A large-scale study conducted in the United States has found that moderate consumption of caffeinated coffee and tea may be associated with a lower risk of developing dementia and improved preservation of cognitive function over time. The research, led by scientists from the Harvard T.H. Chan School of Public Health in collaboration with Mass General Brigham and the Broad Institute of MIT and Harvard, adds to growing evidence that everyday dietary habits can influence brain health during ageing.
Published in the peer-reviewed journal JAMA, the study analysed health data from more than 130,000 participants over several decades, examining the relationship between beverage consumption and cognitive outcomes.
Moderate Intake Associated with Better Cognitive Outcomes
According to the findings, individuals who regularly consumed two to three cups of caffeinated coffee per day or one to two cups of caffeinated tea daily demonstrated a lower likelihood of developing dementia compared with those who consumed little or none of these beverages.
The researchers also observed better performance in cognitive assessments and fewer reports of subjective memory decline among moderate consumers. Importantly, these associations were identified in both participants with and without a genetic predisposition to dementia, suggesting that lifestyle factors may contribute to brain health regardless of inherited risk.
Caffeine and Plant Compounds May Play a Role
The investigators noted that the protective association was observed only with caffeinated coffee, whereas decaffeinated coffee did not demonstrate the same relationship. This finding suggests that caffeine may contribute to the observed benefits, although other naturally occurring compounds present in coffee and tea, including polyphenols and antioxidants, may also be involved.
These bioactive substances have previously been associated with reduced inflammation and protection against oxidative stress, biological processes that are recognised as contributors to age-related cognitive decline and several neurodegenerative disorders.
However, the researchers emphasised that the study demonstrates an association rather than direct causation, meaning it cannot prove that coffee or tea alone prevent dementia.
More Is Not Necessarily Better
One of the notable conclusions of the research was that increasing consumption beyond the moderate levels identified did not appear to provide additional cognitive benefits. This supports current evidence suggesting that moderation remains the most appropriate approach when consuming caffeinated beverages.
The authors also highlighted that coffee and tea should not be viewed as standalone preventive measures but rather as components of a broader strategy for maintaining brain health.
Brain Health Depends on Multiple Lifestyle Factors
Experts involved in the study stressed that reducing the risk of dementia requires a comprehensive approach that extends beyond dietary choices. Regular physical activity, a balanced diet, adequate sleep, cardiovascular risk management, social engagement and lifelong cognitive stimulation continue to be recognised by international health organisations as key factors in supporting healthy brain ageing.
The findings from the United States reinforce the growing body of scientific literature suggesting that moderate consumption of caffeinated coffee and tea may form part of a healthy lifestyle associated with better cognitive function. Nevertheless, researchers recommend that dietary choices should always be personalised according to individual health conditions and discussed with healthcare professionals when necessary.