JAMA：华人学者研究发现，每天2-3杯咖啡或1-2杯茶，痴呆风险更低、大脑认知功能更好

Core Viewpoint - The study published by Harvard University indicates that the consumption of caffeinated coffee and tea is associated with a reduced risk of dementia and slightly better cognitive function, while decaffeinated coffee shows no significant association with dementia risk [2][4][10]. Group 1: Study Overview - The research involved a prospective cohort study with 131,821 participants from two cohorts: the Nurses' Health Study (NHS) and the Health Professionals Follow-up Study (HPFS), with a follow-up period of up to 43 years [4][5]. - Participants were free of cancer, Parkinson's disease, or dementia at baseline, and dietary intake was assessed every 2-4 years using validated food frequency questionnaires [4][5]. Group 2: Key Findings - During the follow-up, 11,033 new cases of dementia were recorded among participants [5]. - The analysis showed that the highest quartile of caffeinated coffee consumption had a significantly lower dementia risk compared to the lowest quartile (141 cases vs 330 cases per 100,000 person-years; risk ratio 0.82) [6]. - Subjective cognitive decline was lower in the highest caffeinated coffee consumption group (7.8% vs 9.5%; prevalence ratio 0.85) [6]. Group 3: Consumption Patterns - No significant association was found between decaffeinated coffee and dementia risk or cognitive function [7]. - A non-linear inverse relationship was observed between the intake of caffeinated coffee and tea and cognitive outcomes, with the most significant protective effects noted at moderate consumption levels (2-3 cups of caffeinated coffee and 1-2 cups of tea daily) [7][10]. Group 4: Implications - The results suggest that higher consumption of caffeinated coffee and tea is linked to a lower risk of dementia and better cognitive function, highlighting caffeine as a potential key active ingredient, while polyphenols in tea may also play a synergistic role [10].