BACKGROUND: 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.

METHODS: 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.

RESULTS: 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.

CONCLUSIONS: 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.