Overview
- Researchers pooled data from the Nurses’ Health Study and the Health Professionals Follow‑up Study, tracking 131,821 adults for up to 43 years and documenting 11,033 dementia cases.
- Higher intakes of caffeinated coffee and tea were associated with lower risk of dementia, with roughly 18% lower risk for coffee, about 14% for tea, and around 22% for total caffeine intake.
- The strongest association appeared at about two to three cups of caffeinated coffee or one to two cups of tea per day—approximately 300 mg of caffeine—with no added benefit at higher levels.
- Decaffeinated coffee showed no protective association, and the caffeine-related signal held after extensive adjustment for lifestyle and medical factors and across APOE4 genetic risk.
- A subset also showed better cognitive test performance with higher caffeinated coffee intake, but experts emphasize the observational design and advise moderation given caffeine’s potential side effects.