Longitudinal relationship between healthy lifestyle and cognitive function mediated by activities of daily living among middle-aged and older Chinese adults

It has been demonstrated that a healthy lifestyle affects cognitive function in middle-aged and older adults, while the role of activities of daily living (ADL) has not been investigated. This study was based on the China Health and Retirement Longitudinal Study (CHARLS) from the first wave (2011) to the third wave (2015), aiming to examine the mediating role of ADL in this relationship. The sample included 13,227 middle-aged and older adults who participated in the three wave surveys. A battery of tests, including episodic memory and executive function, were used to evaluate cognitive function, and ten variables, including BMI, exercise and other variables were employed to construct healthy lifestyle indicators. A cross-lagged model was utilized to confirm the mediating effect of ADL between healthy lifestyle and cognitive function. The results revealed that T1 healthy lifestyle had a significant negative prediction for T2 ADL (beta =-0.051, P < 0.001). T1 ADL significantly negatively predicted T2 health lifestyle (beta = -0.052, P < 0.001). T1 cognitive function significantly negatively predicted T2 ADL (beta =-0.032, P < 0.001). T2 ADL significantly negatively predicted T3 cognitive function (beta = -0.103, P < 0.001). T2 cognitive function significantly negatively predicted T3 ADL (beta = -0.003, P < 0.001). After adjustment for covariates, T2 ADL negatively mediated the association between T1 healthy lifestyle (beta = -0.118, P < 0.001) and T3 cognitive function (beta = -0.215, P < 0.001). The model explained 8.2% of the variance in T3 cognitive function. More healthy lifestyles are the protective factors for cognitive impairment and partially benefit work through better ADL ability.