Caffeinated Coffee and Tea Consumption, Genetic Variation and Cognitive Function in the UK Biobank.

BACKGROUND: Coffee and tea are the major contributors of caffeine in the diet. Evidence points to the premise that caffeine may benefit cognition. OBJECTIVE: We examined the associations of habitual regular coffee or tea and caffeine intake with cognitive function whilst additionally accounting for genetic variation in caffeine metabolism. METHODS: We included white participants aged 37-73 y from the UK Biobank who provided biological samples and completed touchscreen questionnaires regarding sociodemographic factors, medical history, lifestyle, and diet. Habitual caffeine-containing coffee and tea intake was self-reported in cups/day and used to estimate caffeine intake. Between 97,369 and 445,786 participants with data also completed ≥1 of 7 self-administered cognitive functioning tests using a touchscreen system (2006-2010) or on home computers (2014). Multivariable regressions were used to examine the association between coffee, tea, or caffeine intake and cognition test scores. We also tested interactions between coffee, tea, or caffeine intake and a genetic-based caffeine-metabolism score (CMS) on cognitive function. RESULTS: After multivariable adjustment, reaction time, Pairs Matching, Trail Making test B, and symbol digit substitution, performance significantly decreased with consumption of 1 or more cups of coffee (all tests P-trend < 0.0001). Tea consumption was associated with poor performance on all tests (P-trend < 0.0001). No statistically significant CMS × tea, CMS × coffee, or CMS × caffeine interactions were observed. CONCLUSIONS: Our findings, based on the participants of the UK Biobank, provide little support for habitual consumption of regular coffee or tea and caffeine in improving cognitive function. On the contrary, we observed decrements in performance with intakes of these beverages which may be a result of confounding. Whether habitual caffeine intake affects cognitive function therefore remains to be tested.