Coffee and Tea: How Moderate Consumption Reduces Dementia Risk

A study published in JAMA indicates that moderate consumption of caffeinated coffee and tea is associated with a lower risk of dementia and modestly better cognitive function. The research suggests that these benefits are most pronounced at moderate intake levels, specifically two to three cups of caffeinated coffee or one to two cups of tea daily.

According to a Feb 9, 2026, press release from Mass General Brigham, the findings revealed that both male and female participants with the highest intake of caffeinated coffee experienced an 18% lower risk of dementia compared to those with the lowest intake.

Study Scope and Methodology

The findings are the result of a large prospective cohort study conducted by investigators from Mass General Brigham, the Harvard T.H. Chan School of Public Health and the Broad Institute of MIT and Harvard. The research analyzed data from 131,821 participants across two major cohorts: the Nurses’ Health Study (NHS), which included 86,606 female participants with data from 1980 to 2023, and the Health Professionals Follow-up Study (HPFS), which included 45,215 male participants with data from 1986 to 2023.

To ensure the accuracy of the baseline, the study excluded individuals who already had cancer, Parkinson disease, or dementia at the start of the study. Researchers collected dietary intake data every two to four years using validated food frequency questionnaires, specifically differentiating between the intake of caffeinated coffee, decaffeinated coffee, and tea.

The study tracked participants for up to 43 years, with a median follow-up period of 36.8 years. During this timeframe, researchers identified 11,033 cases of incident dementia through physician diagnoses and death records.

Cognitive Function and Secondary Outcomes

Beyond the primary outcome of dementia risk, the study examined secondary measures of cognitive health. One such measure was subjective cognitive decline, which was assessed via a questionnaire-based score ranging from 0 to 7. In this metric, higher scores indicated a greater perceived decline, with cases defined as those scoring 3 or higher.

Objective cognitive function was also measured specifically within the NHS cohort. This was conducted using telephone-based neuropsychological tests, including the Telephone Interview for Cognitive Status (TICS) score, which ranges from 0 to 41. Researchers utilized a standardized mean z score for six administered cognitive tests to measure global cognition.

The results indicated that moderate consumption of caffeinated beverages not only associated with a lower risk of dementia but also helped in slowing cognitive decline and preserving overall cognitive function.

Clinical Context and Limitations

While the results are encouraging, researchers emphasize that these findings should be viewed as part of a broader approach to brain health. The study highlighted that the differentiation between caffeinated and decaffeinated coffee was a critical component of the research, as previous evidence linking coffee to cognitive health had remained inconclusive due to a failure to separate the two.

While our results are encouraging, it’s important to remember that the effect size is small and You’ll see lots of important ways to protect cognitive function as we age. Our study suggests that caffeinated coffee or tea consumption can be one piece of that puzzle.

Daniel Wang, MD, ScD, associate scientist with the Channing Division of Network Medicine in the Mass General Brigham Department of Medicine

Dr. Wang also noted that early prevention is particularly critical for dementia because current medical treatments are limited and typically provide only modest benefits once symptoms have already appeared.

The study concludes that while moderate intake of caffeinated coffee and tea is associated with positive cognitive outcomes, it is one of many factors involved in protecting cognitive function during the aging process.