Adults who drink two to three cups of caffeinated coffee daily develop dementia at a rate of 141 cases per 100,000 people annually, compared to 330 cases for those who rarely or never consume the beverage, according to a long-term study published in JAMA.
The investigation followed 131,821 participants, including approximately 87,000 female nurses and 45,000 male healthcare workers, for up to 43 years. Researchers from Harvard T.H. Chan School of Public Health, Brigham and Women’s Hospital, and Harvard Medical School analyzed dietary questionnaires administered every two to four years between 1980 and 2023 for women and between 1986 and 2023 for men. During a median follow-up of 36.8 years, the team documented 11,033 cases of dementia.
High Coffee Consumption Lowers Dementia Risk
Participants in the highest consumption group showed an estimated 18 percent lower relative risk of dementia compared to those in the lowest intake group, with a hazard ratio of 0.82 and a 95 percent confidence interval ranging from 0.76 to 0.89, as reported by Comunicaffe. Self-reported subjective cognitive decline—such as worsening memory or thinking noticed by the individual—was also lower among high consumers, appearing in 7.8 percent of that group compared to 9.5 percent in the lowest intake group.
The benefits extended across participants regardless of their genetic risk of developing dementia. Individuals carrying inherited DNA variations associated with higher vulnerability showed the same general pattern. Decaffeinated coffee, however, showed no statistically significant association with dementia risk, prompting researchers to examine whether caffeine itself contributes to the observed connection.
Moderate Tea Drinking Improves Cognitive Functioning
Tea drinking was also linked to lower dementia risk and better cognitive functioning, with the strongest associations appearing among participants consuming one to two cups per day. Because the study did not distinguish between caffeinated and noncaffeinated tea, researchers could not determine whether caffeine played a specific role in the tea findings, according to The Dingo Daily.
Exceeding moderate consumption levels provided no additional protection. Drinking four or more cups of coffee daily did not yield further benefits, and medical specialists recommend consuming the beverage during the first half of the day. Aleksey Utin, a cardiologist and cardiovascular surgeon cited by Rambler, explained that evening caffeine intake can disrupt sleep quality and shorten deep sleep phases. Because the brain’s lymphatic waste-clearance system operates actively during deep sleep, chronic sleep disruption from late-day coffee could theoretically impair cognitive functions over time.
Does Drinking Coffee Directly Prevent Dementia?
Does drinking coffee directly prevent dementia? No. The investigation is an observational study that establishes a correlation rather than a direct cause-and-effect relationship, meaning other lifestyle factors could influence the results.
Does drinking more coffee increase the protection? No. The most favorable outcomes clustered around two to three cups per day, and pushing past that range bought no extra benefit.
Are lifestyle factors more influential than coffee? Yes. Medical specialists emphasize that blood pressure control, lipid and blood sugar management, physical activity, consistent sleep, social engagement, and continuous learning exert a much stronger influence on long-term brain health.