Quality of life and non-motor symptoms in Parkinson's disease patients with subthreshold depression.

The role of subthreshold depression (subD) in Parkinson's Disease (PD) is not clear. The present study aimed to compare the quality of life (QoL) in PD patients with subD vs patients with no depressive disorder (nonD). Factors related to subD were identified. PD patients and controls recruited from the COPPADIS cohort were included. SubD was defined as Judd criteria. The 39-item Parkinson's disease Questionnaire (PDQ-39) and the EUROHIS-QOL 8-item index (EUROHIS-QOL8) were used to assess QoL. The frequency of depressive symptoms was higher in PD patients (n = 694) than in controls (n = 207) (p < 0.0001): major depression, 16.1% vs 7.8%; minor depression, 16.7% vs 7.3%; subD, 17.4% vs 5.8%. Both health-related QoL (PDQ-39; 18.1 ± 12.8 vs 11.6 ± 10; p < 0.0001) and global QoL (EUROHIS-QOL8; 3.7 ± 0.5 vs 4 ± 0.5; p < 0.0001) were significantly worse in subD (n = 120) than nonD (n = 348) PD patients. Non-motor Symptoms Scale (NMSS) total score was higher in subD patients (45.9 ± 32 vs 29.1 ± 25.8;p < 0.0001). Non-motor symptoms burden (NMSS;OR = 1.019;95%CI 1.011-1.028; p < 0.0001), neuropsychiatric symptoms (NPI; OR = 1.091; 95%CI 1.045-1.139; p < 0.0001), impulse control behaviors (QUIP-RS; OR = 1.035; 95%CI 1.007-1063; p = 0.013), quality of sleep (PDSS; OR = 0.991; 95%CI 0.983-0.999; p = 0.042), and fatigue (VAFS-physical; OR = 1.185; 95%CI 1.086-1.293; p < 0.0001; VAFS-mental; OR = 1.164; 95%CI 1.058-1.280; p = 0.0001) were related to subD after adjustment to age, disease duration, daily equivalent levodopa dose, motor status (UPDRS-III), and living alone. SubD is a frequent problem in patients with PD and is more prevalent in these patients than in controls. QoL is worse and non-motor symptoms burden is greater in subD PD patients.