People who drink a couple of teas or coffees a day may face a lower risk of dementia and slightly slower cognitive decline, scientists say. A large US study of more than 130,000 people 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 were published in Journal of the American Medical Association.
Researchers analysed long-term data from the Nurses’ Health Study and the Health Professionals Follow-up Study. Caffeinated coffee drinkers also showed slightly better cognitive test results than those who chose decaf, which showed no benefit. Lead author Yu Zhang of Harvard University said the study could not prove cause and effect but offered the strongest evidence so far.
Experts caution that caffeine has mixed effects, including raising blood pressure in some people. Naveed Sattar of the University of Glasgow said only long-term trials could confirm true benefits. Researchers stress that tea or coffee should complement, not replace, healthy habits such as exercise, good sleep and balanced diets.
