Anxiety disorders in Parkinson's disease: prevalence and risk factors

Anxiety disorders are common in Parkinson's disease (PD) patients, yet are poorly studied. We examined the prevalence of anxiety disorders in PD, investigated the association between anxiety, and presentation and progression of PD, and studied for the first time the contribution of putative risk factors for anxiety in PD. A case-series of 79 PD patients recruited from neurology out-patient clinics was examined for anxiety disorders using the DSM-IV criteria. The Unified Parkinson's Disease Rating Scale and the Hoehn and Yahr Staging of PD were employed to understand the relationship between anxiety disorders, and the clinical presentation and severity of PD. A validated survey assessed putative risk factors for anxiety in PD. Twenty-five percent of PD patients were diagnosed with anxiety. Panic disorder, generalised anxiety disorder and social phobia were prevalent anxiety disorders. Comorbid depression with anxiety was observed (14%). The severity but not the duration of PD was positively related to anxiety. PD patients with postural instability and gait dysfunction symptom clustering were more likely to experience anxiety than tremor-dominant patients. While levodopa dosage had no relationship to anxiety, experience of dyskinesias or on/off fluctuations increased the risk. Lateralisation of PD had no association with anxiety. Anxiety disorders decreased with age and young onset PD patients were more likely to experience anxiety than the late onset subjects. Anxiety adds to the complexity of PD, lowering patients' quality of life. Future research can be directed to identify reactive and organic nature of anxiety in PD.