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Abdolmaleki M, Ohadi L, Changizi F, Seyed S, Farjam M. The risk of premature cardiac contractions (PAC/PVC) related to caffeine consumption among healthcare workers: A comprehensive review. Health Sci Rep 2024; 7:e2222. [PMID: 39006153 PMCID: PMC11239532 DOI: 10.1002/hsr2.2222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 06/10/2024] [Accepted: 06/17/2024] [Indexed: 07/16/2024] Open
Abstract
Background and Aims Premature atrial contractions (PACs) and premature ventricular contractions (PVCs) are ectopic heart rhythm disorders with implications for cardiovascular health. This study explores the relationship between caffeine consumption and the risk of PACs and PVCs, with a focus on healthcare workers, such as doctors, nurses, pharmacists, and midwives, who often rely on caffeine to combat fatigue, especially during night shifts. Methods A thorough review was conducted through PubMed, Scopus, Google Scholar, and Web of Science, utilizing a combination of MeSH terms and keywords. Studies examining the link between caffeine consumption and PACs and PVCs, particularly in healthcare workers, were included. Results We found that caffeine shows various effects based on dosage and can impact arrhythmia risk. Individuals working long shifts, including healthcare professionals, are prone to increased caffeine intake, leading to higher cardiovascular risk. To mitigate these risks, tailored guidelines for caffeine consumption, flexible shift scheduling, and mental health support services are recommended. Promoting caffeine alternatives within healthcare institutions can be beneficial. Conclusion Although caffeine may have potential benefits, its drawbacks, particularly concerning cardiovascular health, may surpass its advantages, especially when consumed in high doses. A multidisciplinary approach is crucial for healthcare workers' well-being and quality of patient care. Further research is required to refine and support these recommendations.
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Affiliation(s)
- Maryam Abdolmaleki
- Department of Medicine, School of Medicine Shahid Beheshti University of Medical Sciences Tehran Iran
| | - Laya Ohadi
- Department of Medicine, School of Medicine Shahid Beheshti University of Medical Sciences Tehran Iran
| | - Faraz Changizi
- Department of Medicine, School of Medicine Shahid Beheshti University of Medical Sciences Tehran Iran
| | - Sara Seyed
- Department of Medicine, School of Medicine Semnan University of Medical Sciences Tehran Iran
| | - Mina Farjam
- Department of Medicine, School of Medicine Shahid Beheshti University of Medical Sciences Tehran Iran
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Song X, Kirtipal N, Lee S, Malý P, Bharadwaj S. Current therapeutic targets and multifaceted physiological impacts of caffeine. Phytother Res 2023; 37:5558-5598. [PMID: 37679309 DOI: 10.1002/ptr.8000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 08/04/2023] [Accepted: 08/17/2023] [Indexed: 09/09/2023]
Abstract
Caffeine, which shares consubstantial structural similarity with purine adenosine, has been demonstrated as a nonselective adenosine receptor antagonist for eliciting most of the biological functions at physiologically relevant dosages. Accumulating evidence supports caffeine's beneficial effects against different disorders, such as total cardiovascular diseases and type 2 diabetes. Conversely, paradoxical effects are also linked to caffeine ingestion in humans including hypertension-hypotension and tachycardia-bradycardia. These observations suggest the association of caffeine action with its ingested concentration and/or concurrent interaction with preferential molecular targets to direct explicit events in the human body. Thus, a coherent analysis of the functional targets of caffeine, relevant to normal physiology, and disease pathophysiology, is required to understand the pharmacology of caffeine. This review provides a broad overview of the experimentally validated targets of caffeine, particularly those of therapeutic interest, and the impacts of caffeine on organ-specific physiology and pathophysiology. Overall, the available empirical and epidemiological evidence supports the dose-dependent functional activities of caffeine and advocates for further studies to get insights into the caffeine-induced changes under specific conditions, such as asthma, DNA repair, and cancer, in view of its therapeutic applications.
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Affiliation(s)
- Xinjie Song
- Zhejiang Provincial Key Lab for Chemical and Biological Processing Technology of Farm Product, School of Biological and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou, China
| | - Nikhil Kirtipal
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju, Republic of Korea
| | - Sunjae Lee
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju, Republic of Korea
| | - Petr Malý
- Laboratory of Ligand Engineering, Institute of Biotechnology of the Czech Academy of Sciences v.v.i, BIOCEV Research Center, Vestec, Czech Republic
| | - Shiv Bharadwaj
- Laboratory of Ligand Engineering, Institute of Biotechnology of the Czech Academy of Sciences v.v.i, BIOCEV Research Center, Vestec, Czech Republic
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Kapellou A, King A, Graham CAM, Pilic L, Mavrommatis Y. Genetics of caffeine and brain-related outcomes - a systematic review of observational studies and randomized trials. Nutr Rev 2023; 81:1571-1598. [PMID: 37029915 DOI: 10.1093/nutrit/nuad029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/09/2023] Open
Abstract
CONTEXT Although the stimulant and anxiogenic properties of caffeine are widely accepted, research on its specific effects on the brain remains controversial. Growing evidence shows that interindividual differences in caffeine response may be partly due to variations in genes such as CYP1A2 and ADORA2A, which have been used to identify individuals as "fast" or "slow" caffeine metabolizers and as having a "high" or "low" caffeine sensitivity, respectively. OBJECTIVE The objective of this review was to identify, evaluate, and discuss current evidence on the associations between common genetic variants, caffeine consumption, and brain-related outcomes in humans. DATA SOURCES PubMed and Embase databases were searched for relevant reports based on a predetermined search strategy. DATA EXTRACTION Reports of observational and experimental studies on healthy adults who underwent (a) genetic analysis for polymorphisms in genes associated with caffeine metabolism and effects and (b) measurements of brain-related effects such as anxiety, insomnia, and cognitive performance associated with the consumption of caffeine (habitual intake or supplementation) were included. DATA ANALYSIS Of the 22 records included, 15 were randomized controlled trials, 6 were cross-sectional studies, and 1 was a genome-wide association study. The main outcomes identified were cognitive performance (n = 9), anxiety (n = 7), and sleep disturbance/insomnia (n = 6). Polymorphisms in the CYP1A2 gene were associated with cognitive function, while variations in the ADORA2A gene were associated with anxiety and sleep disturbance. CONCLUSION The present review has provided evidence that variability in the CYP1A2 and the ADORA2A genes may modulate the association between caffeine and brain-related outcomes. Future studies are warranted to investigate the specific polymorphisms implicated in each brain outcome, which cognitive functions are particularly related to caffeine (simple vs complex), whether there are gender differences in anxiety effects, and how habitual caffeine intake may influence the acute effects of caffeine. SYSTEMATIC REVIEW REGISTRATION PROSPERO registration no. CRD42021257556.
