The mediating effect of psychological distress on cognitive function and physical frailty among the elderly: Evidence from rural Shandong, China

•The prevalence of physical frailty and cognitive impairment among the elderly in rural China was 18.0% and 22.4%.•Cognitive function was correlated with physical frailty.•Cognitive function was positively associated with higher level of PD.•Elderly with higher level of PD had a higher probability of suffering from physical frailty.•The effect of cognitive function on physical frailty was partially mediated by PD among the elderly in rural China. Few studies have explored the underlying mechanism between physical frailty and cognitive function. The aim of this study is to explore the mediating role of psychological distress (PD) for the association between cognitive function and physical frailty among the elderly in rural China. A total of 3,242 rural older adults were included in the analysis. Logistic regression and Bootstrap analyses were employed to explore the association between cognitive function, PD and frailty, and the mediating role of PD. This study found that the prevalence of frailty and cognitive impairment among the elderly in rural China was 18.0%, 22.4%. After adjusted for controlling variables, cognitive function was significantly associated with high level of PD, and elderly with higher level of PD had a higher probability of suffering from frailty. PD played a partially mediating effect in cognitive function and frailty and the mediating effect of PD can explain the 11.0% of the total effect of cognitive function on frailty. The data were cross-sectional, thus the causal relationship between variables could not be determined. The main variables in this study were measured by self-report information, which might result in recall bias. This study provide evidence that the effect of cognitive function on physical frailty was partially mediated by PD among the elderly in rural China. Primary health care should strengthen the screening of PD characterized by depression and anxiety, and strive to improve the physical and psychological well-being of rural elderly in China.