Coffee Cuts Dementia Risk: 2-3 Cups Daily Shows Strongest Protection

Moderate consumption of caffeinated coffee or tea may slow cognitive decline and reduce dementia risk, according to new research. The protective effects were most pronounced among those drinking 2-3 cups of caffeinated coffee or 1-2 cups of tea daily.

A research team led by Professor Daniel Wang at Harvard Medical School published findings in the Journal of the American Medical Association (JAMA) on the 10th (local time), analyzing data from approximately 130,000 participants in the Nurses' Health Study (NHS) and Health Professionals Follow-up Study (HPFS) over up to 43 years.

Participants completed food frequency questionnaires every 2-4 years. Researchers compared coffee and tea consumption against dementia diagnosis rates and changes in subjective and objective cognitive function.

The analysis found dementia incidence of 141 cases per 100,000 person-years among the top 25% of caffeine consumers, approximately 18% lower than the 330 cases in the bottom quartile. Caffeinated coffee drinkers also reported lower rates of subjective cognitive decline and performed better on certain cognitive tests.

Similar trends emerged among heavy tea drinkers. However, decaffeinated coffee showed no clear association with reduced dementia risk. The researchers interpreted this as evidence that caffeine is likely the key factor in cognitive protection.

Cognitive benefits were clearest at moderate intake levels. Effects peaked at 2-3 cups of coffee and 1-2 cups of tea daily. At these consumption levels, cardiovascular side effects and other risk signals raised in previous studies were not observed.

The research team explained that bioactive compounds in coffee and tea, including caffeine and polyphenols, may reduce inflammatory responses and inhibit neuronal damage.

However, as an observational study, the research cannot establish a causal relationship between caffeine consumption and dementia prevention. Professor Wang stated, "This suggests that caffeinated beverage consumption may be one of several factors that help protect cognitive health."