Relationship of depression, disability, and quality of life in Parkinson's disease: A hospital-based case-control study

Background : Depression, anxiety, cognitive impairment, sleep disturbances are common neuropsychiatric manifestations in Parkinson′s disease (PD).
Aims : To compare the prevalence and severity of depression in PD with a group of patients with other chronic medical illnesses and ascertain the relationship of depression with disability and quality of life in PD.
Settings and Design : Hospital-based prospective case-control study.
Patients and Methods : Forty-six PD patients and 30 non-PD controls having chronic medical conditions were studied. All were assessed by Beck Depression Inventory (BDI) and Montgomery Asberg Depression Rating Scale (MADRS), World Health Organization Disability Assessment Schedule (WHODAS II) and World Health Organization Quality of Life Scale-Brief Version (WHOQOL-Bref).
Statistical Analysis Used : SPSS Version 13.0 was used for analysis which included descriptive tests, independent t test, chi-square test, Fisher′s exact test, and Pearson′s correlation coefficient.
Results : The prevalence of depression was higher and more severe in PD than controls (MADRS: 54.3% vs 23.3%, P<0.01; BDI 49.9% vs 23.4%, P<0.05). PD patients had significantly greater overall disability than controls (36.8±19.4 vs 15.1±15.4; P<0.001), and the difference was observed in all six domains of WHODAS II.
Conclusions : PD patients had inferior quality of life than controls in all four spheres of WHOQOL-Bref. In PD, depression correlated positively with various domains of disability (P<0.001) and negatively with quality of life (P<0.001). In summary, the prevalence and severity of depression is significantly higher in PD than can be explained by chronic illness. Depression plays an important role in determining the disability and quality of life.