Temporal Sequence of Cognitive Function and ADLs and Mediation Effect of Apathy in Parkinson’s Disease: Cross-Lagged Analyses

Objectives To explore the temporal sequence between cognitive function and activities of daily living (ADLs) in patients with Parkinson’s disease (PD) and investigate whether apathy mediates these effects.Methods We recruited 486 patients from the Parkinson’s Progression Marker Initiative. We constructed a cross-lagged panel model to explore the temporal sequence between cognitive function and ADLs and analyzed the longitudinal mediating effect of apathy on the relationship between cognitive function and ADLs.Results The slopes of ADLs and cognitive function were significant (p < .001), and lower levels of cognitive function indicated lower ADLs, suggesting that a decreased cognitive performance preceded ADLs decline. Cognitive function influenced apathy (negatively) (p < .001) and ADLs (p < .001). A significant indirect effect of cognitive function on ADLs through apathy was revealed by bias-corrected bootstrapping (β = 0.181, p < .001).Conclusions The rate of change in cognitive function was significantly correlated with that of ADLs, and a decreased cognitive performance preceded ADLs decline. Cognition was indirectly related to ADLs through apathy.Clinical implications The rate of change in cognitive function in patients with PD was correlated with that of ADLs, and a decreased cognitive performance preceded ADLs decline. Reducing apathy represents a promising approach to reducing the impact of cognitive decline on ADLs.