Drinking a couple of teas or coffees a day may lower the risk of dementia and slow cognitive decline, scientists say. A large US study found that people 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 research analysed health data from more than 130,000 people followed for up to four decades and was published in the Journal of the American Medical Association.
Caffeinated coffee drinkers also showed slightly better performance on cognitive tests than those who drank decaf. No protective effect appeared for decaffeinated coffee. Lead author Yu Zhang of Harvard University said the findings could not prove cause and effect, but were consistent with known biology. Caffeine and polyphenols in tea and coffee may protect the brain by reducing inflammation, improving blood vessel health, and supporting metabolism.
Experts caution that caffeine has mixed effects and may raise blood pressure in some people. Researchers stress that tea and coffee are not a substitute for a healthy lifestyle, which remains the strongest defence against dementia.
