NEW long-term data suggest that higher intake of caffeinated coffee and tea is associated with a lower risk of dementia and modestly better cognitive performance, while decaffeinated coffee appears to offer no such benefit.
The findings come from a large prospective cohort study including more than 130,000 participants followed for up to four decades.
Decades of Follow-Up
Researchers analysed data from two major US cohorts: the Nurses’ Health Study and the Health Professionals Follow-up Study. Together, these cohorts provided dietary and health data from 131,821 individuals who were free of dementia, Parkinson disease, and cancer at baseline.
Dietary intake of caffeinated coffee, decaffeinated coffee, and tea was assessed every two to four years using validated food frequency questionnaires. Over a median follow-up of nearly 37 years, 11,033 cases of incident dementia were documented.
Caffeinated Coffee Shows Protective Association
After adjustment for potential confounders, higher caffeinated coffee intake was significantly associated with lower dementia risk. Participants in the highest quartile of caffeinated coffee consumption had a 18% lower risk of dementia compared with those in the lowest quartile.
Higher caffeinated coffee intake was also associated with a lower prevalence of subjective cognitive decline. In the Nurses’ Health Study cohort, greater caffeinated coffee consumption was linked to slightly better performance on objective cognitive tests, including the Telephone Interview for Cognitive Status. However, improvements in global cognition scores did not reach statistical significance.
Tea Mirrors the Findings
Tea intake showed similar inverse associations with dementia risk and subjective cognitive decline. The relationship appeared nonlinear, with the most pronounced benefits observed at moderate intake levels—approximately two to three cups per day of caffeinated coffee or one to two cups per day of tea.
In contrast, decaffeinated coffee intake was not significantly associated with dementia risk or cognitive outcomes, suggesting that caffeine or related compounds may play a key role.
Implications and Caution
Although the study cannot establish causality, its long follow-up period and repeated dietary assessments strengthen the reliability of the findings. The results contribute to ongoing debate about the role of dietary factors in cognitive ageing and dementia prevention.
The authors conclude that moderate consumption of caffeinated coffee and tea may be associated with favourable cognitive outcomes, but emphasise that further research is needed to clarify mechanisms and confirm whether these associations reflect causal effects.
For now, the data suggest that for many adults, a daily cup or two of coffee or tea may be part of a lifestyle associated with healthier cognitive ageing.
Reference
Zhang Y et al. Coffee and Tea Intake, Dementia Risk, and Cognitive Function. JAMA. 2026;DOI:10.1001/jama.2025.27259.
