Apathy does not equal depression in Parkinson disease

Abstract

In this issue, Kirsch-Darrow et al.1 examine the hypothesis that apathy is a feature of Parkinson disease (PD) that can be dissociated from depression. The authors evaluated 80 subjects with PD and 20 comparison subjects with dystonia using validated apathy and depression rating scales. About half of the PD group had apathy compared with 20% of the dystonia group. The proportion of subjects who had apathy in the absence of depression was substantial with PD but nonexistent in those with dystonia. This difference between the groups remained significant after controlling for age and gender. The authors conclude that apathy is a core feature of PD that can be present in the absence of depression. Apathy is a mental state that has been variably defined but is characterized by diminished goal-directed speech, motor activity, and emotion. Although patients demonstrate a general sense of indifference, the mood in apathy is neutral. This is different from depression, where mood is distinctly negative and causes emotional suffering. Apathy can occur in the setting of depression but has been shown, in most studies, to correlate best …