“This daily habit could lower dementia risk by 35%, scientists say” [Science Daily (original)]:
A large US study followed 131,821 nurses and healthcare professionals for as long as 43 years, beginning when participants were in their early 40s. Over the course of the study, 11,033 participants, about 8%, developed dementia. Researchers found that people who regularly consumed moderate amounts of caffeinated coffee or tea were less likely to develop the condition.
The strongest benefit appeared in adults age 75 and younger. In that group, consuming about 250mg-300mg of caffeine per day, equal to roughly two to three cups of coffee, was linked to a 35% lower dementia risk. Drinking more caffeine than that did not provide additional protection….
Why Caffeine May Help Protect the Brain
Scientists say there are several biological explanations for caffeine’s potential brain benefits. Caffeine blocks adenosine, a chemical that slows the activity of important brain messengers such as dopamine and acetylcholine. These neurotransmitters naturally become less active with age and in diseases like Alzheimer’s, so caffeine may help counteract that decline.
Caffeine may also support brain health by reducing inflammation and helping regulate blood sugar metabolism. Studies have shown that people who regularly drank more than two cups of coffee daily throughout their lives, but did not have dementia (yet?), had lower levels of amyloid plaques in the brain. These toxic plaques are commonly found in people with Alzheimer’s disease.
Coffee and tea contain other compounds beyond caffeine that may benefit the brain as well. Antioxidants and substances that support healthy blood vessels could also play a role in protecting the aging brain.
Why More Coffee Is Not Better
Researchers say there are several reasons why very high caffeine intake may stop being beneficial. One possibility is that the body processes caffeine differently at higher doses. Excessive caffeine can also interfere with sleep and increase anxiety, both of which may negatively affect brain health.
This idea fits with a psychological principle known as the Yerkes-Dodson law, first proposed in 1908. The law suggests that mental performance improves with stimulation only up to a point. Once stimulation becomes too high, whether from stress, anxiety, or too much caffeine, performance begins to decline.