ON-OFF Effects of Dopaminergic Therapy on Psychiatric Symptoms in Parkinson's Disease.

Psychiatric manifestations of Parkinson's disease (PD) are a cause of significant disability and the impact of dopaminergic medications is unclear. Using standardized rating scales, the authors tested the hypothesis that anxiety, depression, and apathy vary in the ON versus OFF states in PD in 33 PD patients and 29 healthy age- and education-matched controls. PD patients had significantly higher anxiety, depression, and apathy scores than control participants, regardless of ON-OFF state. Anxiety scores were higher in PD patients on relative to off dopaminergic medication. The ON-OFF difference in anxiety related to degree of improvement in motor function but not illness duration.