That daily cup of coffee or tea might do more than wake you up. It could help protect your brain over the long term.
A new study found that drinking a moderate amount of caffeinated coffee or tea was linked to an 18% lower risk of dementia. It also led to better thinking skills over time. The best benefits came from two to three cups of coffee or one to two cups of tea daily. These benefits even showed up in people who were more likely to get dementia due to their genes.
Why Preventing Dementia Matters
Preventing dementia early is very important. Current treatments offer only small benefits once symptoms start. Because of this, scientists are looking at lifestyle factors, like diet, that might affect brain health.
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Start Your News DetoxCoffee and tea have compounds like polyphenols and caffeine. These are thought to support brain health. They may help reduce inflammation and cell damage, which are both linked to thinking problems. Past research on coffee and dementia has had mixed results. This was often due to shorter study times or less data on long-term drinking habits.
Long-Term Study Offers Clearer Answers
Researchers from Mass General Brigham, Harvard T.H. Chan School of Public Health, and the Broad Institute of MIT and Harvard looked at data from 131,821 people. These participants were part of the Nurses' Health Study (NHS) and Health Professionals Follow-Up Study (HPFS).
The study tracked people for up to 43 years. They regularly checked diet, dementia diagnoses, memory concerns, and thinking abilities. The researchers studied how drinking caffeinated coffee, tea, and decaffeinated coffee related to long-term brain health.
Out of more than 130,000 participants, 11,033 developed dementia. People who drank more caffeinated coffee had an 18% lower risk of dementia. They also reported fewer memory problems and did better on certain thinking tests.
Caffeine May Be Key
Similar results were seen for tea drinkers. However, decaffeinated coffee did not show the same benefits. This suggests that caffeine might be a key factor in these brain benefits. More research is needed to understand exactly how it works.
The strongest effects were seen in people who drank two to three cups of caffeinated coffee or one to two cups of tea each day. Drinking more caffeine did not seem to cause harm. It showed similar benefits to moderate intake.
"We also compared people with different genetic predispositions to developing dementia and saw the same results," said lead author Yu Zhang. "This means coffee or caffeine is likely equally beneficial for people with high and low genetic risk of developing dementia."
Daniel Wang, a senior author, noted that while the results are encouraging, the effect is small. He added that there are many important ways to protect thinking skills as we age. "Our study suggests that caffeinated coffee or tea consumption can be one piece of that puzzle," he said.
Deep Dive & References
Coffee and Tea Intake, Dementia Risk, and Cognitive Function - JAMA, 2026
