43-Year Study Links Coffee to Lower Risk of Dementia

A scientific study that followed over 130,000 people for up to 43 years investigated the relationship between coffee consumption and the risk of dementia. The results indicated that people who regularly drank caffeinated coffee had a lower risk of developing dementia and a lower perception of memory decline. Moderate consumption, around two to three cups a day, showed the strongest association. Decaffeinated coffee did not show the same effect. Although the results are promising, researchers emphasize that more studies are needed to confirm whether coffee really helps protect the brain.

Many people start their day with a cup of coffee, but this beverage may do more than just help wake you up. A long-term scientific study investigated whether coffee consumption is related to brain health and the risk of developing dementia.

The research followed over 130,000 people for several decades and found an interesting association between the consumption of caffeinated coffee and a lower risk of cognitive problems.

Dementia is a set of conditions that affect memory, reasoning, and other mental abilities. It occurs when brain cells begin to deteriorate or die, impairing the ability to think and remember. Among the best-known causes are diseases such as Alzheimer's. As the number of elderly people is increasing worldwide, understanding the factors that can protect the brain has become a priority for science.

To investigate this question, researchers used a type of research called a prospective cohort study. In this type of study, a large group of people is followed over many years to observe how their lifestyle habits may influence their health.

In this case, the scientists analyzed data from two large American studies involving healthcare professionals. In total, more than one hundred and thirty thousand adults who did not have dementia at the beginning of the research participated.

Over up to forty-three years, participants regularly answered detailed questionnaires about their diet, including the amount of coffee, decaffeinated coffee, and tea consumed.

These questionnaires are common tools in nutrition research and are carefully validated to ensure they provide reliable estimates of dietary habits. During the follow-up, scientists also recorded medical diagnoses and causes of death to identify new cases of dementia.

Furthermore, some participants underwent cognitive tests, which are assessments used to measure skills such as memory, attention, and reasoning. For some participants, these tests were conducted by telephone using a standardized method that allows for a simple and comparable assessment of mental state. Researchers also asked if people perceived changes in their memory or ability to concentrate over time.

The results showed that people who consumed more caffeinated coffee had a lower risk of developing dementia compared to those who drank little or no coffee.

They also showed a lower likelihood of reporting decline in memory or thinking. In some cognitive tests, average performance was also slightly better among more frequent coffee drinkers.

Interestingly, the same effect was not observed with decaffeinated coffee. This suggests that caffeine or other substances present in regular coffee may be related to this possible benefit. Tea, which also contains caffeine and antioxidant compounds, showed similar associations, although the effect was more evident at moderate levels of consumption.

Researchers observed that the strongest benefit appeared among people who consumed about two to three cups of coffee per day or one to two cups of tea per day. Much larger amounts did not show clear additional advantages.

Still, the scientists emphasize that the study shows only an association, not definitive proof of cause and effect. Other lifestyle factors may also contribute to brain health.

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Coffee and Tea Intake, Dementia Risk, and Cognitive Function

Yu Zhang, Yuxi Liu, Yanping Li, Yuhan Li, Xiao Gu, Jae H. Kang, A. Heather Eliassen, Molin Wang, Eric B. Rimm, Walter C. Willett, Frank B. Hu, Meir J. Stampfer, and Dong D. Wang

JAMA. 9 February 2026

DOI: 10.1001/jama.2025.27259

Abstract:

Evidence linking coffee and tea to cognitive health remains inconclusive, and most studies fail to differentiate caffeinated from decaffeinated coffee. To investigate associations of coffee and tea intake with dementia risk and cognitive function. Prospective cohort study that included female participants from the Nurses’ Health Study (NHS; n = 86 606 with data from 1980-2023) and male participants from the Health Professionals Follow-up Study (HPFS; n = 45 215 with data from 1986-2023) who did not have cancer, Parkinson disease, or dementia at study entry (baseline) in the US. The primary exposures were intakes of caffeinated coffee, decaffeinated coffee, and tea. Dietary intake was collected every 2 to 4 years using validated food frequency questionnaires. The primary outcome was dementia, which was identified via death records and physician diagnoses. The secondary outcomes included subjective cognitive decline assessed by a questionnaire-based score (range, 0-7; higher scores indicate greater perceived decline; cases defined as those with a score ≥3) and objective cognitive function assessed only in the NHS cohort using telephone-based neuropsychological tests such as the Telephone Interview for Cognitive Status (TICS) score (range, 0-41) and a measure of global cognition (a standardized mean z score for all 6 administered cognitive tests). Among 131 821 participants (mean age at baseline, 46.2 [SD, 7.2] years in the NHS cohort and 53.8 [SD, 9.7] years in the HPFS cohort; 65.7% were female) during up to 43 years of follow-up (median, 36.8 years; IQR, 28-42 years), there were 11 033 cases of incident dementia. After adjusting for potential confounders and pooling results across cohorts, higher caffeinated coffee intake was significantly associated with lower dementia risk (141 vs 330 cases per 100 000 person-years comparing the fourth [highest] quartile of consumption with the first [lowest] quartile; hazard ratio, 0.82 [95% CI, 0.76 to 0.89]) and lower prevalence of subjective cognitive decline (7.8% vs 9.5%, respectively; prevalence ratio, 0.85 [95% CI, 0.78 to 0.93]). In the NHS cohort, higher caffeinated coffee intake was also associated with better objective cognitive performance. Compared with participants in the lowest quartile, those in the highest quartile had a higher mean TICS score (mean difference, 0.11 [95% CI, 0.01 to 0.21]) and a higher mean global cognition score (mean difference, 0.02 [95% CI, −0.01 to 0.04]); however, the association with global cognition was not statistically significant (P = .06). Higher intake of tea showed similar associations with these cognitive outcomes, whereas decaffeinated coffee intake was not associated with lower dementia risk or better cognitive performance. A dose-response analysis showed nonlinear inverse associations of caffeinated coffee and tea intake levels with dementia risk and subjective cognitive decline. The most pronounced associated differences were observed with intake of approximately 2 to 3 cups per day of caffeinated coffee or 1 to 2 cups per day of tea. Greater consumption of caffeinated coffee and tea was associated with lower risk of dementia and modestly better cognitive function, with the most pronounced association at moderate intake levels.