Drinking a few cups of caffeinated coffee or tea daily may modestly help preserve brain function and reduce the risk of dementia, researchers said.
The study, published in JAMA, found that people with the highest daily intake of caffeinated coffee had an 18% lower risk of developing dementia compared to those with the lowest intake.
They also reported nearly 2 percentage points fewer self-perceived memory or thinking problems. Similar results were observed for caffeinated tea, but not for decaffeinated beverages.
The research was based on questionnaires from 132,000 U.S. adults over four decades. Participants who drank two to three cups of caffeinated coffee or one to two cups of caffeinated tea daily showed the most pronounced benefits. Some objective tests also showed better cognitive performance among regular coffee drinkers.
However, study leader Dr. Daniel Wang of Harvard Medical School emphasized that the study does not prove caffeine protects the brain and that the effect, if any, is small.
“Lifestyle factors linked with lower dementia risk include physical exercise, a healthy diet, and adequate sleep. Our study suggests that caffeinated coffee or tea consumption can be one piece of that puzzle,” Wang said.
The researchers noted that bioactive compounds in coffee and tea, including caffeine and polyphenols, may help reduce nerve cell inflammation and damage, offering some protection against cognitive decline. The effects were similar regardless of genetic predisposition to dementia, according to coauthor Dr. Yu Zhang of the Harvard T.H. Chan School of Public Health.
Further research is needed to confirm the mechanisms behind these findings.