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Affiliation(s)
- Angeliki Kapellou
- Faculty of Sport, Allied Health and Performance Science (SAHPS), St Mary's University, Twickenham, United Kingdom
| | - Alexandra King
- Faculty of Sport, Allied Health and Performance Science (SAHPS), St Mary's University, Twickenham, United Kingdom
| | - Catherine A M Graham
- Center for Interdisciplinary Research (CEFIR), Cereneo Foundation, Vitznau, Switzerland
| | - Leta Pilic
- Faculty of Sport, Allied Health and Performance Science (SAHPS), St Mary's University, Twickenham, United Kingdom
| | - Yiannis Mavrommatis
- Faculty of Sport, Allied Health and Performance Science (SAHPS), St Mary's University, Twickenham, United Kingdom
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4
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Becker M, Repantis D, Dresler M, Kühn S. Cognitive enhancement: Effects of methylphenidate, modafinil, and caffeine on latent memory and resting state functional connectivity in healthy adults. Hum Brain Mapp 2022; 43:4225-4238. [PMID: 35670369 PMCID: PMC9435011 DOI: 10.1002/hbm.25949] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 04/15/2022] [Accepted: 04/20/2022] [Indexed: 12/02/2022] Open
Abstract
Stimulants like methylphenidate, modafinil, and caffeine have repeatedly shown to enhance cognitive processes such as attention and memory. However, brain-functional mechanisms underlying such cognitive enhancing effects of stimulants are still poorly characterized. Here, we utilized behavioral and resting-state fMRI data from a double-blind randomized placebocontrolled study of methylphenidate, modafinil, and caffeine in 48 healthy male adults. The results show that performance in different memory tasks is enhanced, and functional connectivity (FC) specifically between the frontoparietal network (FPN) and default mode network (DMN) is modulated by the stimulants in comparison to placebo. Decreased negative connectivity between right prefrontal and medial parietal but also between medial temporal lobe and visual brain regions predicted stimulant-induced latent memory enhancement. We discuss dopamine's role in attention and memory as well as its ability to modulate FC between large-scale neural networks (e.g., FPN and DMN) as a potential cognitive enhancement mechanism.
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Affiliation(s)
- Maxi Becker
- Department of PsychologyHumboldt‐University BerlinBerlinGermany
- Department of Psychiatry and PsychotherapyUniversity Medical Center Hamburg‐EppendorfHamburgGermany
| | - Dimitris Repantis
- Department of Psychiatry and PsychotherapyCharité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt‐Universität zu BerlinBerlinGermany
| | - Martin Dresler
- Donders Institute for Brain, Cognition and BehaviourRadboud University Medical Center NijmegenNijmegenThe Netherlands
| | - Simone Kühn
- Department of Psychiatry and PsychotherapyUniversity Medical Center Hamburg‐EppendorfHamburgGermany
- Lise Meitner Group for Environmental NeuroscienceMax Planck Institute for Human DevelopmentBerlinGermany
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5
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Reichert CF, Deboer T, Landolt HP. Adenosine, caffeine, and sleep-wake regulation: state of the science and perspectives. J Sleep Res 2022; 31:e13597. [PMID: 35575450 PMCID: PMC9541543 DOI: 10.1111/jsr.13597] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 03/18/2022] [Indexed: 01/11/2023]
Abstract
For hundreds of years, mankind has been influencing its sleep and waking state through the adenosinergic system. For ~100 years now, systematic research has been performed, first started by testing the effects of different dosages of caffeine on sleep and waking behaviour. About 70 years ago, adenosine itself entered the picture as a possible ligand of the receptors where caffeine hooks on as an antagonist to reduce sleepiness. Since the scientific demonstration that this is indeed the case, progress has been fast. Today, adenosine is widely accepted as an endogenous sleep‐regulatory substance. In this review, we discuss the current state of the science in model organisms and humans on the working mechanisms of adenosine and caffeine on sleep. We critically investigate the evidence for a direct involvement in sleep homeostatic mechanisms and whether the effects of caffeine on sleep differ between acute intake and chronic consumption. In addition, we review the more recent evidence that adenosine levels may also influence the functioning of the circadian clock and address the question of whether sleep homeostasis and the circadian clock may interact through adenosinergic signalling. In the final section, we discuss the perspectives of possible clinical applications of the accumulated knowledge over the last century that may improve sleep‐related disorders. We conclude our review by highlighting some open questions that need to be answered, to better understand how adenosine and caffeine exactly regulate and influence sleep.
