Cross-sectional association between a CLHLS-based diet quality score and screening-defined elevated depressive symptoms among Chinese older adults

BACKGROUND: Depressive symptoms are common in later life and may be related to dietary behaviours. However, dietary habits and depressive symptoms may influence each other, and cross-sectional data cannot establish temporal direction. This study examined the cross-sectional association between a Chinese Longitudinal Healthy Longevity Study (CLHLS)-based diet quality score and screening-defined elevated depressive symptoms among Chinese older adults. METHODS: This cross-sectional study used data from the 2018 CLHLS. Dietary behaviour was assessed using self-reported intake frequency of 13 food groups, with items coded so that higher values indicated higher intake frequency. A CLHLS-based diet quality score was then constructed. Elevated depressive symptoms were assessed using the CESD-10. Multivariable logistic regression was used to examine the association between diet quality and elevated depressive symptoms. False discovery rate correction was applied in exploratory food-group analyses. Sensitivity analyses included multiple imputation with 20 datasets and a modified CESD-10 score excluding the sleep-quality item. RESULTS: Among 15,874 participants in the 2018 CLHLS, 12,069 adults aged 60 years or older had complete dietary and depressive symptom data. In the fully adjusted complete-case model (n = 9,086), each five-point increase in the CLHLS-based diet quality score was associated with lower odds of elevated depressive symptoms (OR = 0.877, 95% CI: 0.844-0.912, p < 0.001). Although statistically significant, the association was modest in magnitude, and explanatory power was limited. The multiple-imputation analysis yielded a similar estimate (pooled OR = 0.890, 95% CI: 0.860-0.922, p < 0.001). The association also remained when depressive symptoms were analysed using the modified CESD-10 score. In exploratory food-group analyses, higher reported intake frequencies of fruit and vegetables were associated with lower odds of elevated depressive symptoms after adjustment. CONCLUSION: The CLHLS-based diet quality score was weakly associated with screening-defined elevated depressive symptoms. These findings should be interpreted as descriptive and hypothesis-generating, rather than causal or sufficient to support clinical or public health dietary recommendations. Longitudinal studies using validated dietary assessment tools are needed.