People who drink tea or coffee daily show a lower risk of dementia, scientists report.
Researchers analysed health data from more than 130,000 US adults followed for up to 43 years.
Those who drank two to three cups of caffeinated coffee or one to two cups of tea daily had a 15–20% lower dementia risk.
Caffeinated coffee drinkers also showed slightly less cognitive decline than non-drinkers.
The study appeared in the Journal of the American Medical Association.
No protective effect emerged for decaffeinated coffee.
Lead author Yu Zhang from Harvard University said the results could not prove cause and effect.
Caffeine drinkers may differ in lifestyle or health from non-drinkers.
Researchers believe caffeine and plant compounds may protect brain health by reducing inflammation and improving blood flow.
Experts stress tea and coffee are not substitutes for exercise, sleep, and healthy living.
