Ever wonder if your morning coffee or afternoon tea truly gives your brain a boost? Emerging scientific evidence suggests you might be onto something. A significant new study indicates that regular, moderate consumption of caffeinated coffee and tea offers tangible cognitive advantages. Specifically, enjoying two to three cups of coffee or one to two cups of tea each day appears to be key.
Over several decades, participants in this extensive research, totaling 131,821 individuals observed for up to 43 years, showed a reduced likelihood of developing dementia compared to those who consumed little to no caffeine. “This is a very large, rigorous study conducted long term among men and women that shows that drinking two or three cups of coffee per day is associated with reduced risk of dementia,” noted Dr. Aladdin Shadyab, an associate professor of public health and medicine at the University of California, San Diego, who was not directly involved in the research.
While these findings, published in JAMA, don’t definitively prove that caffeine *causes* these positive effects, they strongly suggest a correlation. Independent experts highlight that the study meticulously accounted for numerous confounding factors such as existing health conditions, medication use, dietary habits, educational background, socioeconomic status, family history of dementia, body mass index, smoking, and mental health. Remarkably, the link between caffeine consumption and reduced dementia risk remained consistent, even for individuals with genetic predispositions to Alzheimer’s or other forms of dementia. The National Institutes of Health-funded study focused on overall dementia risk rather than specific types.
Previous research on caffeine’s cognitive benefits has yielded mixed results, often due to limitations like shorter study durations or single-point dietary assessments. However, this new study supports an expanding body of work suggesting that caffeinated coffee can indeed reduce the risk of age-related chronic diseases, as Dr. Shadyab pointed out.
The study tracked participants from two prominent, long-term investigations: the Nurses’ Health Study (women) and the Health Professionals Follow-up Study (men). Starting in their mid-40s or early 50s, these individuals regularly completed surveys on their diet, health, and lifestyle. Over the course of the study, 11,033 participants were diagnosed with dementia, based on death certificates or physician records. Compared to minimal or non-caffeine drinkers, those who consumed between one and five eight-ounce cups of caffeinated coffee daily saw approximately a 20 percent reduction in dementia risk. Similarly, drinking at least one cup of caffeinated tea per day was associated with about a 15 percent lower risk.
Interestingly, the protective benefits plateaued after about two and a half cups of coffee per day. Dr. Daniel Wang, the study’s senior author and an epidemiologist specializing in neurodegenerative diseases at Mass General Brigham, suggests this might be due to the body’s limit in metabolizing the active compounds found in these beverages. Dr. Wang, a daily consumer of roughly three cups each of coffee and green tea, noted that the study didn’t identify any negative impacts from higher caffeine intake. However, Dr. Fang Fang Zhang, an epidemiologist at Tufts University’s Friedman School of Nutrition Science and Policy (not involved in this study), cautions that excessive caffeine can potentially disrupt sleep or heighten anxiety, based on other research.
In her own 2025 study, which connected caffeine to reduced mortality, Dr. Zhang’s team observed that benefits didn’t increase beyond three cups. She also noted that adding substantial amounts of milk or sugar seemed to negate these mortality benefits, a factor not tracked in the current dementia study.
Beyond objective dementia diagnoses, the study also investigated subjective cognitive decline – individuals’ self-reported perceptions of memory or thinking issues, which often precede dementia. Participants with higher caffeine intake were less likely to report these early signs of cognitive decline. A subgroup of about 17,000 women over 70 underwent regular cognitive testing. Those who consumed more caffeine generally performed better for their age, suggesting a cognitive decline slowed by approximately seven months, according to Dr. Wang.
Scientists theorize that caffeine may safeguard brain health through compounds that reduce neuroinflammation or support healthy vascular function. It’s also believed to enhance insulin sensitivity, thereby offering protection against diabetes, a known risk factor for dementia. Dr. Shadyab clarifies that these findings aren’t a directive for non-caffeine drinkers to start. Rather, he states, “it is reassuring to those who currently drink coffee that it may reduce risk of dementia.” For those who don’t typically consume caffeine, Dr. Zhang suggests a cautious approach: “give it a try,” starting with small quantities to gauge sensitivity.
The protective link between caffeine and reduced dementia risk was most pronounced in individuals under 75. Dr. Wang emphasized that since cognitive impairment unfolds over many years, adopting healthy habits, including moderate caffeine intake, ideally before midlife—could offer greater benefits. While the study participants were medical professionals, potentially differing from the general population, Dr. Zhang noted that higher caffeine consumers within the group were also more likely to smoke and drink alcohol. This suggests they weren’t inherently healthier than the average American, lending more weight to the caffeine connection.
Researchers acknowledge that they couldn’t entirely rule out all external factors. For instance, they pondered if some participants chose decaf due to underlying health conditions that might independently contribute to dementia, rather than decaf itself being a cause. The study also leaves some questions unanswered, such as which specific types of coffee or tea offer the best cognitive benefits – whether it’s a premium Darjeeling or a humble office brew.