Tea & Coffee Linked to Lower Dementia Risk – Study Finds

Regular consumption of caffeinated tea or coffee may be associated with a reduced risk of dementia and slower cognitive decline, according to a large, long-term study published in February 9, 2026, in the Journal of the American Medical Association (JAMA). The research, involving over 130,000 participants, suggests that moderate daily intake – two to three cups of coffee or one to two cups of tea – could offer some protection against neurodegenerative diseases.

Researchers analyzed data from the Nurses’ Health Study and the Health Professionals Follow-Up Study, tracking participants for an average of 43 years. The findings indicated that individuals with the highest intake of caffeinated coffee had an 18% lower risk of developing dementia compared to those with the lowest intake. Tea drinkers with the highest consumption showed a 16% reduced risk. Those who regularly consumed the most tea and coffee demonstrated a slower rate of cognitive decline.

However, the study authors emphasize that these findings do not establish a causal relationship. “Our study alone can’t prove causality, but to our knowledge, We see the best evidence to date looking at coffee and tea intake and cognitive health, and it is consistent with plausible biology,” explained Dr. Daniel Wang of Harvard Medical School, the study’s lead author. The research also found no association between decaffeinated coffee and a lower risk of dementia or improved cognitive function, suggesting that caffeine may be a key component in any potential protective effect.

The observed benefits were most pronounced at moderate consumption levels. Dr. Wang noted that the strongest associations were seen with approximately two to three cups per day of caffeinated coffee and one to two cups per day of caffeinated tea. This suggests that exceeding these amounts may not yield additional benefits and could potentially have adverse effects.

While the results are encouraging, experts caution against overinterpretation. Dr. Susan Kohlhaas of Alzheimer’s Research UK commented that the study “doesn’t prove that coffee or tea protect the brain.” Professor Tara Spires-Jones, at the UK Dementia Research Institute, echoed this sentiment, highlighting “important limitations” and suggesting that other factors related to coffee and tea-drinking habits could be responsible for the observed associations.

The potential mechanisms underlying these findings are still being investigated. Researchers hypothesize that bioactive ingredients in coffee and tea, such as caffeine and polyphenols, may play a role in reducing nerve cell inflammation and damage, thereby protecting against cognitive decline. However, further research is needed to validate these mechanisms and identify the specific compounds responsible for any protective effects.

It’s important to consider the possibility of “reverse causation,” as noted by Dr. Mohammad Talaei from Queen Mary University of London. This refers to the scenario where individuals in the early stages of cognitive decline may alter their caffeine intake, potentially reducing their consumption, which could create an illusion that caffeine lowers dementia risk when the opposite is true. Dietary substitutions – swapping coffee for other beverages, for example – could also complicate the interpretation of the findings.

The study also acknowledges that the effect size, even if causal, is relatively small. Professor Jules Griffin from the University of Aberdeen described the evidence as “compelling” but pointed out that “the reduction in risk is quite a small decrease.” Professor Naveed Sattar at the University of Glasgow advised interpreting the findings with “considerable caution,” characterizing them as “suggestive” only. Dr. Simon White at the University of Cambridge stressed that the study does not provide sufficient evidence to recommend changing people’s behaviors based on these results.

This research adds to a growing body of evidence suggesting that lifestyle factors play a significant role in dementia risk. Previous studies have consistently demonstrated that physical exercise, a healthy diet, and adequate sleep are all associated with lower dementia risk. While the findings regarding coffee and tea are promising, they should be viewed as one piece of a larger puzzle.

The researchers emphasize the need for further investigation to confirm these findings and to better understand the complex relationship between caffeine, tea, coffee, and cognitive health. For now, moderate consumption of caffeinated coffee or tea may be a reasonable addition to a brain-healthy lifestyle, but it should not be considered a guaranteed preventative measure against dementia.