2–3 cups of coffee a day may reduce the risk of dementia – but there's an important condition

A large, long-term study has shown that moderate consumption of caffeinated coffee and tea is associated with a lower risk of developing dementia, writes The New York Times.

Researchers analyzed data from 131,821 people who were followed for up to 43 years. The results were published in the journal JAMA, indicate that 2–3 cups of coffee a day or 1–2 cups of caffeinated tea are associated with a reduced risk of dementia compared to those who consumed almost no caffeine.

An important clarification: decaffeinated beverages did not have this effect.

According to epidemiologist Daniel Wang of Mass General Brigham, the benefits of coffee "plateau" after about 2.5 cups a day. The likely reason is that the body has limitations on the metabolism of bioactive substances found in coffee and tea.

Study participants who regularly consumed caffeine had an approximately 20% lower risk of dementia if they drank coffee, and a 15% lower risk if they consumed tea daily.

This association persisted regardless of genetic predisposition to Alzheimer's disease, education level, socioeconomic status, diet, smoking, BMI, or mental health.

Separately, researchers assessed so-called subjective cognitive decline – the feeling that memory and thinking are deteriorating. It was less frequently recorded among those who consumed more caffeine.

Scientists suggest that caffeine can reduce neuroinflammation, improve vascular function, and increase insulin sensitivity (and diabetes is a known risk factor for dementia).

At the same time, the authors emphasize that this is a correlation, not direct evidence of a cause-and-effect relationship. For those who don't drink coffee at all, this is not a recommendation to start. But for those who do, it's another argument that moderation can work in favor of the brain.