Moderate coffee or tea intake was linked with lower dementia risk and better cognitive performance.The greatest benefit was associated with 2-3 cups of caffeinated coffee or 1-2 cups of tea daily.Decaf coffee had no relationship with dementia risk or cognitive outcomes.
Moderate daily consumption of caffeinated coffee or tea was tied to reduced dementia risk and better cognitive function over time, a prospective study of health professionals showed.
Over a median follow-up of 36.8 years, health professionals in the highest quartile of coffee drinking had an 18% lower risk of dementia compared with those in the lowest quartile (HR 0.82, 95% CI 0.76-0.89, P<0.001), reported Dong Wang, MD, ScD, of Brigham and Women's Hospital in Boston, and colleagues.
Top coffee drinkers also showed a reduced prevalence of subjective cognitive decline (prevalence ratio 0.85, 95% CI 0.78-0.93, P<0.001) and modestly better cognitive performance, the researchers said in JAMA.
Approximately two to three cups of caffeinated coffee or one to two cups of tea a day were associated with the lowest risk of dementia, Wang and co-authors stated. Similar patterns emerged for subjective cognitive decline, “reinforcing the notion that a daily intake of two to three cups of caffeinated coffee (around 300 mg of caffeine) was associated with optimal cognition,” they wrote.
No additional advantages were seen with higher coffee intake. Decaffeinated coffee was not associated with lower dementia risk or better cognitive performance.
“While our results are encouraging, it’s important to remember that the effect size is small and there are lots of important ways to protect cognitive function as we age,” Wang said in a statement. “Our study suggests that caffeinated coffee or tea consumption can be one piece of that puzzle.”
This is not the first study to show relationships between coffee or tea and cognition, but it’s one of the largest and longest, with 131,821 participants from the Nurses’ Health Study (NHS) and Health Professionals Follow-Up Study (HPFS) and up to 43 years of follow-up.
In 2024, a study of 8,500 U.K. Biobank participants showed that moderate coffee intake predicted less fluid intelligence decline over 8.8 years; drinking four or more cups daily, however, offered no added benefit. High tea consumption, more common in the U.K., also was tied to better cognitive performance.
Both coffee and tea contain bioactive compounds, including polyphenols and caffeine. Coffee has been associated with lower risks of cardiovascular disease mortality and all-cause mortality. Caffeine also may play a protective role in Parkinson’s disease.
Wang and colleagues followed 86,606 women in the NHS from 1980-2023 and 45,215 men in the HPFS from 1986-2023, all of whom did not have cancer, Parkinson’s disease, or dementia at baseline. Participants filled out food frequency questionnaires every 2 to 4 years.
Mean baseline age was 46.2 years in the NHS and 53.8 years in the HPFS. Over the follow-up period, 11,033 participants had a dementia diagnosis, identified by death records and physician diagnoses.
Secondary outcomes included subjective cognitive decline, assessed by a questionnaire. Objective cognitive function was evaluated in the NHS only, using the Telephone Interview for Cognitive Status (TICS) tool and a global cognition measure that was a mean z score of six cognitive tests.
In the NHS, top coffee and tea drinkers had higher mean TICS scores versus the lowest quartile, but the effect was modest, the researchers noted. Associations between coffee intake and global cognition z scores were not significant.
Results did not significantly differ across subgroups based on body mass index, smoking status, APOE4 genotype, or Alzheimer’s disease polygenic risk scores. Associations between caffeine intake and dementia risk were consistent in a 4-year lag analysis.
The study’s limitations included potential residual confounding and a lack of detail about tea type or coffee preparation, which may affect caffeine and bioactive compound concentrations. Each cohort included single-sex health professionals, which may limit generalizability to broader populations, the researchers acknowledged.
