Caffeinated coffee, tea good for the brain

New research suggests that moderate intake levels of caffeinated coffee and tea may reduce the risk of dementia and produce modest improvements in cognitive function.

Over a median follow-up of 36.8 years, participants in the highest vs lowest intake quartile of caffeinated coffee had an 18-percent lower risk of dementia (141 vs 330 cases per 100,000 person-years; hazard ratio [HR], 0.82, 95 percent confidence interval [CI], 0.76–0.89; p<0.001). [JAMA 2026;doi:10.1001/jama.2025.27259]

Additionally, participants in the highest vs lowest intake quartile of caffeinated coffee had lower prevalence of subjective cognitive decline (7.8 percent vs 9.5 percent; prevalence ratio, 0.85, 95 percent CI, 0.78–0.93; p<0.001) and modestly better objective cognitive performance assessed using the Telephone Interview for Cognitive Status (TICS) (mean difference in TICS score, 0.11, 95 percent CI, 0.01–0.21; p=0.03).

Similar observations were made for tea, with the top intake tertile being associated with reduced risk of dementia (HR, 0.86, 95 percent CI, 0.83–0.90; p<0.001), lower prevalence of subjective cognitive decline (prevalence ratio, 0.86, 95 percent CI, 0.80–0.93; p<0.001), and better objective cognitive performance (mean difference, 0.16, 95 percent CI, 0.08–0.25; p=0.001).

A dose-response analysis showed nonlinear inverse associations between caffeinated coffee and tea consumption and dementia risk and subjective cognitive decline. The strongest associations were observed at moderate consumption levels, approximately 2–3 cups per day of caffeinated coffee or 1–2 cups per day of tea. Consumption levels exceeding these provided no additional benefits.

“The [nonlinear] pattern [of association] is biologically plausible because the absorption, transportation, metabolism, and storage of caffeine and other bioactive compounds in coffee and tea have physiological limits,” the investigators noted. [Pharmacol Rev 2018;70:384-411]

“Specifically, enzymatic activities in caffeine metabolism (particularly those activities mediated by CYP1A2) may saturate at higher doses, contributing to this threshold effect. Moreover, excessive caffeine intake may negatively affect sleep quality or increase anxiety, potentially offsetting its possible neuroprotective benefits,” they explained. [Curr Drug Metab 2021;22:40-49; N Engl J Med 2020;383:369-378] 

The signal of benefit observed with the intake of caffeinated coffee and tea may have important implications, given the rising number of people with Alzheimer’s disease as well as the limited treatment options and potential adverse effects of available therapies, the investigators said. “Early prevention is crucial.”

A total of 86,606 female participants (mean age 46.2 years) from the Nurses’ Health Study (NHS) and 45,215 male participants (mean age 53.8 years) from the Health Professionals Follow-up Study were included in the study. Dietary intake was collected every 2 to 4 years using validated food frequency questionnaires.

The primary outcome of dementia was identified via death records and physician diagnoses. Secondary outcomes were subjective cognitive decline and objective cognitive function. Objective cognitive function was assessed only in the NHS cohort.