, ScholeyAndrew B

Improved cognitive function
Reduced mental fatigue
Headache

L-theanine, an amino acid found in tea, when combined with caffeine, exhibited positive cognitive and mood effects, including improved reaction time, accuracy, and reduced mental fatigue.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

58.

Timing of caffeine's impact on autonomic and central nervous system measures: clarification of arousal effects.

Author: BarryRobert J, ClarkeAdam R, JohnstoneStuart J, RushbyJacqueline A

arousal modulation

This study examined the timing of caffeine effects on arousal levels using skin conductance level (SCL) as a marker. Caffeine was associated with increased SCL, increased respiratory rate, and a global reduction in alpha power.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, Non-U.S. Gov'tResearch funding provided by government agencies outside the United States.

Language : English

59.

Effects of oral administration of caffeine and D-ribose on mental fatigue.

Author: AtakaSuzuka, TanakaMasaaki, NozakiSatoshi, MizumaHiroshi, MizunoKei, TaharaTsuyoshi, SuginoTomohiro, ShiraiTomoko, KajimotoYoshitaka, KuratsuneHirohiko, KajimotoOsami, WatanabeYasuyoshi

Mental fatigue reduction
Task performance improvement
Deeper fatigue

Caffeine improved task performance in healthy volunteers by enhancing central nervous system activity without increasing the sensation of fatigue.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, Non-U.S. Gov'tResearch funding provided by government agencies outside the United States.

Language : English

60.

Enhanced mood and psychomotor performance by a caffeine-containing energy capsule in fatigued individuals.

Author: ChildsEmma, de WitHarriet

Cognitive enhancement

This study examined the effects of a caffeine-containing (200 mg) supplement on subjective effects and cognitive performance in fatigued individuals. Participants who consumed caffeine reported improved mood and reaction times compared to placebo.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, N.I.H., ExtramuralResearch funding provided by the NIH to external research institutions and researchers.

Language : English

61.

Effects of dietary caffeine on topographic EEG after controlling for withdrawal and withdrawal reversal.

Author: KeaneMichael A, JamesJack E, HoganMichael J

caffeine withdrawal
withdrawal reversal

Caffeine's effects on electroencephalogram (EEG) have been studied extensively, but consistent findings are lacking. This is likely due to differences in methodology and the failure to control for caffeine withdrawal and reversal effects.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

62.

Early effects of caffeinated and decaffeinated coffee on subjective state and gender differences.

Author: AdanAna, PratGemma, FabbriMarco, Sànchez-TuretMiquel

Subjective activation

This study examined the early effects of a single low dose of caffeine (100 mg) and decaffeinated coffee on sleepiness, subjective activation, and affect, considering the influence of gender and circadian typology. The study found that both caffeine and decaffeinated coffee produced early effects on subjective state, with potential differences based on gender and circadian typology. Further research is needed to explore these differences.

Controlled Clinical TrialA clinical trial that evaluates the effectiveness of a treatment by comparing a group that receives the intervention with a group that receives a placebo or standard treatment.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

63.

Caffeine improves physical and cognitive performance during exhaustive exercise.

Author: HogervorstEef, BandelowStephan, SchmittJeroen, JentjensRoy, OliveiraMarta, AllgroveJudith, CarterTom, GleesonMichael

Improved cognitive ability
Improved endurance performance

Caffeine in a performance bar can improve endurance performance and complex cognitive ability during and after exercise. Participants who consumed the caffeine bar had significantly faster reaction times and were able to sustain exercise for longer periods.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, Non-U.S. Gov'tResearch funding provided by government agencies outside the United States.

Language : English

64.

Effects of dietary caffeine on EEG, performance and mood when rested and sleep restricted.

Author: KeaneMichael A, JamesJack E

Ineffective for sleep loss

Caffeine had modest effects on EEG activity in the delta and beta bandwidths, but no overall effects on theta or alpha bandwidths. There was no evidence of caffeine's restorative effects on EEG, performance, or mood following sleep restriction.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

65.

Effects of caffeine in chewing gum on mood and attention.

Author: SmithAndrew

Alertness
Performance efficiency

This study explored the effects of caffeine gum on alertness and attention tasks. It found that even small doses of caffeine improved alertness and performance efficiency.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, Non-U.S. Gov'tResearch funding provided by government agencies outside the United States.

Language : English

66.

The effects of energy drinks alone and with alcohol on neuropsychological functioning.

Author: CurryKim, StasioMichael J

Neuropsychological effects

This study examines the neuropsychological effects of consuming a caffeinated energy drink combined with alcohol in young adults.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

67.

Caffeine expectancies influence the subjective and behavioral effects of caffeine.

