Drinking 2 to 3 cups of caffeinated coffee or 1 to 2 cups of tea daily was associated with a lower risk of dementia and modestly better cognitive function in a prospective cohort study with up to 43 years of follow-up.
The study included 131,821 participants from the Nurses' Health Study (NHS) and Health Professionals Follow-up Study. Researchers documented 11,033 cases of incident dementia during the follow-up period. After adjusting for confounders, patients in the highest quartile of caffeinated coffee consumption had 0.82 times the likelihood of developing dementia compared with those in the lowest quartile. The incidence rate was 141 per 100,000 person-years in the highest consumption group vs 330 per 100,000 person-years in the lowest.
Higher tea intake showed similar associations. Patients in the highest tertile of tea consumption had 0.86 times the likelihood of dementia compared with the lowest tertile. Decaffeinated coffee intake showed no significant association with dementia risk.
The researchers assessed subjective cognitive decline using questionnaire-based scores and objective cognitive function through telephone-based neuropsychological tests. The prevalence of subjective cognitive decline was 8% among patients in the highest quartile of caffeinated coffee intake vs 10% in the lowest quartile. On objective testing in the NHS cohort, patients in the highest caffeine intake quartile had a mean Telephone Interview for Cognitive Status score 0.11 points higher than those in the lowest quartile, equivalent to approximately 0.6 years of cognitive aging. The association with global cognition scores did not reach statistical significance.
Dose-response analyses revealed nonlinear inverse associations. Consumption of approximately 2 to 3 cups per day of caffeinated coffee or 300 mg per day of caffeine was associated with the lowest dementia risk compared with no consumption, with no additional benefit observed at higher intake levels.
The associations remained consistent across subgroups defined by APOE4 genotype, Alzheimer disease polygenic risk score, body mass index, and smoking status. However, inverse associations with dementia risk were stronger among participants aged 75 years or younger compared with older participants.
Study limitations included reliance on food frequency questionnaires that did not capture specific tea types or coffee preparation methods, and dementia ascertainment based on death records and self-reported physician diagnoses may have resulted in misclassification. Potential reverse causation remains possible despite sensitivity analyses, and objective cognitive outcomes were measured only in the NHS cohort without independent replication.
"Greater consumption of caffeinated coffee and tea was associated with lower risk of dementia and modestly better cognitive function, with the most pronounced association at moderate intake levels," the authors concluded.
One contributor reported receiving research support from the Analysis Group. No other conflicts were reported.
Source: JAMA
