Drinking a few cups of coffee or tea daily may be associated with a lower risk of developing dementia, according to a long-term study published February 9 in the Journal of the American Medical Association. Researchers found that consuming approximately two to three cups of caffeinated coffee, or one to two cups of tea, each day was linked to a reduced risk compared to those who did not consume either beverage.
The analysis, encompassing data collected over several decades from the Nurses’ Health Study and the Health Professionals Follow-up Study, involved more than 130,000 individuals who were initially free of cancer, Parkinson’s disease, and dementia. Participants regularly completed dietary questionnaires, and researchers tracked dementia diagnoses through death records and self-reporting.
Among those who did not drink caffeinated coffee, researchers observed 330 fresh cases of dementia per 100,000 people per year. This rate decreased to 229 per 100,000 per year among moderate coffee consumers. While the highest coffee consumption likewise showed a lower rate, adjustments for factors like age and smoking revealed that both moderate and high consumption were associated with similar risk reductions – 19 and 18 percent, respectively. Tea consumption also demonstrated a protective effect, though the study did not differentiate between caffeinated and decaffeinated tea.
The study indicated that moderate daily coffee consumption for women averaged around 2.5 cups, with higher consumers reaching approximately 4.5 cups daily. Men in the study tended to consume slightly less. Researchers also noted that individuals who drank more coffee were generally younger and had a higher likelihood of being smokers.
Researchers did not determine the specific mechanisms by which coffee or tea might lower dementia risk, but suggested that caffeine’s potential anti-inflammatory properties could play a role. Previous research has indicated that caffeine may reduce inflammation, and other compounds found in coffee and tea may mitigate oxidative stress, a process that causes cellular damage. The complex relationship between diet and dementia development remains an area of ongoing investigation.
The study team emphasized that the relationship between diet and dementia is complex and that a single beverage is unlikely to be a sole preventative measure.
