REVIEW OF: Pham K et al, Nutr Neurosci 2022;25(10):2111–2122

STUDY TYPE: Prospective cohort study

How does coffee affect the brain and the risk of dementia? To date, a few studies have been published with mixed findings. A new long-term prospective study, the largest of its kind, looked at a British database of 398,646 White adults aged 37–73 years in the UK Biobank, of which 17,702 had brain MRI data available. Researchers examined the association between coffee consumption and brain volume, as well as dementia (4,333 incident cases) and stroke (6,181 incident cases).

The study found that higher coffee consumption was generally associated with smaller brain volumes—including total brain, gray matter, white matter, and hippocampal volumes. Coffee consumption was not associated with white matter hyperintensity volume. The study also found an association between coffee consumption and the odds of dementia: Drinking more than six cups daily was associated with 53% higher odds of dementia. There was less evidence for an association between coffee consumption and stroke.

The study’s limitations include reliance on self-reported data regarding coffee consumption, which is further complicated by the lack of a standard definition for a unit of coffee. And since the study included only White, British individuals, the findings don’t necessarily generalize to other populations.

Carlat Take

This study’s findings are consistent with high caffeine use correlating with dementia, but on the other hand, people who notice cognitive decline might drink more coffee to try to stimulate their memory. As with similar observational studies, it’s impossible to know the direction of causality. Nonetheless, this study highlights that there is a potential neurobiological risk from drinking more than six cups of coffee daily. When patients bring up questions about their coffee use, in addition to describing coffee’s effects on anxiety and sleep, we can discuss its association with lower brain volume and dementia. This may help motivate patients to drink coffee in moderation.