Coffee & Tea Linked to Lower Dementia Risk: New Study

Habitual consumption of coffee or tea – roughly two to three cups of caffeinated coffee or one to two cups of caffeinated tea daily – may be associated with a reduced risk of dementia and slower cognitive decline, according to new research published February 9, 2026 in the Journal of the American Medical Association. The findings, based on analysis of health records spanning over four decades, suggest a potential link between moderate caffeine intake and brain health, though researchers emphasize that correlation does not equal causation.

The study, led by Yu Zhang of Harvard University, analyzed data from 131,821 participants enrolled in two long-term US public health studies: the Nurses’ Health Study and the Health Professionals Follow-up Study. Researchers tracked participants’ dietary habits, dementia diagnoses, cognitive performance, and other health metrics for up to 43 years. The analysis revealed that individuals who consistently consumed moderate amounts of caffeinated coffee had an 18% lower risk of dementia compared to those who rarely or never drank it. Similar results were observed for tea consumption.

“Our study alone can’t prove causality, but to our knowledge, This proves the best evidence to date looking at coffee and tea intake and cognitive health, and it is consistent with plausible biology,” said Zhang.

Interestingly, the observed benefits were not replicated with decaffeinated coffee. This suggests that caffeine, rather than other compounds present in coffee, may be the primary driver of the neuroprotective effects. However, researchers caution against interpreting this as a green light to drastically increase caffeine consumption.

The potential mechanisms behind this association are still being investigated. Coffee and tea contain both caffeine and polyphenols, compounds known for their antioxidant and anti-inflammatory properties. These properties may help protect against brain aging by improving vascular health, reducing inflammation, and mitigating oxidative stress – a process where harmful molecules damage cells. Caffeine has also been linked to a lower risk of type 2 diabetes, a known risk factor for dementia.

The study also noted that caffeinated coffee drinkers reported slightly less cognitive decline over time and performed better on certain tests of brain function compared to those who opted for decaf. The effect appeared to plateau at two to three cups of caffeinated coffee or one to two cups of caffeinated tea per day, suggesting that exceeding these amounts did not confer additional benefits.

While the findings are encouraging, experts emphasize the need for further research to confirm a causal relationship. Conducting randomized controlled trials – where participants are randomly assigned to drink caffeinated or decaffeinated beverages for decades – would be the gold standard for establishing causality, but such trials are largely impractical. Researchers are now exploring whether coffee and tea consumption leads to measurable biological changes in the brain, such as alterations in brain scans or other biomarkers.

Naveed Sattar, a professor of cardiometabolic medicine at the University of Glasgow, highlighted the complexity of caffeine’s effects on the brain. “Caffeine does a multitude of things, some which may be beneficial, some which may be harmful, and the net effect can never be estimated until you do a randomised trial,” he explained.

It’s also important to consider that caffeine can have varying effects on individuals, and factors such as genetics, overall health, and lifestyle can influence its impact. For some, caffeine can raise blood pressure, a significant risk factor for dementia.

Researchers estimate that approximately half of dementia cases worldwide could be prevented or delayed by addressing modifiable risk factors such as obesity, smoking, excessive alcohol consumption, hearing loss, and high blood pressure. Maintaining a healthy lifestyle, including regular exercise, a balanced diet, and sufficient sleep, remains paramount for brain health.

“Don’t think of coffee or tea as a magic shield,” Zhang cautioned. “I’d say maintaining a healthy lifestyle, getting regular exercise, having a balanced diet and getting good sleep are all important to get better brain health.”

This research adds to a growing body of evidence suggesting that dietary factors may play a role in dementia prevention. While more research is needed to fully understand the relationship between coffee, tea, and cognitive health, the current findings offer a reassuring message for those who enjoy these beverages in moderation.