A long-running study of U.S. adults found that people who drank two to three cups of caffeinated coffee daily showed substantially lower dementia rates than those who rarely or never drank coffee. Researchers recorded 141 dementia cases annually per 100,000 regular caffeinated coffee drinkers, compared with 330 cases per 100,000 among non-drinkers. Follow-up periods extended as long as 43 years.
Adults who consumed higher amounts of caffeinated coffee were also less likely to report subjective cognitive decline. Among high coffee consumers, 7.8% reported memory or thinking problems compared with 9.5% of those who rarely drank coffee.
Tea consumption showed similar benefits, with the strongest associations appearing among people who drank one to two cups daily. Decaffeinated coffee did not show the same benefits as regular coffee, suggesting caffeine may play a role, though researchers noted this does not prove caffeine causes the protection.
The association with lower dementia risk remained apparent regardless of participants' genetic risk factors. The study found no additional benefit from consuming coffee beyond the two to three cup range.
Researchers emphasized the results show an association rather than proving coffee directly prevents dementia. Other differences between coffee drinkers and non-drinkers could contribute to the observed outcomes. The American Physiological Society provided the findings, with original reporting by Tori DeAngelis.