Depression antedating the onset of Parkinson's disease.

Neurological and depressive symptoms in a subtype of Parkinson's disease (PD), in which a depressive state precedes the clinical manifestation of neurological symptoms, were examined on the basis of clinical observations for 3 years or more. PD, in which depression preceded, was different from PD with preceding neurological symptoms, in the severity of not only neurological but also depressive symptoms. These results suggest that PD in which depression precedes neurological symptoms is a specific subtype of PD. It was speculated that the differences in clinical symptoms might be due to a biological background, in particular the dopaminergic system.