Drinking a moderate amount of coffee or tea each day may do more than boost energy — it could also help protect the brain as we age.
A large long-term study by researchers from Mass General Brigham, Harvard, and the Broad Institute suggests that consuming two to three cups of caffeinated coffee daily is linked to a lower risk of dementia and better cognitive health later in life.
The findings come from an analysis of more than 131,000 participants enrolled in two major U.S. health studies that have tracked diet and health outcomes for over 40 years.
Researchers followed participants’ coffee and tea consumption and compared it with changes in memory, thinking ability, and dementia diagnoses over time.
The results, published in JAMA, indicate that moderate intake of caffeinated beverages may be associated with slower cognitive decline.
Dementia prevention has become a major focus for scientists because treatments available after symptoms appear offer limited benefit.
This has led researchers to explore everyday lifestyle factors, including diet, that might reduce risk. Coffee and tea contain natural compounds such as caffeine and antioxidants called polyphenols, which may help protect brain cells by reducing inflammation and damage.
In the study, more than 11,000 participants developed dementia during the follow-up period. Those who regularly drank caffeinated coffee had an 18 percent lower risk compared with people who rarely or never drank it.
Coffee drinkers also reported fewer early signs of memory decline and performed slightly better on tests of cognitive function.
Tea showed similar protective effects, especially at a consumption level of one to two cups per day. Interestingly, decaffeinated coffee did not produce the same benefits, suggesting that caffeine itself may play an important role. However, scientists say other compounds in these beverages could also contribute, and more research is needed to understand the exact mechanisms.
The strongest benefits appeared among people who consumed moderate amounts — two to three cups of coffee daily or one to two cups of tea. Drinking more did not appear to cause harm in this study, but it also did not provide significantly greater protection.
Researchers also looked at genetic risk for dementia and found that the association between coffee consumption and lower risk was similar regardless of whether participants were genetically predisposed to the disease. This suggests that the potential benefits of moderate caffeine intake may apply broadly across different groups.
Experts caution that coffee and tea alone cannot prevent dementia. Brain health depends on many factors, including exercise, sleep, social engagement, and overall diet. Still, the findings suggest that a simple daily habit enjoyed by millions could be one helpful piece of a larger prevention strategy.
While the effect observed in the study was modest, researchers say the widespread popularity of coffee and tea means even small benefits could have a meaningful impact at the population level. For many people, enjoying a morning cup may now come with the added comfort of knowing it could also support long-term brain health.
