Researchers from several leading U.S. institutions looked at health data from 131,821 adults who were part of the Nurses' Health Study and the Health Professionals Follow‑Up Study. They discovered that drinking moderate amounts of caffeinated coffee (about 2‑3 cups daily) or tea (about 1‑2 cups daily) was linked to a lower chance of developing dementia, slower loss of memory, and better overall thinking abilities. The results appeared in the journal JAMA.
Why Stopping Dementia Early Matters
Most medicines for dementia work only a little and are given after symptoms appear. Because of this, scientists are looking at everyday habits—like what we eat and drink—that might help keep the brain healthy before problems start.
Coffee and tea contain natural chemicals called polyphenols and caffeine. These compounds can lower inflammation and protect cells, both of which are important for brain health. Earlier studies gave mixed answers, often because they were short‑term or had small groups of people.
Long‑Term Study Gives Clearer Answers
The two big studies followed participants for up to 43 years. Researchers repeatedly recorded what people ate, whether they were diagnosed with dementia, how they felt about their own memory, and how they performed on memory tests. They then examined how drinking caffeinated coffee, tea, or decaf coffee related to brain health over many years.
Out of the more than 130,000 people, 11,033 later developed dementia. Those who drank more caffeinated coffee had an 18 % lower risk of dementia compared with people who rarely or never drank it. They also reported fewer memory worries (7.8 % vs. 9.5 %) and scored better on some memory tests.
Caffeine May Be the Key Ingredient
Tea drinkers showed a similar pattern, while people who chose decaf coffee did not see the same benefits. This suggests that caffeine—rather than other parts of the drink—could be helping the brain, though more research is needed to understand exactly how.
The strongest protection was seen in people who had 2‑3 cups of coffee or 1‑2 cups of tea each day. Drinking even more caffeine did not cause harm; the benefits stayed about the same as with moderate amounts.
Study Support
The work was funded by several National Institutes of Health grants. The funders did not influence how the study was designed, carried out, analyzed, written, or published.