Drinking a couple of teas or coffees a day may lower the risk of dementia and slightly slow cognitive decline, scientists say. A large US study found that people who regularly drank two to three cups of caffeinated coffee or one to two cups of caffeinated tea had a 15–20% lower risk of dementia over four decades than those who avoided the drinks. The research analysed health data from more than 130,000 participants and was published in Journal of the American Medical Association.
Caffeinated coffee drinkers also showed marginally better performance on some cognitive tests than those who drank decaf, which showed no link to dementia risk. Lead author Yu Zhang of Harvard University said the study could not prove cause and effect, but the findings matched biological theories. Tea and coffee contain caffeine and polyphenols that may reduce inflammation, improve blood vessel health, and protect against brain ageing.
Experts caution that caffeine has mixed effects and may raise blood pressure in some people, which increases dementia risk. Naveed Sattar said only long-term trials could confirm benefits, though these are difficult to run. Researchers stress that tea and coffee are not a cure-all and that exercise, good sleep, and a healthy diet remain key to protecting brain health.
