LAUSR

Coffee is a highly popular beverage worldwide, containing caffeine which is a central nervous system stimulant. The aim was to examine whether habitual coffee consumption is associated with differences in brain volumes or the risk odds of dementia or stroke. Prospective analyses of habitual coffee consumption were conducted in 398,646 participants (age 37-73 years) within the UK Biobank, including 17,702 participants with volumetric MRI information. We examined associations between coffee consumption and brain volume using covariate adjusted linear regression, and with odds of dementia and stroke using logistic regression. All participants were free of dementia and stroke at baseline. We obtained 4,333 incident dementia and 6,181 incident stroke cases. There were inverse linear associations between coffee consumption and total brain (β per cup -1·42, p = 1·4x10-8), grey matter (-0·92, p = 5·2x10-10), white matter (-0·50, p = 0·002) and hippocampal volumes (-0·01, p = 0·009), but no evidence to support associations with white matter hyperintensity volume (-0·01, p = 0·72). After full covariate adjustment, consumption of > 6 cups/day of coffee was associated with 53% higher odds of dementia compared to consumption of 1-2 cups/day (OR 1.53, 95% CI 1.28, 1.83), with less evidence for an association with stroke (OR 1.17, 95% CI 1.00, 1.37, p = 0.055). High coffee consumption was associated with smaller total brain volumes and increased odds of dementia. The findings suggest caution at higher levels of coffee consumption, however further studies are required to establish causality, and to explore the clinical relevance of brain volume changes.