Depression and apathy in Parkinson's disease.

This article provides an update on depression and apathy in Parkinson's disease (PD), both of which are common but often misunderstood. The diagnosis of depression in PD can be challenging and we still do not have solid evidence on which to base our treatment decisions. Apathy is most commonly seen in the setting of dementia or depression but emerging evidence suggests that it may be a core feature of PD. There are conflicting reports about the effects of deep brain stimulation (DBS) on mood and apathy, but studies suggest that at least some patients may develop depression and apathy after the procedure. Although we are making strides toward a better understanding of depression and apathy in PD, it is clear that more research is needed about these non-motor features.