Coffee and dementia: Moderate daily intake of caffeinated coffee or tea may be linked to a lower risk of dementia and slightly better cognitive performance over time, according to a large, decades-long observational study tracking nearly 132,000 US health professionals.
Researchers analysed dietary and health data from two long-running cohorts spanning 1980 to 2023: the Nurses’ Health Study (women) and the Health Professionals Follow-up Study (men). Participants completed diet questionnaires every 2 to 4 years, including their intake of regular and decaf coffee and tea. After a median follow-up of almost 37 years, more than 11,000 participants had developed dementia.
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The strongest association was seen with moderate consumption. Compared with non-drinkers, the lowest dementia risk was observed among those who drank two to three cups of caffeinated coffee a day or one to two cups of tea a day, roughly 300 mg of caffeine in total. Decaffeinated coffee did not show the same pattern.
When comparing the highest and lowest intake groups, heavy caffeinated coffee drinkers had an 18% lower dementia risk, while the highest tea consumers had a 14% lower risk. The study also reported fewer subjective memory complaints and modestly better scores on cognitive tests among higher coffee and tea consumers, with the association appearing stronger in people aged 75 and under.
The relationship held even among participants at higher genetic risk for dementia, including those with APOE4, a major risk factor for Alzheimer’s disease.
Researchers and outside experts stressed that the results show an association, not proof that caffeine prevents dementia. They also noted limitations, including limited detail on tea types and coffee preparation methods, and the challenge of separating caffeine’s effects from other compounds in coffee and tea, such as polyphenols.