Cognition, coping, and outcome in Parkinson's disease

Cognitive impairment and depression are common and disabling non-motor symptoms of Parkinson's disease (PD). Previous studies have shown associations between them but the nature of the relationship remains unclear. In chronic illness, problem- or task-oriented coping strategies are associated with better outcome but often require higher level cognitive functioning. The present study investigated, in a sample of patients with PD, the relationships between cognitive function, choice of coping strategies, and a broad index of outcome including depression, anxiety, and health-related quality of life (QoL). It was hypothesized that the coping strategy used could mediate the association between cognition and outcome.

347 participants completed the Coping Inventory for Stressful Situations, the Hospital Anxiety and Depression Scale, the Parkinson's Disease Questionnaire-8, the Unified Parkinson's Disease Rating Scale, and the Addenbrooke's Cognitive Examination-Revised. Structural Equation Modeling was used to test the hypothesized model of cognition, coping, and outcome based on a direct association between cognition and outcome and an indirect association mediated by coping.

Overall, poorer cognition predicted less use of task-oriented coping, which predicted worse outcome (a latent variable comprised of higher depression and anxiety and lower QoL). The analyses suggested a small indirect effect of cognition on outcome mediated by coping.

The findings suggest that patients who fail to employ task-oriented coping strategies may be at greater risk of depression, anxiety, and poor health-related QoL. Even mild to moderate cognitive impairment may contribute to reduced use of task-oriented coping. Suitably adapted cognitive-behavioral approaches may be useful to enable the use of adaptive coping strategies in such patients.