A major Harvard-led study has found that drinking two to three cups of caffeinated coffee daily is linked to a lower dementia risk. Published in JAMA on 9 February 2026, the research drew on data from 131,821 US health professionals tracked for up to 43 years. Those consuming the most caffeinated coffee saw an 18 per cent reduced risk of dementia compared to minimal drinkers, with similar patterns for tea but none for decaf.
The findings held across genders and genetic risks. This adds to growing evidence on how everyday habits might influence brain health as populations age.
Researchers from Mass General Brigham, Harvard T.H. Chan School of Public Health, and the Broad Institute analysed long-term data from the Nurses' Health Study and Health Professionals Follow-Up Study. Participants, 65.7 per cent female with mean baseline ages of 46.2 and 53.8 years, reported dietary habits every four years via questionnaires.
Over a median follow-up of 36.8 years,11,033 developed dementia. Adjustments were made for factors likesmoking, exercise, and education to isolate the effects of coffee and tea. A dose-response curve revealed nonlinear benefits, peaking at moderate levels: aroundtwo to three cups of coffee or one to two cups of tea per dayfor the strongest associations with reduced dementia incidence.
Decaffeinated coffee showed no such links, pointing to caffeine as a likely key player, though polyphenols in both beverages may also contribute by curbing inflammation and oxidative stress. The team highlighted the study's strength in capturing lifelong patterns, addressing gaps in shorter prior research.
Beyond dementia risk, the analysis tied caffeinated coffee and tea to slower cognitive decline and better brain function. High coffee consumers had a lower prevalence of subjective cognitive complaints—7.8 per cent versus 9.5 per centin low consumers—and scored modestly higher on objective tests like the Telephone Interview for Cognitive Status. Tea drinkers mirrored these trends, with optimal intake at lower volumes.
Intriguingly, benefits applied equally to those with high or lowgenetic predisposition to dementia, suggesting broad applicability. While higher intake of up to five cups offered protection without apparent harm, the most pronounced benefits were seen at moderate levels.
Past research on coffee and dementia has yielded mixed results, often due to brief follow-ups or vague intake measures. This study's authors acknowledge a small overall effect size, urging caution. 'While our results are encouraging, it's important to remember that the effect size is small and there are lots of important ways to protect cognitive function as we age,' said senior author Daniel Wang.
Lead author Yu Zhang added that benefits spanned genetic profiles. Further trials are needed to pinpoint mechanisms. This research underscores caffeinated drinks' potential role in dementia prevention strategies.
A large new@harvardstudy finds that 2-3 cups of coffee or tea a day (the caffeinated kind!) protect modestly against dementia. I write this as I drink my coffee, smiling.https://t.co/B29lIDRqor
Source: International Business Times UK
