Cognitive and mood improvements of caffeine in habitual consumers and habitual non-consumers of caffeine
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The cognitive and mood effects of caffeine are well documented. However, the majority of studies in this area involve caffeine-deprived, habitual caffeine users. It is therefore unclear whether any beneficial findings are due to the positive effects of caffeine or to the alleviation of caffeine withdrawal.
The present placebo-controlled, double-blind, balanced crossover study investigated the acute cognitive and mood effects of caffeine in habitual users and habitual non-users of caffeine.
Following overnight caffeine withdrawal, 24 habitual caffeine consumers (mean=217 mg/day) and 24 habitual non-consumers (20 mg/day) received a 150 ml drink containing either 75 or 150 mg of caffeine or a matching placebo, at intervals of ≥48 h. Cognitive and mood assessments were undertaken at baseline and 30 min post-drink. These included the Cognitive Drug Research computerised test battery, two serial subtraction tasks, a sentence verification task and subjective visual analogue mood scales.
There were no baseline differences between the groups’ mood or performance. Following caffeine, there were significant improvements in simple reaction time, digit vigilance reaction time, numeric working memory reaction time and sentence verification accuracy, irrespective of group. Self-rated mental fatigue was reduced and ratings of alertness were significantly improved by caffeine independent of group. There were also group effects for rapid visual information processing false alarms and spatial memory accuracy with habitual consumers outperforming non-consumers. There was a single significant interaction of group and treatment effects on jittery ratings. Separate analyses of each groups’ responses to caffeine revealed overlapping but differential responses to caffeine. Caffeine tended to benefit consumers’ mood more while improving performance more in the non-consumers.
These results do not support a withdrawal alleviation model. Differences in the patterns of responses to caffeine by habitual consumers and habitual non-consumers may go some way to explaining why some individuals become caffeine consumers.
KeywordsCaffeine Withdrawal Cognition Mood Performance Consumers Non-consumers
- Bond A, Lader M (1974) The use of analogue scales in rating subjective feelings. Br J Psychol 47:211–218Google Scholar
- Gray J (1998) Caffeine, coffee and health. Nutr Food Sci 6:314–319Google Scholar
- Heatherley SV, Sears HE, Hayward RC, Kane M, Rogers PJ (2004) Time-course of mood and performance effects of long-term caffeine withdrawal. Appetite 43:114Google Scholar
- James JE (1994) Does caffeine enhance or merely restore degraded psychomotor performance? Neuropsychobiology 38:32–41Google Scholar
- Kaplan GB, Greenblatt DJ, Ehrenberg BL, Goddard JE, Cotreau MM, Harmatz JS (1997) Dose-dependent pharmacokinetics and psychomotor effects of caffeine in humans. J Clin Pharmacol 37:693–703Google Scholar
- Kennedy DO, Scholey AB (2004) A glucose-caffeine ‘energy drink’ ameliorates subjective and performance deficits during prolonged cognitive demand. Appetite 42:331–333Google Scholar
- Kennedy DO, Scholey AB, Wesnes KA (2002) Modulation of cognition and mood following administration of single doses of Ginkgo biloba, ginseng, and a ginkgo/ginseng combination to healthy young adults. Physiol Behav 75:739–751Google Scholar
- Kennedy DO, Wake G, Savelev S, Tildesley NT, Perry EK, Wesnes KA, Scholey AB (2003) Modulation of mood and cognitive performance following acute administration of single doses of Melissa officinalis (Lemon balm) with human CNS nicotinic and muscarinic receptor-binding properties. Neuropsychopharmacology 28:1871–1881CrossRefPubMedGoogle Scholar
- Keppel G (1991) Designs and analysis: a researcher’s handbook. Prentice-Hall, New JerseyGoogle Scholar
- Loke WH, Meliska CJ (1984) Effects of caffeine use and indigestion on a protracted visual vigilance task. Psychopharmacology 84:54–57Google Scholar
- Mackay M, Tiplady B, Scholey AB (2002) Interactions between alcohol and caffeine in relation to psychomotor speed and accuracy. Hum Psychopharmacol-Clin Exp 17:151–156Google Scholar
- Nguyen-Van-Tam DP (2002) Caffeine and human memory. Ph.D. thesis, University of CardiffGoogle Scholar
- Phillips-Bute BG, Lane JD (1998) Caffeine withdrawal symptoms following brief caffeine deprivation. Physiol Behav 63:327–330Google Scholar
- Reyner LA, Horne JA (2000) Early morning driver sleepiness: effectiveness of 200 mg of caffeine. Psychophysiology 37:251–256Google Scholar
- Scholey AB, Kennedy DO (2004) Cognitive and physiological effects of an ‘energy drink’: an evaluation of the whole drink and of glucose, caffeine and herbal flavouring fractions. Psychopharmacology (in press)Google Scholar
- Swift CG, Tiplady B (1988) The effects of age on the response to caffeine. Psychopharmacology 94:29–31Google Scholar
- Weschler D (1958) The measurement and appraisal of human intelligence, 4th edn. Williams and Wilkins, BaltimoreGoogle Scholar