A large, decades-long study of more than 130,000 participants suggests that moderate consumption of caffeinated coffee or tea may support long-term cognitive health.
Researchers from Mass General Brigham, Harvard T.H. Chan School of Public Health, and the Broad Institute of MIT and Harvard conducted a large prospective cohort study involving 131,821 participants from the Nurses’ Health Study (NHS) and the Health Professionals Follow-Up Study (HPFS). The analysis found that moderate intake of caffeinated coffee (2-3 cups a day) or tea (1-2 cups a day) was linked to a lower risk of dementia, slower cognitive decline, and better preservation of cognitive abilities. The findings were published in JAMA.
“When searching for possible dementia prevention tools, we thought something as prevalent as coffee may be a promising dietary intervention—and our unique access to high quality data through studies that has been going on for more than 40 years allowed us to follow through on that idea,” said senior author Daniel Wang, MD, ScD, associate scientist with the Channing Division of Network Medicine in the Mass General Brigham Department of Medicine and assistant professor at Harvard Medical School. Wang is also an assistant professor in the Department of Nutrition at Harvard Chan School and an associate member at the Broad Institute.
“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. Our study suggests that caffeinated coffee or tea consumption can be one piece of that puzzle.”
Why Researchers Are Studying Lifestyle Factors
Preventing dementia before symptoms begin is especially important because current treatments remain limited and usually provide only modest improvements once the disease develops. For this reason, scientists are increasingly examining how everyday lifestyle choices, including diet, may influence the risk of developing dementia.
Coffee and tea contain several biologically active compounds, including caffeine and polyphenols. These substances may help protect the brain by reducing inflammation and limiting cellular damage, both of which are associated with cognitive decline.
Even so, previous research on coffee and dementia has produced mixed results. Many earlier studies had relatively short follow-up periods and did not capture detailed information about long term beverage intake. In addition, some studies were unable to examine the full range of cognitive outcomes, from early subjective memory complaints to clinically diagnosed dementia.
Long Term Data Provide Clearer Insights
The NHS and HPFS cohorts help address many of these limitations. Participants repeatedly reported information about their diet, dementia diagnoses, subjective cognitive decline, and objective cognitive performance. Some participants were followed for as long as 43 years.
Using these long running datasets, researchers evaluated how caffeinated coffee, tea, and decaffeinated coffee were associated with dementia risk and cognitive health over time.
Among the more than 130,000 people included in the analysis, 11,033 eventually developed dementia. Men and women who consumed the highest amounts of caffeinated coffee had an 18% lower risk of dementia compared with those who reported little or no intake.
Participants who drank caffeinated coffee also reported lower rates of subjective cognitive decline (7.8% versus 9.5%). Some objective cognitive tests also indicated better overall performance among coffee drinkers.
Caffeine May Play a Key Role
Tea consumption produced similar associations with cognitive health, but decaffeinated coffee did not. This pattern suggests that caffeine may play an important role in the observed protective effects, although further research will be needed to confirm the specific compounds and biological mechanisms involved.
The strongest cognitive benefits appeared in people who drank 2-3 cups of caffeinated coffee or 1-2 cups of tea each day. In contrast with some earlier studies, higher caffeine intake was not linked to harmful effects. Instead, higher consumption levels appeared to offer neuroprotective benefits similar to those seen within the optimal range.
“We also compared people with different genetic predispositions to developing dementia and saw the same results—meaning coffee or caffeine is likely equally beneficial for people with high and low genetic risk of developing dementia,” said lead author Yu Zhang, MBBS, MS, PhD student at Harvard Chan School and a research trainee at Mass General Brigham.
Reference: “Coffee and Tea Intake, Dementia Risk, and Cognitive Function” by 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, 9 February 2026, JAMA.
DOI: 10.1001/jama.2025.27259
Funding: This study was supported by research grants UM1 CA186107, U01 HL145386, U01 CA167552, R01 HL60712, P30 DK46200, R00 DK119412, R01 AG077489, RF1 AG083764, and R01 NR019992 from the National Institutes of Health.
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8 Comments
This is not true my mother-in-law drank coffee for years and still got Alzheimer’s
It’s true. Coffee drinkers have a decreased chance of developing dementia..
Are you saying that all the people in the world who have alzeimers/dementia did not drink tea or coffee regularly. Not possible
So can nicotine. 🚬🧠
My grandma and grandpa drank coffee every day a few times a day their whole adult life. They both got alzimers alzeimers/dementia
It is my hypothesis dehydroepiandrosterone (DHEA) was selected by evolution in the formation of mammalia. It is also my hypothesis that testosterone was directly involved in human evolution because it increases intracellular DHEA. Both of these androgens work together; I think both are necessary for optimal function of our brains in Alzheimer’s disease. Coffee increases testosterone, so, coffee can help with reductions in testosterone but not loss of DHEA. This explains why coffee can be of benefit in individuals who experience loss of testosterone but not DHEA.
As a now 82 year old lay American male with family histories of very mild food allergies and dementia who’s been battling externally imposed mostly mild (now) chronic diseases since 1981, I can state with some certainty that due to failing to include little known contributing factors the study is seriously flawed. Minimally, omitted contributing factors are sub-acute (nearly subclinical) non-IgE-mediated food (minimally) allergy reactions (Dr. Arthur F. Coca, by 1935) that can cause long-term chronic low-grade inflammation, toxic officially (FDA in the US) approved food additives (soy, TBHQ and added MSG, minimally) which can aggravate (extend and/or intensify) practically harmless still very mild individual food allergy reactions to turn them potentially deadly, long-term (months to decades; many individual variables), and excessive related/resultant medical errors. Still, the caffeine factor may be valid.
You should really look into the connection between dementia and tea! When everyone was drinking loose leaf tea there wasn’t as much dementia but with the tea bags and the glue used to seal them the dementia numbers have been rising!