Coffee may support brain health, long-term study suggests

A 43-year analysis of 131,821 US health professionals published in JAMA found that higher intake of caffeinated coffee and tea was associated with lower dementia risk and modestly better cognitive scores; the study is observational and does not prove causation.

Researchers followed participants in two large US cohorts for 43 years to examine links between beverage intake and cognitive outcomes. The analysis, published in JAMA and led by investigators at the Harvard T.H. Chan School of Public Health, compared caffeinated coffee, decaffeinated coffee and tea intake. Participants reported diet repeatedly over the study period, and researchers tracked dementia diagnoses, self-reported memory decline and, for a subgroup, formal cognitive testing. The report emphasizes associations rather than cause and effect. Key findings: - The pooled sample included 86,606 women from the Nurses' Health Study and 45,215 men from the Health Professionals Follow-Up Study, for 131,821 total participants followed for 43 years. - Over the study period 11,033 participants developed dementia. - Higher versus lower intakes of caffeinated coffee were associated with an 18 per cent lower dementia risk and a 15 per cent lower likelihood of self-reported cognitive decline; higher caffeinated coffee intake was also linked with better cognitive test performance. - Higher intakes of tea showed a similar pattern, with the most pronounced associations at about two to three cups of caffeinated coffee per day or one to two cups of tea per day. - There was no observed relationship between decaffeinated coffee and dementia risk or cognitive decline, and measured caffeine intake showed associations similar to caffeinated coffee. - The researchers adjusted for multiple factors including family history, lifestyle, cardiometabolic conditions and APOE4 status, but the study is observational and cannot establish causation. Summary: The study adds to previous research suggesting a link between habitual caffeinated coffee or tea intake and lower dementia risk, and it reports specific association strengths and commonly consumed intake levels. Undetermined at this time.