People who drink a small number of teas or coffees each day appear to have a lower risk of dementia, researchers say. A large US study found that those who drank two to three cups of caffeinated coffee or one to two cups of caffeinated tea daily had a 15–20% lower dementia risk over four decades than non-drinkers. The findings, published in Journal of the American Medical Association, also showed slightly better cognitive performance among caffeinated coffee drinkers compared with those choosing decaf.
The analysis followed more than 130,000 participants from two long-running health studies and tracked diet, cognition, and dementia diagnoses for up to 43 years. No protective effect appeared for decaffeinated coffee, and benefits seemed to level off beyond moderate intake. Lead author Yu Zhang of Harvard University said the study could not prove cause and effect, but the results matched biological theories linking caffeine and plant compounds to reduced inflammation and better vascular health. Experts cautioned that caffeine has mixed effects and stressed that exercise, diet, sleep, and blood pressure control remain central to protecting brain health.
