Factors associated with depression in Parkinson's disease

Abstract

Background: Depression is common in Parkinson's disease (PD) and contributes significantly to a reduced quality of life in PD patients. The determinants of depression in PD are complex and poorly understood. We investigated the factors associated with depression in PD.

Methods: PD patients were recruited from Neurology clinics. A validated method was used to screen for a lifetime history of depression. 'Depressed' patients were identified by a score of >6 in the Geriatric Depression Scale (GDS-15) or by having had prescribed treatment for depression. 'Never depressed' patients were recognised by a score of <5 in the GDS-15 with no signs of a history of depression. A newly developed and validated questionnaire was used to collect other information.

Results: Depression was identified in 66% of the 639 PD patients who met the inclusion criteria. Depression was associated with an increased severity of illness as evidenced by higher Unified PD Rating Scale scores and a higher Hoehn and Yahr stage. Other clinical factors associated with disease severity were also more frequently observed in depressed patients. Similar to findings in non-PD samples, depressed PD patients were more likely to have a lower education level, a history of smoking and to regularly use non-aspirin based NSAIDs or analgesics. Comorbidities such as anxiety, memory problems, hallucinations, sleep disturbances and postural hypotension were more common in depressed PD patients.

Limitations: To avoid patient exhaustion of over-surveying, some factors within the psychological domain were not examined.

Conclusion: Our results provide a focus for future intervention strategies.