Your Daily Cup of Coffee Could Reduce Your Risk of Dementia by 35 Percent

Scientists say that your daily coffee routine might do more than just give you a boost of energy. New research suggests that drinking a moderate amount of caffeinated coffee or tea could help lower the risk of dementia in old age. However, the positive effects seem to diminish after a certain point, meaning that more caffeine isn’t necessarily better for the brain.

Caffeine and a Lower Risk of Dementia

A large-scale U.S. study followed 131,821 nurses and healthcare professionals for up to 43 years, beginning when the participants were in their early 40s. Over the course of the study, 11,033 participants, about 8%, developed dementia. The researchers found that people who regularly consumed moderate amounts of caffeinated coffee or tea were less likely to develop the condition. The strongest positive effect was seen in adults aged 75 and younger. In this group, consuming about 250 to 300 mg of caffeine per day—which is roughly equivalent to two to three cups of coffee—was associated with a 35% lower risk of dementia. Higher caffeine intake did not provide additional protection.

At the start of the study, the women reported drinking an average of about four and a half cups of coffee or tea daily, while the men drank an average of about two and a half cups. Participants who consumed more caffeinated coffee were often younger, but they also tended to drink more alcohol, smoke more, and consume more calories—all factors associated with a higher risk of dementia. The researchers also observed an unexpected trend regarding decaffeinated coffee. People who drank more decaffeinated coffee exhibited faster memory loss. The researchers suspect this may be because some people switched to decaffeinated coffee after developing sleep disorders, high blood pressure, or heart rhythm disorders—conditions that are themselves linked to cognitive decline and dementia.

Why Caffeine Might Help Protect the Brain

Scientists say there are several biological explanations for the potential benefits of caffeine for the brain. Caffeine blocks adenosine, a chemical that slows down the activity of key brain messengers such as dopamine and acetylcholine. These neurotransmitters naturally become less active with age and in conditions like Alzheimer’s, so caffeine may counteract this decline. Caffeine may also support brain health by reducing inflammation and regulating blood sugar metabolism. Studies have shown that people who regularly drank more than two cups of coffee a day throughout their lives but did not (yet?) suffer from dementia had lower levels of amyloid plaques in the brain. These toxic plaques are commonly found in people with Alzheimer’s disease.

In addition to caffeine, coffee and tea contain other compounds that may also have a positive effect on the brain. Antioxidants and substances that support healthy blood vessels may also play a role in protecting the aging brain. The study found that one to two cups of tea per day offered the strongest protection against dementia. The researchers noted that tea consumption in the U.S. is generally lower than coffee consumption, which could influence the results. Green tea was not examined separately, although many previous studies suggest that it, too, could help reduce the risk of dementia.

Why More Coffee isn’t Better

Researchers say there are several reasons why very high caffeine intake might lose its positive effect. One possibility is that the body processes caffeine differently at higher doses. Excessive caffeine can also disrupt sleep and increase anxiety, both of which can negatively impact brain health.

This idea aligns with a psychological principle known as Yerkes-Dodson’s Law, first proposed in 1908. The law states that mental performance improves through stimulation only up to a certain point. Once stimulation becomes too high—whether due to stress, anxiety, or too much caffeine—performance begins to decline. Although the study focused on healthcare professionals, the researchers found similar patterns when they analyzed the results of 38 additional studies. In these studies, caffeine consumers had a 6% to 16% lower risk of dementia compared to non-consumers, with one to three cups of coffee appearing to offer the greatest benefit. Tea drinkers also showed promising results, with higher tea consumption associated with stronger protection.

Moderate Caffeine Consumption May be Ideal

Moderate caffeine consumption does not appear to increase long-term blood pressure risk and may even lower the risk of cardiovascular disease, which shares many risk factors with dementia. Nevertheless, experts advise people with very high blood pressure to limit themselves to about one cup of coffee per day.

The researchers also caution that measuring caffeine intake in “cups” is not accurate. Caffeine content can vary widely depending on how the coffee is prepared. Freshly brewed coffee made from whole beans can have very different caffeine levels compared to instant coffee, and preparation methods can also affect cholesterol levels.

Even relatively small amounts of caffeine can have noticeable effects. Studies show that doses as low as 40 to 60 mg can improve mood and attention in middle-aged adults who normally consume little or no caffeine. The findings suggest that moderation may be key when it comes to coffee and brain health.