Background: Research on quality of life (QOL) with Parkinson’s disease (PD) has examined direct influencing factors, not mediators. The study aim was to explore whether PD severity and poor cognitive function may decrease physical and mental QOL by reducing activities of daily living (ADL) and increasing depression in sequence.
Methods: We conducted a cross-sectional questionnaire study of 150 PD hospital patients in China. PD severity, cognitive function, ADL, depression, and QOL were evaluated. We used structural equation modeling to analyze the mediating effects of ADL and depression on the association between PD severity/cognition and physical (PCS) and mental (MCS) QOL.
Results:There was a significant mediating effect of PD severity on PCS via ADL and depression (95%CI: −0.669, −0.026), and a significant direct effect (p<0.001). The mediating effect of PD severity on MCS via ADL and depression was significant (95%CI: −2.135, −0.726), but there was no direct effect (p = 0.548). There was a significant mediating effect of cognitive function on PCS via ADL and depression (95%CI: 0.025, 0.219) and a significant direct effect (p<0.001). The mediating effect of cognitive function on MCS via ADL and depression was significant (95%CI: 0.256, 0.645), but there was no direct effect (p = 0.313). The PCS models showed a partial mediation, and the MCS models showed a complete mediation, of ADL and depression.
Conclusions:PD severity and cognitive function increase depression by reducing ADL, leading to lower QOL, and directly or indirectly affect PCS and MCS through different pathways.