Author: HarrellPaul T, JulianoLaura M

Improved performance

Manipulating the expected effects of caffeine altered the behavioral and subjective effects of caffeine. Caffeine improved reaction time and accuracy on the rapid visual information processing task.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

68.

Efficacy of acute caffeine ingestion for short-term high-intensity exercise performance: a systematic review.

Author: AstorinoTodd A, RobersonDaniel W

Exercise performance enhancement
Decreased performance

Caffeine, a stimulant, was found to improve performance in short-term high-intensity exercise, especially in elite athletes who do not regularly consume caffeine. The exact mechanism of caffeine's ergogenic effect is not fully understood.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
ReviewAn article that critically examines existing research on a particular topic and summarizes the current state of knowledge in the field.
Systematic ReviewA review that systematically collects, evaluates, and integrates relevant research to answer a specific research question.

Language : English

69.

Effects of caffeine and glucose, alone and combined, on cognitive performance.

Author: AdanAna, Serra-GrabulosaJosep Maria

Improved attention
Improved memory

Consuming both caffeine and glucose together was found to be more beneficial for cognitive performance than either substance alone. The combination improved sustained attention and verbal memory, while caffeine alone improved simple reaction time and glucose alone improved simple and sequential reaction time tasks and manual dexterity. Further research is needed to explore the mechanisms behind these synergistic effects.

Comparative StudyResearch that compares multiple groups/interventions to determine differences/similarities in outcomes/characteristics.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

70.

Habitual coffee and tea drinkers experienced increases in blood pressure after consuming low to moderate doses of caffeine; these increases were larger upright than in the supine posture.

Author: McMullenMichael K, WhitehouseJulie M, ShineGillian, TowellAnthony

Caffeine tolerance
Cardiovascular changes

Caffeine tolerance develops rapidly after regular caffeine consumption. However, this study found that habitual coffee and tea drinkers do not develop complete tolerance to lower doses of caffeine (67 and 133 mg). These doses led to increased systolic and diastolic blood pressure, aortic impedance, and decreased arterial compliance, particularly in an upright posture.

Comparative StudyResearch that compares multiple groups/interventions to determine differences/similarities in outcomes/characteristics.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

71.

Effects of caffeine on alcohol-related changes in behavioural control and perceived intoxication in light caffeine consumers.

Author: AttwoodAngela S, RogersPeter J, AtayaAlia F, AdamsSally, MunafòMarcus R

Alcohol related harms

The study investigated the combined effects of caffeine and alcohol on behavioral control and subjective measures in relation to caffeine consumer history.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, Non-U.S. Gov'tResearch funding provided by government agencies outside the United States.

Language : English

72.

Acute effects of caffeine on attention: a comparison of non-consumers and withdrawn consumers.

Author: SmithAndrew P, ChristopherGary, SutherlandDavid

Cognitive function

This study examined whether effects of caffeine could be explained in terms of reversal of the effects of caffeine withdrawal. The study found that ingestion of caffeine was associated with faster simple reaction time, fewer long responses, greater detection of targets in the cognitive vigilance task, and faster encoding of new information.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, Non-U.S. Gov'tResearch funding provided by government agencies outside the United States.

Language : English

73.

Effects of caffeine and alcohol on mood and performance changes following consumption of lager.

Author: SmithAndrew P

Counteracts alcohol-induced alertness drop
No effect on alcohol-induced performance

Caffeine does not remove the negative effects of alcohol on performance although high doses counteract the drop in subjective alertness produced by alcohol.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, Non-U.S. Gov'tResearch funding provided by government agencies outside the United States.

Language : English

74.

Effects of caffeine on vocal acoustic and aerodynamic measures of adult females.

Author: FrancaMaria Claudia, SimpsonKenneth Oliver, SchuetteAllison

A single 100mg dose of caffeine had no effect on vocal acoustics or aerodynamics, as evidenced by acoustic and aerodynamic measures.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

75.

Subjective and objective effects of coffee consumption - caffeine or expectations?

Author: DömötörZs, SzemerszkyR, KötelesF

Placebo effect

This study investigated the impact of 5 mg/kg caffeine, chance of receiving caffeine (stimulus expectancies), and expectations of effects of caffeine (response expectancies) on objective and subjective variables. Consumption of 5 mg/kg caffeine had an impact on participants' SBP, standard deviation of normal heartbeat intervals, HR (decrease), and subjective experience 40 minutes later even after controlling for respective baseline values, stimulus and response expectancies, and habitual caffeine consumption.

Comparative StudyResearch that compares multiple groups/interventions to determine differences/similarities in outcomes/characteristics.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, Non-U.S. Gov'tResearch funding provided by government agencies outside the United States.

