Moderate daily consumption of caffeinated coffee or tea may be linked to a reduced risk of dementia and slower cognitive decline, according to a large, long-term study published this week. Researchers found that individuals who regularly consumed two to three cups of caffeinated coffee per day had an 18% lower risk of developing dementia compared to those who drank little to no caffeine.
The study, published in , in the journal JAMA, analyzed data from 131,821 participants in the Nurses’ Health Study and the Health Professionals Follow-Up Study, tracking them for up to 43 years. Participants underwent repeated assessments of their diet, cognitive function, and any instances of dementia or cognitive decline.
Researchers compared the effects of caffeinated coffee, tea, and decaffeinated coffee on dementia risk and overall cognitive health. The findings suggest a specific benefit associated with caffeine, as no similar association was observed among those who consumed decaffeinated coffee.
“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.
How Caffeine May Protect Cognitive Function
The precise mechanisms by which caffeine may offer neuroprotective benefits are still being investigated. However, experts believe that bioactive compounds found in coffee and tea, such as polyphenols and caffeine itself, may play a role in reducing inflammation and cellular damage within the brain. These processes are known contributors to the development of dementia.
The study also indicated that regular consumption of caffeinated coffee was associated with a lower prevalence of subjective cognitive decline – that is, individuals’ own perceptions of memory or thinking difficulties – with 7.8% of coffee drinkers reporting such decline compared to 9.5% of those who consumed little to no caffeine. Some measurements suggested that those who drank caffeinated coffee also performed slightly better on objective tests of overall cognitive function.
The Importance of Moderation and a Holistic Approach
While the findings are encouraging, researchers emphasize that the effect size is relatively small and that caffeine consumption is likely just one piece of a larger puzzle when it comes to protecting cognitive health. “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,” Dr. Wang explained. “Our study suggests that caffeinated coffee or tea consumption can be one piece of that puzzle.”
Early prevention is particularly crucial for dementia, as current treatments offer limited benefits, typically providing only modest improvement once symptoms appear. Focusing on lifestyle factors, including diet, is therefore a key area of research.
The study’s findings align with a growing body of evidence suggesting potential cognitive benefits from moderate caffeine intake. The optimal amount appears to be around two to three cups of coffee or one to two cups of tea per day. However, it’s important to note that individual responses to caffeine can vary, and excessive consumption may have adverse effects.
Study Details and Participant Demographics
The research involved a prospective cohort study, meaning participants were followed over time to observe the development of dementia and changes in cognitive function. The 131,821 participants included both men and women from the Nurses’ Health Study and the Health Professionals Follow-Up Study. Over the course of the study, 11,033 participants were diagnosed with dementia.
Researchers repeatedly assessed participants’ dietary habits, subjective cognitive decline, and objective cognitive function throughout the study period. This allowed them to compare how different levels of caffeinated coffee, tea, and decaffeinated coffee intake influenced dementia risk and cognitive health.
Looking Ahead
Further research is needed to fully understand the complex relationship between caffeine, cognitive function, and dementia risk. Future studies could explore the optimal dosage of caffeine, the specific types of coffee and tea that offer the greatest benefits, and the underlying biological mechanisms responsible for these effects. For now, the findings offer a reassuring message for moderate coffee and tea drinkers and highlight the potential role of dietary interventions in promoting brain health.
