Overview
- A Harvard- and Mass General–led team pooled Nurses’ Health Study and Health Professionals Follow-Up Study data (n≈131,821) with follow-up up to 43 years, publishing the results in JAMA.
- Higher midlife intake of caffeinated coffee or tea was associated with fewer dementia diagnoses, with the strongest signal at about two to three cups of coffee or one to two cups of tea per day.
- Decaffeinated coffee showed no protective association in the analyses.
- The magnitude was modest, with examples such as 141 versus 330 cases per 100,000 in some comparisons, and cognitive test differences were minimal.
- Researchers and outside experts emphasize the findings are observational and non-causal, urging focus on established measures like exercise, sleep, and cardiovascular risk control as lab mechanisms remain preclinical.