Language : English

76.

Caffeine: cognitive and physical performance enhancer or psychoactive drug?

Author: CappellettiSimone, PiacentinoDaria, DariaPiacentino, SaniGabriele, AromatarioMariarosaria

Concentration enhancement
Memory enhancement
Physical performance improvement
Caffeine dependence
Caffeine intoxication

Caffeine use is increasing, and while it can enhance alertness and physical performance, excessive intake can lead to negative effects on the heart and nervous system.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Meta-AnalysisA statistical technique that integrates the results of multiple studies to draw more general conclusions about a particular issue.
Research Support, Non-U.S. Gov'tResearch funding provided by government agencies outside the United States.
ReviewAn article that critically examines existing research on a particular topic and summarizes the current state of knowledge in the field.

Language : English

77.

Acute personalized habitual caffeine doses improve attention and have selective effects when considering the fractionation of executive functions.

Author: LaniniJuliana, GaldurózJosé Carlos Fernandes, PompéiaSabine

Improved attention
Improved executive updating
Reduced fatigue

Caffeine improved simple and sustained attention and executive updating in healthy males, regardless of whether it was consumed with food. This effect was not influenced by the habitual weekly dose of caffeine or by changes in mood, meal ingestion, or cognitive effort.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, Non-U.S. Gov'tResearch funding provided by government agencies outside the United States.

Language : English

78.

Separate and joint effects of alcohol and caffeine on conflict monitoring and adaptation.

Author: BaileyKira, AmlungMichael T, MorrisDavid H, PriceMason H, Von GuntenCurtis, McCarthyDenis M, BartholowBruce D

Conflict monitoring
Cognitive impairment

Caffeine leads to exaggeration of attentional resource utilization, which could provide short-term benefits but lead to problems conserving resources for when they are most needed. Alcohol did not abolish conflict monitoring or adaptation. Caffeine eliminated conflict adaptation in sequential trials but also enhanced neural conflict monitoring.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, N.I.H., ExtramuralResearch funding provided by the NIH to external research institutions and researchers.

Language : English

79.

Placebo effects of caffeine on maximal voluntary concentric force of the knee flexors and extensors.

Author: TallisJason, MuhammadBilal, IslamMohammed, DuncanMichael J

Muscle strength
Expectancy
Motivation

Caffeine caused an improvement in some aspects of muscle strength, but there was no additional effect of expectancy. Performance was poorer in participants who believed caffeine would have the greatest benefit, which highlights a link between expected ergogenicity, motivation, and personality characteristics.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, Non-U.S. Gov'tResearch funding provided by government agencies outside the United States.

Language : English

80.

Acute effects of theanine, caffeine and theanine-caffeine combination on attention.

Author: KahathuduwaChanaka N, DassanayakeTharaka L, AmarakoonA M Tissa, WeerasingheVajira S

Cognitive function enhancement

Theanine, a constituent of tea, may have acute positive effects on cognitive function, particularly attention, when combined with caffeine.

Clinical TrialA clinical trial is a planned study conducted on humans to evaluate the efficacy and safety of pharmaceuticals, medical devices, and treatment methods. It aims to explore the possibilities of new treatments and improve the health of patients.
Comparative StudyResearch that compares multiple groups/interventions to determine differences/similarities in outcomes/characteristics.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

81.

Coffee, caffeine, and sleep: A systematic review of epidemiological studies and randomized controlled trials.

Author: ClarkIan, LandoltHans Peter

Improved performance
Treatment for apnea
Sleep disruption

This review examined the effects of caffeine on sleep. Caffeine typically prolonged sleep latency, reduced sleep time and efficiency, and worsened sleep quality.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
ReviewAn article that critically examines existing research on a particular topic and summarizes the current state of knowledge in the field.
Systematic ReviewA review that systematically collects, evaluates, and integrates relevant research to answer a specific research question.

Language : English

82.

Simultaneous coffee caffeine intake and sleep deprivation alter glucose homeostasis in Iranian men: a randomized crossover trial.

Author: RasaeiBehrouz, TalibRuzita Abd, NoorMohd Ismail, KarandishMajid, KarimNorimah A

Increased insulin

Caffeinated coffee, when consumed during sleep deprivation, was more detrimental to glucose homeostasis compared to decaffeinated coffee. This resulted in higher serum glucose and insulin levels after an oral glucose tolerance test, higher fasting serum insulin, and increased insulin resistance.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

83.

Systematic review of the potential adverse effects of caffeine consumption in healthy adults, pregnant women, adolescents, and children.

