USA: A new study has found that moderate daily intake of caffeinated coffee or tea is associated with a lower risk of dementia and better cognitive performance over time. The greatest benefit was seen with 2–3 cups of caffeinated coffee or 1–2 cups of tea per day, while decaffeinated coffee showed no protective effect on dementia risk or cognitive outcomes.
The findings are from a large, long-term prospective cohort study published in
JAMA by Yu Zhang from the Department of Nutrition at the T.H. Chan School of Public Health, Harvard University, Boston, and colleagues. The study aimed to clarify the relationship between coffee and tea consumption and cognitive health, an area where prior evidence has remained inconsistent, particularly due to limited distinction between caffeinated and decaffeinated coffee.
The analysis included 131,821 adults drawn from two well-established US cohorts: the Nurses’ Health Study (NHS) and the Health Professionals Follow-up Study (HPFS). Female participants from the NHS were followed from 1980 to 2023, while male participants from the HPFS were followed from 1986 to 2023. Individuals with a history of cancer, Parkinson’s disease, or dementia at baseline were excluded. Dietary habits, including intake of caffeinated and decaffeinated coffee and tea, were assessed every 2 to 4 years using validated food frequency questionnaires.
The study led to the following findings:
Over a median follow-up of nearly 37 years, a total of 11,033 incident dementia cases were recorded across both cohorts.
After adjustment for multiple confounding factors, higher intake of caffeinated coffee was consistently linked to a reduced risk of dementia.
Participants in the highest quartile of caffeinated coffee consumption had 141 dementia cases per 100,000 person-years, compared with 330 cases per 100,000 person-years in the lowest quartile.
This difference corresponded to an 18% lower risk of developing dementia among those with higher caffeinated coffee intake.
Greater consumption of caffeinated coffee was also associated with more favorable cognitive outcomes over time.
The prevalence of subjective cognitive decline was lower among individuals with higher levels of caffeinated coffee intake.
In the Nurses’ Health Study cohort, objective cognitive assessments showed modest improvements in Telephone Interview for Cognitive Status scores and overall cognitive performance among higher coffee consumers.
Tea consumption demonstrated similar inverse associations with dementia risk and cognitive decline.
Decaffeinated coffee intake was not associated with a lower risk of dementia or better cognitive performance, highlighting a potential role of caffeine in the observed benefits.
Dose-response analyses revealed nonlinear relationships, with the strongest associations seen at moderate intake levels rather than very high consumption. According to the authors, these findings indicate that regular, moderate consumption of caffeinated coffee or tea may be linked to healthier cognitive aging.
While the study does not establish causality, its long follow-up period, large sample size, and repeated dietary assessments strengthen the evidence supporting a protective association between caffeinated beverages and cognitive health.
Reference:
Zhang Y, Liu Y, Li Y, et al. Coffee and Tea Intake, Dementia Risk, and Cognitive Function. JAMA. Published online February 09, 2026. doi:10.1001/jama.2025.27259