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Affiliation(s)
- Carolin Franziska Reichert
- Centre for Chronobiology, University Psychiatric Clinics Basel, Basel, Switzerland.,Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Basel, Switzerland.,Center for Affective, Stress, and Sleep Disorders, University Psychiatric Clinics Basel, Basel, Switzerland
| | - Tom Deboer
- Laboratory for Neurophysiology, Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, the Netherlands
| | - Hans-Peter Landolt
- Institute of Pharmacology and Toxicology, University of Zürich, Zürich, Switzerland.,Sleep & Health Zürich, University Center of Competence, University of Zürich, Zürich, Switzerland
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6
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Guest NS, VanDusseldorp TA, Nelson MT, Grgic J, Schoenfeld BJ, Jenkins NDM, Arent SM, Antonio J, Stout JR, Trexler ET, Smith-Ryan AE, Goldstein ER, Kalman DS, Campbell BI. International society of sports nutrition position stand: caffeine and exercise performance. J Int Soc Sports Nutr 2021; 18:1. [PMID: 33388079 PMCID: PMC7777221 DOI: 10.1186/s12970-020-00383-4] [Citation(s) in RCA: 193] [Impact Index Per Article: 64.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 10/31/2020] [Indexed: 12/13/2022] Open
Abstract
Following critical evaluation of the available literature to date, The International Society of Sports Nutrition (ISSN) position regarding caffeine intake is as follows: 1. Supplementation with caffeine has been shown to acutely enhance various aspects of exercise performance in many but not all studies. Small to moderate benefits of caffeine use include, but are not limited to: muscular endurance, movement velocity and muscular strength, sprinting, jumping, and throwing performance, as well as a wide range of aerobic and anaerobic sport-specific actions. 2. Aerobic endurance appears to be the form of exercise with the most consistent moderate-to-large benefits from caffeine use, although the magnitude of its effects differs between individuals. 3. Caffeine has consistently been shown to improve exercise performance when consumed in doses of 3-6 mg/kg body mass. Minimal effective doses of caffeine currently remain unclear but they may be as low as 2 mg/kg body mass. Very high doses of caffeine (e.g. 9 mg/kg) are associated with a high incidence of side-effects and do not seem to be required to elicit an ergogenic effect. 4. The most commonly used timing of caffeine supplementation is 60 min pre-exercise. Optimal timing of caffeine ingestion likely depends on the source of caffeine. For example, as compared to caffeine capsules, caffeine chewing gums may require a shorter waiting time from consumption to the start of the exercise session. 5. Caffeine appears to improve physical performance in both trained and untrained individuals. 6. Inter-individual differences in sport and exercise performance as well as adverse effects on sleep or feelings of anxiety following caffeine ingestion may be attributed to genetic variation associated with caffeine metabolism, and physical and psychological response. Other factors such as habitual caffeine intake also may play a role in between-individual response variation. 7. Caffeine has been shown to be ergogenic for cognitive function, including attention and vigilance, in most individuals. 8. Caffeine may improve cognitive and physical performance in some individuals under conditions of sleep deprivation. 9. The use of caffeine in conjunction with endurance exercise in the heat and at altitude is well supported when dosages range from 3 to 6 mg/kg and 4-6 mg/kg, respectively. 10. Alternative sources of caffeine such as caffeinated chewing gum, mouth rinses, energy gels and chews have been shown to improve performance, primarily in aerobic exercise. 11. Energy drinks and pre-workout supplements containing caffeine have been demonstrated to enhance both anaerobic and aerobic performance.
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Affiliation(s)
- Nanci S Guest
- Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, 1 King's College Circle, Room 5326A, Toronto, ON, M5S 1A8, Canada.
| | - Trisha A VanDusseldorp
- Department of Exercise Science and Sport Management, Kennesaw State University, Kennesaw, GA, 30144, USA
| | | | - Jozo Grgic
- Institute for Health and Sport (IHES), Victoria University, Melbourne, Australia
| | - Brad J Schoenfeld
- Department of Health Sciences, CUNY Lehman College, Bronx, NY, 10468, USA
| | - Nathaniel D M Jenkins
- Department of Health and Human Physiology, University of Iowa, Iowa City, IA, 52240, USA
| | - Shawn M Arent
- Department of Exercise Science, Arnold School of Public Health, University of South Carolina, Colombia, SC, 29208, USA
- School of Social and Health Sciences, Leeds Trinity University, Leeds, UK
| | - Jose Antonio
- Exercise and Sport Science, Nova Southeastern University, Davie, FL, 33314, USA
| | - Jeffrey R Stout
- Institue of Exercise Physiology and Rehabilitation Science, University of Central Florida, Orlando, FL, 32816, USA
| | | | - Abbie E Smith-Ryan
- Department of Exercise and Sport Science, Applied Physiology Laboratory, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Erica R Goldstein
- Institue of Exercise Physiology and Rehabilitation Science, University of Central Florida, Orlando, FL, 32816, USA
| | - Douglas S Kalman
- Nutrion Department, College of Osteopathic Medicine, Nova Southeastern University, Fort Lauderdale, FL, 33314, USA
- Scientific Affairs. Nutrasource, Guelph, ON, Canada
| | - Bill I Campbell
- Performance & Physique Enhancement Laboratory, University of South Florida, Tampa, FL, 33612, USA
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7
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Abstract
Mnemonic discrimination is the ability to discriminate among similar memories, which requires separable representations of similar information. The neurocomputational process that assumedly decorrelates representations during encoding and consolidation is referred to as pattern separation. Deficits in pattern separation contribute to age-related declines in mnemonic functioning, which has motivated the development of targeted interventions. We followed-up a recent report that one 200 mg-dose of caffeine administered post-study enhances mnemonic discrimination [Borota, D., Murray, E., Keceli, G., Chang, A., Watabe, J. M., Ly, M., Toscano, J. P., & Yassa, M. A. (2014). Post-study caffeine administration enhances memory consolidation in humans. Nature Neuroscience, 17(2), 201-203. https://doi.org/10.1038/nn.3623]. To test whether the reported enhancements are an artifact of performance-impairing withdrawal symptoms in the control group, we did not restrict preexperimental caffeine intake and statistically adjusted treatment effects for habitual caffeine consumption. We detected no effects of caffeine and nonsuperiority testing ruled out medium and large enhancements in both average (1200 mg per week) and low-consumers (50 mg per week). Our results raise doubts about a caffeine-mediated enhancement of mnemonic discrimination on two counts: If the effect exists, it (1) is substantially smaller than originally reported and (2) may reflect an offset of performance-impairing withdrawal symptoms rather than genuinely enhanced consolidation. We recommend that future studies employ an alternating exposure-abstinence protocol, use an active control group, and verify posttreatment caffeine abstinence via saliva or blood samples.