Author: WikoffDaniele, WelshBrian T, HendersonRayetta, BrorbyGregory P, BrittJanice, MyersEsther, GoldbergerJeffrey, LiebermanHarris R, O'BrienCharles, PeckJennifer, TenenbeinMilton, WeaverConnie, HarveySeneca, UrbanJonathan, DoepkerCandace

Acute effects
Behavioral effects
Bone status
Cardiovascular toxicity
Reproductive and developmental effects

This systematic review updated a previous assessment of caffeine safety, evaluating data published from 2001 to 2015. The review found that consumption of up to 400 mg caffeine/day in healthy adults and 300 mg caffeine/day in healthy pregnant women is generally not associated with adverse health effects. Further research is needed to characterize effects in sensitive populations and establish better quantitative characterization of interindividual variability.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
ReviewAn article that critically examines existing research on a particular topic and summarizes the current state of knowledge in the field.
Systematic ReviewA review that systematically collects, evaluates, and integrates relevant research to answer a specific research question.

Language : English

84.

Does the placebo effect modulate drug bioavailability? Randomized cross-over studies of three drugs.

Author: HammamiMuhammad M, YusufAhmed, ShireFaduma S, HusseinRajaa, Al-SwayehReem

This study was designed to evaluate the concept that awareness of drug ingestion may modulate drug bioavailability, using different drugs.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

85.

Caffeine, CYP1A2 Genotype, and Endurance Performance in Athletes.

Author: GuestNanci, CoreyPaul, VescoviJason, El-SohemyAhmed

Exercise performance enhancement

This study investigated whether variation in the CYP1A2 gene, which affects caffeine metabolism, modifies the ergogenic effects of caffeine in a 10-km cycling time trial. The study found no significant effect of CYP1A2 genotype on caffeine's ergogenic effect.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Multicenter StudyResearch conducted in collaboration with multiple research institutions. It aims to collect a wide range of data and obtain more generalizable results.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.
Research Support, Non-U.S. Gov'tResearch funding provided by government agencies outside the United States.

Language : English

86.

The Acute Effects of Caffeinated Black Coffee on Cognition and Mood in Healthy Young and Older Adults.

Author: Haskell-RamsayCrystal F, JacksonPhilippa A, ForsterJoanne S, DoddFiona L, BowerbankSamantha L, KennedyDavid O

Improved cognition
Improved mood
Jittery ratings

This study compared the effects of regular coffee, decaffeinated coffee, and placebo on measures of cognition and mood. The study found that regular coffee produced the expected effects of decreased reaction time and increased alertness when compared to placebo.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

87.

Challenging the Myth of Non-Response to the Ergogenic Effects of Caffeine Ingestion on Exercise Performance.

Author: Del CosoJuan, LaraBeatriz, Ruiz-MorenoCarlos, SalineroJuan José

Improved athletic performance
Slight decrease in performance

Caffeine is known to improve exercise performance, but some individuals may show minimal or no ergogenic effect. This study demonstrates that even "non-responders" to caffeine showed a significant ergogenic effect when performance was measured repeatedly under controlled conditions.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

88.

Effects of caffeine on neuromuscular function in a non-fatigued state and during fatiguing exercise.

Author: MesquitaRicardo N O, CroninNeil J, KyröläinenHeikki, HintikkaJukka, AvelaJanne

Exercise performance

This study examines the effects of caffeine on neuromuscular function in a non-fatigued state and during fatiguing exercise. The findings indicate that caffeine can decrease inhibitory mechanisms in the central nervous system, leading to improved exercise performance and accelerated recovery.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

89.

Expectation for stimulant type modifies caffeine's effects on mood and cognition among college students.

Author: LoobyAlison, ZimmermanLauren, LivingstonNicholas R

Cognitive enhancement
Mood enhancement

College students who expect to receive a strong stimulant, such as Adderall, report stronger amphetamine effects and perform better on a working memory test, even when they receive caffeine. This suggests that expectancies can modify the effects of caffeine.

Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.
Randomized Controlled TrialA clinical trial that randomly assigns participants to treatment and control groups to evaluate the effects of an intervention.

Language : English

90.

Genetics of caffeine and brain-related outcomes - a systematic review of observational studies and randomized trials.

Author: KapellouAngeliki, KingAlexandra, GrahamCatherine A M, PilicLeta, MavrommatisYiannis

Anxiogenic effects
Stimulant effects

Caffeine is a stimulant that can cause anxiety. Research on the specific effects of caffeine on the brain is controversial. This review discusses the evidence suggesting that interindividual differences in caffeine response may be partly due to variations in genes such as CYP1A2 and ADORA2A.

Systematic ReviewA review that systematically collects, evaluates, and integrates relevant research to answer a specific research question.
Journal ArticleAn article published in an academic or professional journal that reports original research or scholarly analysis.

Language : English

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