Coffee and tea linked with lower dementia risk in long-term study

A long-term observational study of about 132,000 U.S. health professionals found that drinking 2–3 cups of caffeinated coffee or 1–2 cups of tea daily was associated with a lower dementia risk and slightly better cognitive performance; decaffeinated coffee did not show the same association.

A long-term observational study reported in the Journal of the American Medical Association examined caffeine habits and cognitive outcomes in nearly 132,000 U.S. health professionals. Researchers combined data from the Nurses' Health Study and the Health Professionals Follow-Up Study covering 1980–2023. Over a median follow-up of about 37 years, higher intake of caffeinated coffee or tea was associated with lower rates of dementia and modestly better performance on some cognitive tests. Decaffeinated coffee did not show the same association. Key findings: - The analysis pooled roughly 132,000 participants: more than 86,000 women from the Nurses' Health Study and more than 45,000 men from the Health Professionals Follow-Up Study. - Median follow-up was about 37 years, during which more than 11,000 participants were diagnosed with dementia. - Compared with non-drinkers, the lowest dementia risk was observed for about 2–3 cups of caffeinated coffee per day or 1–2 cups of tea per day, estimated at roughly 300 mg of caffeine. - Participants with the highest caffeinated coffee intake had an 18% lower dementia risk and those with the highest tea intake had a 14% lower risk versus the lowest intake; associations were stronger among people aged 75 and younger. - The association persisted among people carrying the APOE4 genetic risk factor; the study did not find similar neuroprotective associations for decaffeinated coffee. Summary: The study reports an association between habitual caffeinated coffee or tea intake and lower dementia risk and modestly better cognitive measures, but it is observational and does not establish causation. Authors and outside experts noted limitations including reliance on self‑reported diet, unspecified coffee and tea types and preparation methods, and uneven cognitive testing across groups. Further research is needed to clarify which components or patterns underlie the observed associations.