Dissociating apathy and depression in Parkinson disease.

OBJECTIVE

To examine the hypothesis that apathy is a core feature of Parkinson disease (PD) and that apathy can be dissociated from depression.

METHODS

Eighty patients with PD and 20 patients with dystonia completed depression and apathy measures including the Marin Apathy Evaluation Scale (AES), Beck Depression Inventory (BDI), and Centers for Epidemiologic Studies-Depression Scale (CES-D).

RESULTS

There was a significantly higher severity and frequency of apathy in PD (frequency = 51%, 41/80) than in dystonia (frequency = 20%, 4/20). Apathy in the absence of depression was frequent in PD and did not occur in dystonia (PD = 28.8%, dystonia = 0%).

CONCLUSIONS

Patients with Parkinson disease (PD) experienced significantly higher frequency and severity of apathy when compared with patients with dystonia. Apathy may be a "core" feature of PD and occurs in the absence of depression.