Fiber-based vegetarian score and the risk of incident dementia among elderly Chinese adults: a prospective cohort study.

Abstract

With the acceleration of population aging, dementia has become a major public health challenge. Although vegetarian diets have been proven to be related to cognitive health in Western populations, there is a lack of longitudinal research evidence in the elderly population in China. This study aims to use data from the China Longitudinal Healthy Longevity Survey (CLHLS) to prospectively explore the association between vegetarian dietary patterns and the risk of dementia. This study included 1,948 elderly individuals aged ≥ 65 years at baseline and without dementia in the CLHLS 2008-2018 cohort. The frequency of intake of 10 types of foods was assessed using a food frequency questionnaire, and a vegetarian dietary score was constructed based on the intake frequency of vegetarian foods (grains, vegetables, fruits, nuts, fungi). During follow-ups in 2010, 2011, 2014, and 2018, dementia onset events were identified through Chinese version of the Mini-Mental State Examination (CMMSE), activities of daily living ability, and self-reported physician diagnoses. The Cox proportional hazards model was used to estimate hazard ratios (HR) and 95% confidence intervals (CI), with adjustment for confounding variables including sociodemographic characteristics, lifestyle, and health status. Subgroup analyses and sensitivity analyses were conducted to evaluate effect modification and the robustness of the results. During the 10-year follow-up period, a total of 53 incident dementia cases (2.7%) were documented. After multivariate adjustment, each 1-point increase in the vegetarian dietary score was associated with a 17% reduction in dementia risk (HR = 0.83, 95% CI: 0.70-0.98, p = 0.031). Compared with participants in the lowest tertile of vegetarian score, those in the intermediate tertile (HR = 0.49, 95% CI: 0.26-0.93, p = 0.028) and the highest tertile (HR = 0.50, 95% CI: 0.23-0.99, p = 0.048) had significantly lower risks of dementia. Subgroup analyses revealed that the protective effect of a vegetarian diet was more pronounced among participants aged < 80 years (HR = 0.62, 95% CI: 0.48-0.80), non-drinkers (HR = 0.81, 95% CI: 0.67-0.97), those without formal education (HR = 0.79, 95% CI: 0.63-0.98), those engaged in physical labor (HR = 0.66, 95% CI: 0.49-0.89), and those married/cohabiting (HR = 0.70, 95% CI: 0.54-0.90). After excluding cases with early onset during follow-up and extreme age values, sensitivity analyses confirmed the robustness of the findings. A vegetarian dietary pattern is significantly associated with a lower risk of dementia in Chinese elderly individuals, and this protective effect varies across demographic and lifestyle subgroups. This study supports the inclusion of vegetarian diets patterns in primary prevention strategies for dementia and highlights their particular application value in specific vulnerable populations.