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Affiliation(s)
- Frederik Aust
- Department Psychology, University of Cologne, Cologne, Germany
| | - Christoph Stahl
- Department Psychology, University of Cologne, Cologne, Germany
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8
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Weibel J, Lin YS, Landolt HP, Garbazza C, Kolodyazhniy V, Kistler J, Rehm S, Rentsch K, Borgwardt S, Cajochen C, Reichert CF. Caffeine-dependent changes of sleep-wake regulation: Evidence for adaptation after repeated intake. Prog Neuropsychopharmacol Biol Psychiatry 2020; 99:109851. [PMID: 31866308 DOI: 10.1016/j.pnpbp.2019.109851] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 12/10/2019] [Accepted: 12/12/2019] [Indexed: 10/25/2022]
Abstract
BACKGROUND Circadian and sleep-homeostatic mechanisms regulate timing and quality of wakefulness. To enhance wakefulness, daily consumption of caffeine in the morning and afternoon is highly common. However, the effects of such a regular intake pattern on circadian sleep-wake regulation are unknown. Thus, we investigated if daily daytime caffeine intake and caffeine withdrawal affect circadian rhythms and wake-promotion in habitual consumers. METHODS Twenty male young volunteers participated in a randomised, double-blind, within-subject study with three conditions: i) caffeine (150 mg 3 x daily for 10 days), ii) placebo (3 x daily for 10 days) and iii) withdrawal (150 mg caffeine 3 x daily for eight days, followed by a switch to placebo for two days). Starting on day nine of treatment, salivary melatonin and cortisol, evening nap sleep as well as sleepiness and vigilance performance throughout day and night were quantified during 43 h in an in-laboratory, light and posture-controlled protocol. RESULTS Neither the time course of melatonin (i.e. onset, amplitude or area under the curve) nor the time course of cortisol was significantly affected by caffeine or withdrawal. During withdrawal, however, volunteers reported increased sleepiness, showed more attentional lapses as well as polysomnography-derived markers of elevated sleep propensity in the late evening compared to both the placebo and caffeine condition. CONCLUSIONS The typical pattern of caffeine intake with consumption in both the morning and afternoon hours may not necessarily result in a circadian phase shift in the evening nor lead to clear-cut benefits in alertness. The time-of-day independent effects of caffeine withdrawal on evening nap sleep, sleepiness and performance suggest an adaptation to the substance, presumably in the homeostatic aspect of sleep-wake regulation.
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Affiliation(s)
- Janine Weibel
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Basel, Switzerland; Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Basel, Switzerland
| | - Yu-Shiuan Lin
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Basel, Switzerland; Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Basel, Switzerland; Neuropsychiatry and Brain Imaging, Psychiatric Hospital of the University of Basel, Basel, Switzerland
| | - Hans-Peter Landolt
- Institute of Pharmacology and Toxicology, University of Zürich, Zürich, Switzerland; Sleep & Health Zürich, University Center of Competence, University of Zürich, Zürich, Switzerland
| | - Corrado Garbazza
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Basel, Switzerland; Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Basel, Switzerland
| | | | - Joshua Kistler
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Basel, Switzerland; Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Basel, Switzerland
| | - Sophia Rehm
- Laboratory Medicine, University Hospital Basel, Basel, Switzerland
| | | | - Stefan Borgwardt
- Neuropsychiatry and Brain Imaging, Psychiatric Hospital of the University of Basel, Basel, Switzerland
| | - Christian Cajochen
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Basel, Switzerland; Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Basel, Switzerland.
| | - Carolin Franziska Reichert
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Basel, Switzerland; Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Basel, Switzerland
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9
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Areta JL, Irwin C, Desbrow B. Inaccuracies in caffeine intake quantification and other important limitations in recent publication by Gonçalves et al. J Appl Physiol (1985) 2019; 123:1414. [PMID: 29167205 DOI: 10.1152/japplphysiol.00489.2017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 06/16/2017] [Accepted: 06/21/2017] [Indexed: 11/22/2022] Open
Affiliation(s)
- J L Areta
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway; and
| | - C Irwin
- Menzies Health Institute Queensland and School of Allied Health Sciences, Griffith University, Gold Coast, Australia
| | - B Desbrow
- Menzies Health Institute Queensland and School of Allied Health Sciences, Griffith University, Gold Coast, Australia
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10
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Aidman E, Johnson K, Hoggan BL, Fidock J, Paech GM, Della Vedova CB, Pajcin M, Grant C, Kamimori G, Mitchelson E, Banks S. Synchronized drowsiness monitoring and simulated driving performance data under 50-hr sleep deprivation: A double-blind placebo-controlled caffeine intervention. Data Brief 2018; 19:1335-1340. [PMID: 30229009 PMCID: PMC6141128 DOI: 10.1016/j.dib.2018.06.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 05/23/2018] [Accepted: 06/05/2018] [Indexed: 12/02/2022] Open
Abstract
This paper presents the 60-s time-resolution segment from our 50-h total sleep deprivation (TSD) dataset (Aidman et al., 2018) [1] that captures minute-by-minute dynamics of driving performance (lane keeping and speed variability) along with objective, oculography-derived drowsiness estimates synchronised to the same 1-min driving epochs. Eleven participants (5 females, aged 18–28) were randomised into caffeine (administered in four 200 mg doses via chewing gum in the early morning hours) or placebo groups. Every three hours they performed a 40 min simulated drive in a medium fidelity driving simulator, while their drowsiness was continuously measured with a spectacle frame-mounted infra-red alertness monitoring system. The dataset covers 15 driving periods of 40 min each, and thus contains over 600 data points of paired data per participant. The 1-min time resolution enables detailed time-series analyses of both time-since-wake and time-on-task performance dynamics and associated drowsiness levels. It also enables direct examination of the relationships between drowsiness and task performance measures. The question of how these relationships might change under various intervention conditions (caffeine in our case) seems worth further investigation.
