A new study seems almost too good to be true: Drinking coffee may help prevent dementia. As a coffee drinker myself, I was initially skeptical of the claim. It seemed to be yet another instance of a paper hyping up a “superfood” to validate a habit that many of us already have. After all, almost half of Americans drink coffee daily.
But this study, funded by the National Institutes of Health and published in JAMA, was unusually convincing. The researchers analyzed data from more than 131,000 people over multiple decades. Every two to four years, participants completed detailed questionnaires about their diet, including coffee and tea consumption. Investigators tracked dementia diagnoses, cognitive testing results and self-reported problems with thinking and memory, with follow-ups extending up to 43 years.
During the study period, roughly 11,000 participants developed dementia. Those who regularly drank caffeinated coffee had an 18 percent lower risk compared to people who drank little or none. Regular coffee drinkers also performed better on some cognitive tests and were less likely to report mental decline.
Interestingly, people who drank higher amounts of caffeinated tea experienced similar cognitive benefits, whereas those who consumed decaffeinated coffee did not. Caffeine’s apparent benefits remained even after accounting for factors such as genetic risk for Alzheimer’s disease, smoking, obesity, overall diet quality and socioeconomic status.
This study adds to a growing body of research suggesting that caffeine may support brain health. Exactly how it does this is not fully understood. Scientists have proposed several possible mechanisms, including reducing inflammatory chemicals and improving blood sugar control, since both chronic inflammation and diabetes are linked to a higher risk of cognitive decline.
The existence of a biological basis is reinforced by another finding in the study: There appears to be an optimal range of coffee consumption beyond which no additional cognitive benefit was observed: two to three eight-ounce cups per day, or roughly 300 milligrams of caffeine. This plateau is physiologically plausible, as the body can only metabolize so much caffeine before its receptors become saturated.
It is also possible that caffeine itself is not the primary driver but rather what it enables. A morning cup of coffee may make someone more alert and mentally active. Perhaps coffee drinkers are more inclined to tackle a crossword puzzle, read the newspaper or join a book club, all activities that could support cognitive health. In that case, caffeine may be less a direct neuroprotective agent and more a catalyst for behaviors that keep the brain engaged. If a daily cup nudges people toward greater mental stimulation and social interaction, that too would be a meaningful benefit.
This does not mean everyone should drink caffeine. Children especially should not. The American Academy of Pediatrics has cautioned against young people consuming energy drinks, sodas and other caffeinated beverages because caffeine can disrupt sleep and worsen anxiety and hyperactivity. People with heart rhythm disorders, uncontrolled high blood pressure or certain thyroid conditions may experience adverse effects from caffeine and should speak with their physician about what amount, if any, is appropriate.
For most adults, up to about 400 milligrams of caffeine per day is considered safe. As with many dietary habits, portion size matters. A single large “venti” Starbucks coffee can contain that entire amount. People who are sensitive to caffeine should moderate their intake and avoid drinking it later in the day so that it does not interfere with sleep.
Moreover, pay attention to what goes into the cup. A 2025 study found that people who drank at least one cup of coffee daily had about a 14 percent lower risk of premature death. The benefit, however, was seen primarily among those who drank black coffee or coffee with minimal added sugar and saturated fat. Loading coffee with sugar and cream may offset potential advantages by increasing risks such as diabetes and heart disease.
Skeptics are right to caution that these studies are not definitive. We already know that regular exercise, a healthy diet, good sleep and social engagement are powerful contributors to brain health. Coffee is hardly a substitute for those foundations.
But imagine the excitement that a new medication would generate if it were shown to reduce dementia risk by 18 percent. The point is not that coffee is a miracle cure but that if something as simple and widely enjoyed as moderate coffee consumption may offer a neuroprotective benefit, it is reasonable to consider it as part of a broader preventive health strategy. We should welcome more research like this that gives people practical, evidence-informed ways to actively protect their health and stay mentally sharp.
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