People who drink a couple of cups of tea or coffee each day may have a lower risk of dementia, scientists say. A long-term US study found that those who regularly drank two to three cups of caffeinated coffee or one to two cups of caffeinated tea had a 15–20% lower dementia risk than non-drinkers. They also showed slightly better cognitive performance over time.
The analysis, published in Journal of the American Medical Association, followed more than 130,000 people for up to four decades. Researchers drew data from two major US health studies and found no similar benefit from decaffeinated coffee. Lead author Yu Zhang of Harvard University said the findings were consistent with biological theories but could not prove cause and effect.
Scientists suggest caffeine and plant compounds in tea and coffee may support brain health by reducing inflammation and improving blood vessel function. However, experts caution that caffeine can also raise blood pressure in some people, which increases dementia risk. Professor Naveed Sattar of the University of Glasgow said only long-term trials could confirm a true protective effect. Researchers stress that tea and coffee should complement, not replace, a healthy lifestyle that includes exercise, good sleep, and balanced nutrition.