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Affiliation(s)
- E Aidman
- Defence Science and Technology Group, Land Division, Edinburgh, Australia
| | - K Johnson
- Defence Science and Technology Group, Land Division, Edinburgh, Australia
| | - B L Hoggan
- Defence Science and Technology Group, Land Division, Edinburgh, Australia
| | - J Fidock
- Defence Science and Technology Group, Land Division, Edinburgh, Australia
| | - G M Paech
- University of South Australia, School of Psychology, Social Work and Social Policy, Centre for Sleep Research, Adelaide, Australia
| | - C B Della Vedova
- University of South Australia, School of Pharmacy and Medical Sciences, Adelaide, Australia
| | - M Pajcin
- University of South Australia, School of Pharmacy and Medical Sciences, Adelaide, Australia
| | - C Grant
- University of South Australia, School of Psychology, Social Work and Social Policy, Centre for Sleep Research, Adelaide, Australia
| | - G Kamimori
- Behavioral Biology Branch, Center for Military Psychiatry and Neuroscience Research, Walter Reed Army Institute of Research, Silver Spring, United States
| | - E Mitchelson
- Defence Science and Technology Group, Land Division, Edinburgh, Australia
| | - S Banks
- University of South Australia, School of Psychology, Social Work and Social Policy, Centre for Sleep Research, Adelaide, Australia
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11
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James JE. Are coffee's alleged health protective effects real or artifact? The enduring disjunction between relevant experimental and observational evidence. J Psychopharmacol 2018; 32:850-854. [PMID: 29737228 DOI: 10.1177/0269881118771780] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND There is a large corpus of observational evidence claiming that coffee is health protective and a similarly large corpus of experimental psychopharmacological evidence to suggest that habitual caffeine consumption may be harmful to health. AIM The purpose of this study was to examine the disjunction between observational and experimental findings with specific reference to the implications of coffee/caffeine consumption for elevated blood pressure, cardiovascular disease, type 2 diabetes and neurodegenerative disease. METHOD Illustrative recent major reviews alleging health protective effects from coffee consumption were examined in light of findings from relevant experimental studies of caffeine. FINDINGS Decades-long coffee consumption is but one of countless lifestyle variables that may benefit or harm health. Contradictions concerning the implications of coffee/caffeine consumption for health between observational and experimental research are attributable mostly to poor control over potential confounders in observational studies. CONCLUSION When considered in the context of experimental evidence concerning caffeine's known pharmacological actions, there is reason to be sceptical about observational findings alleging health-protective effects from coffee consumption. Long-term randomised trials are needed to end the enduring interpretative disjunction between observational and experimental evidence concerning coffee/caffeine consumption and health.
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12
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Dietz C, Dekker M. Effect of Green Tea Phytochemicals on Mood and Cognition. Curr Pharm Des 2018; 23:2876-2905. [PMID: 28056735 DOI: 10.2174/1381612823666170105151800] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 01/01/2017] [Indexed: 11/22/2022]
Abstract
BACKGROUND Green tea is traditionally known to induce mental clarity, cognitive function, physical activation and relaxation. Recently, a special green tea, matcha tea, is rapidly gaining popularity throughout the world and is frequently referred to as a mood- and brain food. Matcha tea consumption leads to much higher intake of green tea phytochemicals compared to regular green tea. Previous research on tea constituents caffeine, L-theanine, and epigallocatechin gallate (EGCG) repeatedly demonstrated benefits on mood and cognitive performance. These effects were observed when these phytochemicals were consumed separately and in combination. METHODS A review was conducted on 49 human intervention studies to summarize the research on acute psychoactive effects of caffeine, L-theanine, and EGCG on different dimensions of mood and cognitive performance. CONCLUSION Caffeine was found to mainly improve performance on demanding long-duration cognitive tasks and self-reported alertness, arousal, and vigor. Significant effects already occurred at low doses of 40 mg. L-theanine alone improved self-reported relaxation, tension, and calmness starting at 200 mg. L-theanine and caffeine combined were found to particularly improve performance in attention-switching tasks and alertness, but to a lesser extent than caffeine alone. No conclusive evidence relating to effects induced by EGCG could be given since the amount of intervention studies was limited. These studies provided reliable evidence showing that L-theanine and caffeine have clear beneficial effects on sustained attention, memory, and suppression of distraction. Moreover, L-theanine was found to lead to relaxation by reducing caffeine induced arousal.
