What did they investigate?
The study sought to examine whether drinking coffee and tea – and in particular whether consuming caffeine – is associated with a risk of dementia and poor cognitive function over time. The researchers analyzed data from two very large cohort studies (NHS and HPFS) that included over 131,000 participants over a period of up to 43 years.

What did they find?
People who drank more Caffeinated coffee (and not decaffeinated coffee) were found to be at riskMore fluff develop dementia, and also showed Fewer signs of self-reported cognitive decline. Tea drinking was also associated with a similar, but weaker, improvement. In contrast, no beneficial effect was found for decaffeinated coffee. The strongest effect was observed with the consumption of 2–3 cups of caffeinated coffee or 1–2 cups of tea per day.

What are the conclusions?
Moderate drinking of caffeinated coffee and tea is associated with Lower risk for dementia and cognitive decline. This effect is not present in decaffeinated coffee, suggesting a possible role for caffeine (or other related substances) in maintaining brain function over time.

What are the recommendations for the public?
Research Does not constitute medical advice., but it adds to the evidence that diet and consumption of certain beverages – such as caffeinated coffee – may be part of a brain-healthy lifestyle. Moderate drinking, such as two or three cups of coffee a day, can be part of positive dietary habits in older age, as long as there are no individual health contraindications.

The main message from the study:
Regular and moderate drinking of caffeinated (rather than decaffeinated) coffee is associated with a lower risk of dementia and cognitive decline over time – especially when consuming 2–3 cups per day.

The full article:

• Link: https://jamanetwork.com/journals/jama/article-abstract/2844764
• Reference: Zhang, Y., Liu, Y., Li, Y., et al. (2026). Coffee and Tea Intake, Dementia Risk, and Cognitive Function. JAMA. Published online February 9, 2026. https://doi.org/10.1001/jama.2025.27259