With the global aging of the population, the interaction between frailty syndrome in middle-aged and elderly people, depressive symptoms, and cognitive decline has attracted increasing attention. The vicious cycle formed by these three factors significantly reduces quality of life and increases the burden on medical care. Currently, there is still insufficient longitudinal evidence in China on the dynamic relationship between depressive symptoms and cognitive function in frail populations

A total of 1279 middle-aged and elderly people who met the criteria for frailty were included in the study based on data from the China health and retirement longitudinal study (CHARLS) from 2011 to 2018. Group-based trajectory modeling (GBTM) was used to identify cognitive function trajectories, and model fitting was evaluated using indicators such as Bayesian information criterion (BIC) and average posterior probability. A multivariable logistic regression model was used to analyze the association between depressive symptoms in frail individuals and different cognitive trajectories, adjusting for confounding factors such as demographic characteristics and comorbid chronic diseases

This study identified six cognitive function development trajectories and analyzed the association between depressive symptoms and different cognitive trajectories. The results showed that, compared with the cognitive Normal-stable group, depressive symptoms were significantly associated with all adverse cognitive trajectories. In the unadjusted model, depressive symptoms increased the risk of the cognitive impairment-rapid decline group by 1.72 times (OR = 2.72, 95 % CI 1.56–4.72) and increased the risk of the cognitive Normal-late rapid decline group by 0.95 times (OR = 1.95, 95 % CI 1.19–3.18). After adjusting for multiple factors, this association remained significant. In the fully adjusted model (model 5), the risk for the cognitive impairment-rapid decline group further rose to 2.10 times (OR = 3.10, 95 % CI 1.69–5.69), while the risk for the cognitive impairment-persistent low level group (OR = 1.69, 95 % CI 1.05–2.72), the cognitive Normal-fluctuating group (OR = 1.65, 95 % CI 1.03–2.62), and other adverse trajectory groups also showed significant associations (all p < 0.05). These results indicate that depressive symptoms are an independent risk factor for multiple adverse cognitive function trajectories, with the strongest association observed in the rapid cognitive decline group

This study found that depressive symptoms are an independent risk factor for cognitive decline in middle-aged and elderly frail populations, particularly significantly predicting rapid cognitive decline and persistent cognitive impairment. Depressive symptom screening demonstrates significant clinical value in cognitive health management for frail middle-aged and older adults, particularly for identifying individuals at highest risk of rapid cognitive decline