Moderate consumption of caffeinated coffee or tea is associated with a lower risk of dementia and better cognitive function. This was the result of a large prospective cohort study with data from the Nurses’ Health Study (NHS) and the Health Professionals Follow-up Study (HPFS), which ran for up to 43 years.

The analysis included 131,821 participants (86,606 women from the NHS and 45,215 men from HPFS) who did not have dementia, Parkinson’s disease or cancer at baseline. Over the observation period (median 36.8 years), 11,033 people developed dementia.

The consumption of caffeinated coffee or tea was repeatedly recorded by questionnaire (1 cup = 237 ml). The participants were divided into quartiles. In the highest quartile, women drank an average of 4.5 cups per day, men 2.5 cups; in the lowest quartiles there was no consumption.

After adjusting for demographic factors, lifestyle, nutritional quality, comorbidities and other confounders, a significantly lower risk of dementia was found with higher consumption of caffeinated coffee (hazard ratio 0.82; 95% CI 0.76–0.89 in comparison highest vs. lowest quartile; 141 vs. 330 cases per 100,000 person-years). The prevalence of subjective cognitive impairment was also lower (7.8% vs. 9.5%; prevalence ratio 0.85; 95% CI 0.78–0.93). In the NHS cohort, higher coffee consumption was also associated with slightly better objective cognitive performance.

Similar effects were seen with caffeinated tea. Decaffeinated coffee or tea, on the other hand, had no protective relationship. A dose-response analysis revealed non-linear inverse associations; the strongest effect occurred with about 2–3 cups of caffeinated coffee or 1–2 cups of tea per day.

The German Society of Neurology (DGN) assesses the results as physiologically plausible. Possible mechanisms include a reduction of beta-amyloid deposits by caffeine, a reduction of neuroinflammatory processes, antioxidant effects of bioactive substances such as polyphenols and chlorogenic acid, and an improvement in insulin sensitivity. Nevertheless, these are observational data from a high-quality cohort study – not randomized controlled results. Causal conclusions are therefore not possible, the DGN emphasizes.

The study was published in the journal “JAMA”.

Original Paper:

Coffee and Tea Intake, Dementia Risk, and Cognitive Function | Lifestyle Behaviors | JAMA | JAMA Network

Editor: X-Press Journalistenbüro GbR

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