A large, decades-long study involving over 130,000 participants has investigated the link between coffee and tea consumption and the risk of developing dementia. The findings, published in February 2026, suggest a potential benefit to moderate intake of these widely consumed beverages.
The optimal amount – researchers identified a maximum limit.
The theory: A common factor among the drinks
A Swedish researcher: It’s fairly unlikely to be a coincidence.
Maintaining cognitive health is a growing public health concern as populations age, and lifestyle factors are increasingly recognized as playing a significant role. New research suggests that regular consumption of coffee and tea may offer some protection against cognitive decline and dementia.
The study, conducted by researchers at Harvard University and published on February 17, 2026, analyzed data from two long-term studies: the Nurses’ Health Study, which included 86,606 nurses, and the Health Professionals Follow-up Study, involving 45,215 male health professionals. A total of 131,821 participants were followed for up to 43 years, with an average follow-up period of 37 years.
Participants reported their coffee and tea intake regularly, categorizing it as “never,” “moderate” (1-3 cups per day), or “high” (4 or more cups per day). Throughout the study, 11,000 participants developed dementia, as identified through death records and self-reported medical diagnoses.
The findings revealed that individuals who consumed 2-3 cups of caffeinated coffee daily had an approximately 18% lower risk of developing dementia compared to those who did not drink coffee (hazard ratio (HR), 0.82; 95% confidence interval 0.76-0.89). Similarly, drinking 1-2 cups of tea per day was associated with a roughly 16% reduced risk of dementia (HR 0.86; 95% confidence interval 0.83-0.90). Notably, no association was found between decaffeinated coffee consumption and dementia risk.
A separate study, published in the Journal of Alzheimer’s Disease in 2025, similarly indicated a benefit. Researchers found that moderate coffee and tea consumption—defined as 1-3 cups daily—was associated with slower fluid intelligence decline and a slower increase in errors on cognitive tests. Specifically, those who never consumed coffee and those who were moderate coffee consumers showed slower cognitive decline compared to high consumers. The study followed over 8,700 dementia-free adults aged 60 to 85 for an average of 9.11 years.
According to the National Videnscenter for Demens, several population studies suggest an association between coffee and tea intake and a reduced risk of cognitive impairment later in life. However, the results regarding the connection between tea and coffee and dementia or mild cognitive impairment are mixed.
A Swedish researcher commented that the findings are “fairly unlikely to be a coincidence,” suggesting a potential underlying mechanism. While the exact reasons for this association remain unclear, researchers believe the neuroprotective effects of coffee and tea may be linked to their anti-inflammatory and antioxidant properties. Further research, including randomized controlled trials, is needed to establish a causal relationship and provide evidence-based recommendations.