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Affiliation(s)
- Christina Dietz
- Food Quality and Design Group, Wageningen University, Wageningen, Netherlands
| | - Matthijs Dekker
- Food Quality and Design Group, Wageningen University, Wageningen, Netherlands
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13
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Champlin SE, Pasch KE, Perry CL. Is the Consumption of Energy Drinks Associated With Academic Achievement Among College Students? J Prim Prev 2018; 37:345-59. [PMID: 27236788 DOI: 10.1007/s10935-016-0437-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Despite widely reported side effects, use of energy drinks has increased among college students, who report that they consume energy drinks to help them complete schoolwork. However, little is known about the association between energy drink use and academic performance. We explored the relationship between energy drink consumption and current academic grade point average (GPA) among first-year undergraduate students. Participants included 844 first-year undergraduates (58.1 % female; 50.7 % White). Students reported their health behaviors via an online survey. We measured energy drink consumption with two measures: past month consumption by number of drinks usually consumed in 1 month and number consumed during the last occasion of consumption. We used multiple linear regression modeling with energy drink consumption and current GPA, controlling for gender, race, weekend and weekday sleep duration, perceived stress, perceived stress management, media use, and past month alcohol use. We found that past month energy drink consumption quantity by frequency (p < 0.001), and energy drinks consumed during the last occasion (p < 0.001), were associated with a lower GPA. Energy drinks consumed during the last occasion of consumption (p = 0.01) remained significantly associated with a lower GPA when controlling for alcohol use. While students report using energy drinks for school-related reasons, our findings suggest that greater energy drink consumption is associated with a lower GPA, even after controlling for potential confounding variables. Longitudinal research is needed that addresses whether GPA declines after continued use of energy drinks or if students struggling academically turn to energy drinks to manage their schoolwork.
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Affiliation(s)
- Sara E Champlin
- Department of Kinesiology and Health Education, University of Texas, Austin, 2109 San Jacinto, D3700, Austin, TX, 78712, USA
- Frank W. and Sue Mayborn School of Journalism, University of North Texas, Denton, TX, 76203, USA
| | - Keryn E Pasch
- Department of Kinesiology and Health Education, University of Texas, Austin, 2109 San Jacinto, D3700, Austin, TX, 78712, USA.
| | - Cheryl L Perry
- UT Health, University of Texas Health Science Center at Houston, School of Public Health, Austin Campus, Austin, TX, 78701, USA
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14
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Kerpershoek ML, Antypa N, Van den Berg JF. Evening use of caffeine moderates the relationship between caffeine consumption and subjective sleep quality in students. J Sleep Res 2018; 27:e12670. [PMID: 29479768 DOI: 10.1111/jsr.12670] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 12/22/2017] [Accepted: 01/09/2018] [Indexed: 01/08/2023]
Abstract
Caffeine is often used to reduce sleepiness; however, research suggests that it can also cause poor sleep quality. The timing of caffeine use, amongst other factors, is likely to be important for the effects it has on sleep quality. In addition, individual differences exist in the effect of caffeine on sleep quality. This cross-sectional study investigated the influence of the timing of caffeine consumption on and a possible moderating role of chronotype in the relationship between caffeine consumption and sleep quality in 880 students (74.9% female, mean age 21.3 years, SD = 3.1). Respondents filled in online questionnaires about chronotype (the Morningness-Eveningness Questionnaire), sleep quality (the Pittsburgh Sleep Quality Index) and caffeine consumption. Mean caffeine consumption was 624 mg per week, and 80.2% of the sample drank caffeine after 18:00 hours. Regression analyses demonstrated that higher total caffeine consumption was only related to poorer sleep quality for people who did not drink caffeine in the evening (β = 0.209, p = .006). We did not find a relationship between caffeine and sleep quality in people who drank caffeine in the evening (β = -0.053, p = .160). Furthermore, we found no evidence for a moderating role of chronotype in the relationship between caffeine consumption and sleep quality. We concluded that a self-regulating mechanism is likely to play a role, suggesting that students who know that caffeine negatively affects their sleep quality do not drink it in the evening. Caffeine sensitivity and the speed of caffeine metabolism may be confounding variables in our study.
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Affiliation(s)
| | - Niki Antypa
- Department of Clinical Psychology, Leiden University, Leiden, the Netherlands
| | - Julia F Van den Berg
- Department of Clinical Psychology, Leiden University, Leiden, the Netherlands.,Parnassia Psychiatric Institute, The Hague, the Netherlands
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15
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Temple JL, Hostler D, Martin-Gill C, Moore CG, Weiss PM, Sequeira DJ, Condle JP, Lang ES, Higgins JS, Patterson PD. Systematic Review and Meta-analysis of the Effects of Caffeine in Fatigued Shift Workers: Implications for Emergency Medical Services Personnel. PREHOSP EMERG CARE 2018; 22:37-46. [PMID: 29324066 DOI: 10.1080/10903127.2017.1382624] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
BACKGROUND Emergency Medical Services (EMS) workers may experience fatigue as a consequence of shift work. We reviewed the literature to determine the impact of caffeine as a countermeasure to fatigue in EMS personnel and related shift workers. METHODS We employed the GRADE methodology to perform a systematic literature review and search multiple databases for research that examined the impact of caffeine on outcomes of interest, such as patient and EMS personnel safety. For selected outcomes, we performed a meta-analysis of pooled data and reported the pooled effect in the form of a Standardized Mean Difference (SMD) with corresponding 95% confidence intervals. RESULTS There are no studies that investigate caffeine use and its effects on EMS workers or on patient safety. Four of 8 studies in shift workers showed that caffeine improved psychomotor vigilance, which is important for performance. Caffeine decreased the number of lapses on a standardized test of performance [SMD = 0.75 (95% CI: 0.30 to 1.19), p = 0.001], and lessened the slowing of reaction time at the end of shifts [SMD = 0.52 (95% CI: 0.19 to 0.85); p = 0.002]. Finally, 2 studies reported that caffeine reduced sleep quality and sleep duration. CONCLUSIONS Although the quality of evidence was judged to be low to moderate, when taken together, these studies demonstrate that caffeine can improve psychomotor performance and vigilance. However, caffeine negatively affects sleep quality and sleep duration. More systematic, randomized studies need to be conducted in EMS workers in order to address the critical outcomes of health and safety of EMS personnel and patients. The risk/benefit ratio of chronic caffeine use in shift workers is currently unknown.
