BACKGROUND AND PURPOSE: 

• Consumption of coffee or caffeine may help prevent dementia, possibly by reducing amyloid-β (Aβ) in the brain 
  • Data is currently limited  
• Matsushita et al. (Journal of the American Geriatrics Society, 2021) examined association between caffeine consumption and dementia risk  

METHODS: 

• Cohort study 
  • Murakami cohort study targeted all residents between 40 and 74 years, living in Murakami city, Sekikawa village, and Awashimaura village of Niigata Prefecture in Japan 
• Participants 
  • Adults aged 40 to 74 years  
  • Japanese Cohort   
• Exposures 
  • Consumption levels of coffee or green tea 
• Study design 
  • Caffeine consumption was estimated from self-reported amount of coffee or green tea consumption  
  • Incidence of primary outcome was determined from a long-term care insurance database 
  • Covariate Analyses: Demographic factors | BMI | Physical activity | Energy | Smoking | Drinking | Disease history 
  • Adjusted hazard ratio (HR) calculated using Cox proportional hazards models 
• Primary outcome 
  • Incident dementia 

RESULTS: 

• 13,757 participants 
  • Follow-up: 8.0 years 
  • Dementia cases during the study period: 309 
• Compared to participants who consumed <26 ml (0.9 oz) of coffee per day (1^st quintile), those that consumed ≥326 ml (11 oz) per day (5^th quintile) had reduced dementia risk  
  • HR 0.49 (95% CI, 0.30 to 0.79) 
  • Adjusted p for trend=0.0014 
  • In subgroup analysis 
    • Overall significant among men, not women  
    • Among ≥60 years, 5^th quintile had lower HR (0.5; 95% CI, 0.29 to 0.85) for both men and women  
• Compared to those who did not consume coffee, higher cups per day was associated with reduced dementia risk in men and women combined    
  • 2 to 2.9 cups/day: HR 0.69 (95% CI, 0.48 to 0.98) 
  • ≥3 cups/day: HR 0.53 (95% CI, 0.31 to 0.89, respectively 
• Participants with higher caffeine consumption had a significantly lower HR than those who consumed <92 mg per day 
  • adjusted p for trend=0.0004 
• There was no association between green tea consumption and reduced dementia risk overall but marginal significance seen in the 60 to 69 years age subgroup 

CONCLUSION: 

• Higher levels of daily coffee and caffeine intake were dose-dependently associated with reduced dementia risk, especially among men  
• Authors suggest possible reasons for differences between men and women  
  • Men have a higher degree of oxidative stress and benefits of caffeine may include antioxidant effect  
  • Effects of caffeine on sex hormones may differ by sex  

Learn More – Primary Sources: 

Association of coffee, green tea, and caffeine with the risk of dementia in older Japanese people 

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