People who drink a couple of teas or coffees a day may have a lower risk of dementia and slightly better cognitive performance, researchers say. A large US study tracking more than 130,000 people for up to 40 years 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 than non-drinkers. The findings, published in the Journal of the American Medical Association, also showed marginally less cognitive decline among coffee drinkers compared with those choosing decaf.
The research drew on data from the Nurses’ Health Study and the Health Professionals Follow-up Study and was led by Yu Zhang of Harvard University. Zhang said the results did not prove causation, as other lifestyle factors could explain the link. Tea and coffee contain caffeine and polyphenols that may support brain health by reducing inflammation, improving blood vessel function, and lowering diabetes risk. Experts cautioned that caffeine can also raise blood pressure in some people, which increases dementia risk. Prof Naveed Sattar of the University of Glasgow said only long-term trials could confirm a protective effect. Researchers stressed that tea and coffee should not replace broader healthy habits such as exercise, good sleep, and a balanced diet.