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16
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Hughes RN, Hancock NJ. Effects of acute caffeine on anxiety-related behavior in rats chronically exposed to the drug, with some evidence of possible withdrawal-reversal. Behav Brain Res 2016; 321:87-98. [PMID: 28043898 DOI: 10.1016/j.bbr.2016.12.019] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 11/23/2016] [Accepted: 12/15/2016] [Indexed: 01/05/2023]
Abstract
For 20days male and female PVG/c hooded rats were provided with caffeinated (approximately 50mg/kg/day) or unadulterated drinking water, and then their anxiety-related behavior was observed in an open field and elevated plus maze. Their choices of a brightness change were also observed in a Y maze to assess any caffeine effects on spatial memory. 24h later, all rats were tested again following an intraperitoneal injection of 50mg/kg acute caffeine, or vehicle. Earlier chronic caffeine decreased ambulation, walking, rearing, center occupancy and increased immobility in the open field thereby suggesting increased anxiety. However, occupancy of the plus-maze open arms and the Y-maze novel arm were increased by caffeine for male rats, but decreased for females probably because of sex differences in control levels of the response rather than to drug effects on anxiety and memory respectively. Following caffeine withdrawal, acute caffeine had the opposite effect to chronic treatment namely, increased open-field ambulation, walking, center occupancy and decreased immobility and defecation for caffeine-naïve rats that were suggestive of decreased anxiety. Similar but more consistent effects (plus decreased emergence latencies from a darkened start box into the open field) also typified the caffeine-experienced rats which in this case may have been accentuated by caffeine withdrawal-reversal. There was no evidence of either chronic or acute caffeine affecting spatial memory measured in the Y maze. There were also examples of lower overall activity and higher anxiety in male rats, than in females, and some sex-dependent caffeine effects.
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Affiliation(s)
- Robert N Hughes
- Department of Psychology, University of Canterbury, Christchurch 8140, New Zealand.
| | - Nicola J Hancock
- Department of Psychology, University of Canterbury, Christchurch 8140, New Zealand
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Paech GM, Banks S, Pajcin M, Grant C, Johnson K, Kamimori GH, Vedova CBD. Caffeine administration at night during extended wakefulness effectively mitigates performance impairment but not subjective assessments of fatigue and sleepiness. Pharmacol Biochem Behav 2016; 145:27-32. [PMID: 27061779 DOI: 10.1016/j.pbb.2016.03.011] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Revised: 02/28/2016] [Accepted: 03/26/2016] [Indexed: 10/22/2022]
Abstract
The current study investigated the effects of repeated caffeine administration on performance and subjective reports of sleepiness and fatigue during 50h extended wakefulness. Twenty-four, non-smokers aged 22.5±2.9y (mean±SD) remained awake for two nights (50h) in a controlled laboratory environment. During this period, 200mg of caffeine or placebo gum was administered at 01:00, 03:00, 05:00 and 07:00 on both nights (total of 800mg/night). Neurobehavioral performance and subjective reports were assessed throughout the wake period. Caffeine improved performance compared to placebo, but did not affect overall ratings of subjective sleepiness and fatigue. Performance and sleepiness worsened with increasing time awake for both conditions. However, caffeine slowed performance impairments such that after 50h of wakefulness performance was better following caffeine administration compared to placebo. Caffeine also slowed the increase in subjective sleepiness and performance ratings, but only during the first night of wakefulness. After two nights of sleep deprivation, there was no difference in sleepiness ratings between the two conditions. These results demonstrate that strategic administration of caffeine effectively mitigates performance impairments associated with 50h wakefulness but does not improve overall subjective assessments of sleepiness, fatigue and performance. Results indicate that while performance impairment is alleviated, individuals may continue to report feelings of sleepiness. Individuals who use caffeine as a countermeasure in sustained operations may feel as though caffeine is not effective despite impairments in objective performance being largely mitigated.
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Affiliation(s)
- Gemma M Paech
- Centre for Sleep Research, University of South Australia, Adelaide, Australia; Sleep and Performance Research Center and Elson S. Floyd College of Medicine, Washington State University Spokane, WA, United States.
| | - Siobhan Banks
- Centre for Sleep Research, University of South Australia, Adelaide, Australia
| | - Maja Pajcin
- School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, Australia
| | - Crystal Grant
- Centre for Sleep Research, University of South Australia, Adelaide, Australia
| | - Kayla Johnson
- Defence Science and Technology Group, Department of Defence, Edinburgh, Australia
| | - Gary H Kamimori
- Behavioral Biology Branch, Walter Reed Army Institute for Research, Silver Spring, MD, United States
| | - Chris B Della Vedova
- School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, Australia
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Abstract
Caffeine use disorder is included in the conditions for further study section of the DSM-5. Caffeine's profile of neurobiological, behavioral, and clinical effects is similar to other common substances that humans use recreationally. Extant data suggest that a clinically meaningful addictive disorder develops in some regular caffeine users, but this literature is incomplete and not yet sufficient to determine if and how best to define and treat caffeine use disorder. An overview of the literature relevant to determining the clinical importance of problematic caffeine use is followed by discussion of potential concerns and benefits associated with its classification as a mental disorder. Concerns about overdiagnosis and trivialization of other psychiatric syndromes are weighed against the public health benefits of increased awareness and development of interventions targeting problematic caffeine use. This discussion includes consideration of alternative diagnostic approaches, improvement of assessment practices, and the need for additional clinical and epidemiological research.
