Generalized anxiety disorder and the Hamilton Anxiety Rating Scale in Parkinson's disease

UNLABELLED: Anxiety is common in Parkinson's disease (PD), but studies concerning specific anxiety disorders are scarce. Essential psychometric properties of anxiety rating scales are also lacking. OBJECTIVE: To investigate general anxiety disorder (GAD) in PD and psychometric properties of the Hamilton Anxiety Rating Scale (Ham-A). METHOD: Ninety-one PD patients underwent neurological and psychiatric examination, which included the MINI-Plus, the Ham-A and the Hamilton Depression Rating Scale (Ham-D). RESULTS: GAD was present in 30.8% of PD patients. Patients with GAD had longer disease duration (p=0.044) and were in use of higher doses of levodopa (p=0.034). They also tended to have more motor fluctuations and dyskinesias. The group with GAD scored higher in Ham-A (p<0.001), in the somatic (p=0.004) and psychic (p<0.001) subscales of Ham-A, and in Ham-D (p=0.004). The Ham-A showed good internal consistency (Cronbach's alpha=0.893) and a cutoff score of 10/11 is suggested to screen for GAD. CONCLUSION: GAD is frequent in PD and the Ham-A may be a useful instrument to screen for this disorder.