For many, a morning cup of coffee is a non-negotiable ritual to jumpstart the day. Now, a massive, decades-long study suggests that your caffeine habit might be doing more than just waking you up, it could be shielding your brain from dementia.
The research, published Monday in JAMA, tracked more than 130,000 health professionals for up to 43 years. The findings offer some of the most robust evidence to date that moderate consumption of caffeinated coffee and tea is linked to a significantly lower risk of cognitive decline.
The Power of the Long Game
Unlike previous studies that looked at coffee habits over short periods, this research, led by investigators from Massachusetts General Hospital and Harvard utilized data from the Nurses’ Health Study and the Health Professionals Follow-up Study.
By following 131,821 participants from the 1980s through 2023, researchers were able to document 11,033 cases of dementia. Because the participants reported their diet every two to four years using validated questionnaires, the study provides a rare look at how lifelong habits impact the aging brain.
Caffeine vs. Decaf: A Clear Winner
One of the study’s most significant takeaways is the distinction between caffeinated and decaffeinated beverages.
Participants in the highest quartile of caffeinated coffee consumption had an 18% lower risk of dementia compared to those in the lowest quartile. They also reported lower rates of “subjective cognitive decline”—the self-perceived “brain fog” or memory lapses that often precede a formal diagnosis.
However, those who reached for decaf didn’t see the same benefits. The study found no significant association between decaffeinated coffee and a reduced risk of dementia, suggesting that the caffeine itself, or compounds specifically linked to the caffeinated bean, may be the key protective element.
The “Sweet Spot” for Your Daily Dose
If you’re looking to optimize your brain health, more isn’t necessarily better. The researchers found a “nonlinear” relationship, meaning the benefits peaked at moderate levels.
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Caffeinated Coffee: The most pronounced reduction in risk was seen in people drinking approximately 2 to 3 cups per day.
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Tea: For tea drinkers, the “sweet spot” was lower, at about 1 to 2 cups per day.
“Greater consumption of caffeinated coffee and tea was associated with lower risk of dementia and modestly better cognitive function,” the study authors concluded, noting that the most significant associations appeared at these moderate intake levels.
Beyond Memory Loss
The researchers didn’t just look at dementia diagnoses; they also tested objective cognitive function. In a subset of female participants who underwent telephone-based neuropsychological tests, those with higher caffeinated coffee intake performed better on memory and thinking tasks (the Telephone Interview for Cognitive Status, or TICS).
While the study is observational ,meaning it cannot prove that coffee causes a lower risk, only that the two are linked the sheer scale and duration of the follow-up make it one of the most compelling arguments for the beverage’s neuroprotective properties.
What This Means for You
For the millions of Americans who already drink coffee, the news is a reassuring “green light.”
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