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Tian DT, Zhou YC, Xiong L, Lu FT. Synthesis and Properties of Caffeine Molecularly Imprinted Polymers Based on Konjac Glucomannan. ADVANCES IN POLYMER TECHNOLOGY 2015. [DOI: 10.1002/adv.21575] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Da-Ting Tian
- School of Chemical and Environmental Engineering; Hubei University for Nationalities; Enshi 445000 People's Republic of China
- Key Laboratory of Biologic Resources Protection and Utilization of Hubei Province; Hubei University for Nationalities; Enshi 445000 People's Republic of China
| | - Yu-Chi Zhou
- School of Chemical and Environmental Engineering; Hubei University for Nationalities; Enshi 445000 People's Republic of China
| | - Ling Xiong
- School of Chemical and Environmental Engineering; Hubei University for Nationalities; Enshi 445000 People's Republic of China
| | - Fang-Ting Lu
- School of Chemical and Environmental Engineering; Hubei University for Nationalities; Enshi 445000 People's Republic of China
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20
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Hussain SJ, Cole KJ. No Enhancement of 24-Hour Visuomotor Skill Retention by Post-Practice Caffeine Administration. PLoS One 2015; 10:e0129543. [PMID: 26053288 PMCID: PMC4459824 DOI: 10.1371/journal.pone.0129543] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 05/11/2015] [Indexed: 01/31/2023] Open
Abstract
Caffeine is widely consumed throughout the world and appears to indirectly facilitate learning and memory through effects on attention and motivation. Animal work indicates that post-training caffeine administration augments inhibitory avoidance memory, spatial memory, and object memory. In humans, post-training caffeine administration enhances the ability to discern between familiar images and new, similar images. However, the effect of post-training caffeine administration on motor memory has not been examined. Therefore, we tested two groups of low caffeine consumers (average weekly consumption ≤500 mg) in a double-blind, placebo-controlled study involving acquisition of a continuous isometric visuomotor tracking skill. On Day 1, subjects completed 5 blocks (150 repetitions) of training on the continuous isometric visuomotor skill and subsequently ingested either 200 mg of caffeine or placebo. On day 2, subjects completed an additional 5 blocks of training. Day 1 mean performance and performance variability were both similar between groups, suggesting that both groups acquired the motor skill similarly. For mean performance on Day 2, patterns of re-learning, mean performance learning magnitudes, mean performance learning rates, and mean performance retention magnitudes were all similar between groups. For performance variability on Day 2, there was a small trend towards increased variability in the caffeine group during re-learning, but performance variability learning magnitudes and performance variability retention magnitudes did not differ between groups. Because motor skill acquisition can also be conceptualized as a reduction in performance variability, these results suggest that there may be a small negative effect of post-practice caffeine administration on memory of a newly-learned visuomotor skill. Overall, we found no evidence to suggest that post-training caffeine administration enhances 24-hour retention of a newly-learned continuous visuomotor skill, and these results support the notion that memory-enhancing effects of post-training caffeine ingestion may be task-specific.
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Affiliation(s)
- Sara J. Hussain
- Department of Health and Human Physiology, University of Iowa, Iowa City, Iowa, United States of America
- * E-mail:
| | - Kelly J. Cole
- Department of Health and Human Physiology, University of Iowa, Iowa City, Iowa, United States of America
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21
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Dodd FL, Kennedy DO, Riby LM, Haskell-Ramsay CF. A double-blind, placebo-controlled study evaluating the effects of caffeine and L-theanine both alone and in combination on cerebral blood flow, cognition and mood. Psychopharmacology (Berl) 2015; 232:2563-76. [PMID: 25761837 PMCID: PMC4480845 DOI: 10.1007/s00213-015-3895-0] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Accepted: 02/11/2015] [Indexed: 01/09/2023]
Abstract
RATIONALE Evidence suggests interactive effects of the tea components caffeine and L-theanine on behaviour, yet no data exists exploring the impact of the two on cerebral blood flow (CBF). OBJECTIVES The current placebo-controlled, double-blind, counterbalanced, crossover study examined the effects of caffeine and L-theanine on CBF and extended previous cognitive and mood findings by using lower doses than previous studies of a similar methodology, which more closely reflect the ratios present in tea. METHODS Twelve habitual consumers and 12 non-habitual consumers of caffeine each received 75 mg caffeine, 50 mg L-theanine, 75 mg caffeine plus 50 mg L-theanine, and placebo in a counterbalanced order across four separate visits. CBF was measured via near-infrared spectroscopy with cognition and mood assessed at baseline and 30 min post-dose. Salivary caffeine and peripheral haemodynamics were co-monitored. RESULTS Caffeine reduced oxygenated haemoglobin (oxy-Hb), increased deoxygenated haemoglobin (deoxy-Hb), improved performance on attention tasks and increased overall mood ratings. Increases in deoxy-Hb following caffeine were more pronounced in non-consumers. Some evidence for increased deoxy-Hb remained when caffeine was combined with L-theanine, but this effect was attenuated and the effects of caffeine on oxy-Hb, cognition and mood were eradicated. CONCLUSIONS Combining L-theanine with caffeine, at levels and ratios equivalent to one to two cups of tea, eliminated the vasoconstrictive effect and behavioural effects of caffeine. This supports previous findings of an interaction between these substances, despite a lack of effects of L-theanine in isolation. However, at the levels tested here, this did not lead to a positive impact on behaviour.
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Affiliation(s)
- F. L. Dodd
- Brain, Performance and Nutrition Research Centre, Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, NE1 8ST UK
| | - D. O. Kennedy
- Brain, Performance and Nutrition Research Centre, Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, NE1 8ST UK
| | - L. M. Riby
- Brain, Performance and Nutrition Research Centre, Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, NE1 8ST UK
| | - C. F. Haskell-Ramsay
- Brain, Performance and Nutrition Research Centre, Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, NE1 8ST UK
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22
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James JE. Caffeine and Cognitive Performance: In Search of Balance in Scientific Opinion and Debate. JOURNAL OF CAFFEINE RESEARCH 2014. [DOI: 10.1089/jcr.2014.0025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Jack E James
- Reykjavík University, Iceland, and National University of Ireland, Galway, Ireland
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23
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Selected Literature Watch. JOURNAL OF CAFFEINE RESEARCH 2014. [DOI: 10.1089/jcr.2014.1243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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