ABSTRACT
The associations of coffee and tea intake with long-term risk of dementia have not been thoroughly established. Additionally, the potential mediating roles of circulating inflammatory biomarkers in these associations remain less explored. We included 6,001 participants from the Health and Retirement Study (HRS, 2013-2020) and 2,650 participants from the Framingham Heart Study Offspring cohort (FOS, 1998-2018), all free of dementia at baseline. Coffee and tea intake was assessed using a semi-quantitative food frequency questionnaire in both cohorts. Dementia diagnosis was ascertained using a validated algorithm and clinical review panel. Cox proportional hazard models were utilized to evaluate the associations of coffee and tea intake with dementia. Mediation analysis was conducted to examine whether circulating inflammatory biomarkers mediated these associations. During a median follow-up of 7.0 years in HRS and 11.1 years in FOS, 231 individuals in HRS and 204 in FOS developed all-cause dementia. Compared with intake of less than 1 cup of coffee per day, consuming ≥ 2 cups daily had a 28-37% lower risk of dementia (Hazards ratio [HR] = 0.72, 95% confidence interval [CI]: 0.52, 0.99, P-trend = 0.045 in HRS; HR = 0.63, 95% CI: 0.45, 0.90, P-trend = 0.015 in FOS). Compared to non-consumers, moderate tea consumption was associated with a lower dementia risk in HRS (HR = 0.65, 95% CI: 0.48, 0.89 for > 0 to < 1 cup/day; HR = 0.53, 95% CI: 0.30, 0.94 for ≥ 1 to < 2 cups/day), but no significant association was observed in FOS. In the mediation analysis, the association between coffee intake and dementia was partially mediated by interleukin-10 (IL-10, 29.30%), Cystatin C (24.45%), C-reactive protein (CRP, 16.54%), interleukin-1 receptor antagonist (IL-1RA, 11.06%), and soluble tumor necrosis factor receptor-1 (sTNFR-1, 10.78%). In conclusion, higher coffee consumption (≥ 2 cups per day) is associated with a lower risk of dementia, partially mediated by a set of inflammatory biomarkers. Moderate intake of tea (0-2 cups per day) may relate to a lower risk of dementia. Further large-scale observational and interventional studies are warranted to confirm these findings.
