Caffeine and cognitive performance: Persistent methodological challenges in caffeine research

Human cognitive performance is widely perceived to be enhanced by caffeine at usual dietary doses. However, the evidence for and against this belief continues to be vigorously contested. Controversy has centred on caffeine withdrawal and withdrawal reversal as potential sources of experimental confo...

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Bibliographic Details
Published in:Pharmacology, biochemistry and behavior biochemistry and behavior, 2014-09, Vol.124, p.117-122
Main Author: James, Jack E.
Format: Article
Language:English
Subjects:
Caffeine
Caffeine - adverse effects
Caffeine - pharmacology
Caffeine-naïve
Cognition - drug effects
Cognitive performance
Humans
Methodological challenges
Placebo control
Substance Withdrawal Syndrome
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Summary:Human cognitive performance is widely perceived to be enhanced by caffeine at usual dietary doses. However, the evidence for and against this belief continues to be vigorously contested. Controversy has centred on caffeine withdrawal and withdrawal reversal as potential sources of experimental confounding. In response, some researchers have enlisted “caffeine-naïve” experimental participants (persons alleged to consume little or no caffeine) assuming that they are not subject to withdrawal. This mini-review examines relevant research to illustrate general methodological challenges that have been the cause of enduring confusion in caffeine research. At issue are the processes of caffeine withdrawal and withdrawal reversal, the definition of caffeine-naïve, the population representativeness of participants deemed to be caffeine-naïve, and confounding due to caffeine tolerance. Attention to these processes is necessary if premature conclusions are to be avoided, and if caffeine's complex effects and the mechanisms responsible for those effects are to be illuminated. Strategies are described for future caffeine research aimed at minimising confounding from withdrawal and withdrawal reversal. •Controversy surrounds claims of caffeine enhancement of cognitive performance.•Caffeine withdrawal and withdrawal reversal have been sources of serious confounding.•Confounding is reputedly avoided by observing “caffeine-naïve” participants.•Caffeine-naïve participants do not remove threats to internal and external validity.•Strategies are described for minimising confounding in future caffeine research.
ISSN:0091-3057
1873-5177
DOI:10.1016/j.pbb.2014.05.019