Conceptualization of depression in Parkinson’s disease

AIMS: To discuss the current methodological and conceptual difficulties inherent in characterizing the emotional manifestations of neurodegenerative disease through critically reviewing depression as a manifestation of idiopathic Parkinson’s disease (PD). METHODS: Selective literature review of the neurobiological, psychological, and physical basis of depressive symptoms in PD from 1993–2003, with reference to key earlier articles. CONCLUSIONS: There are difficulties in defining the syndromes of PD itself as well as depression in PD. The use of more conceptually reductionistic definitions of emotion and behavior in comprehensive longitudinal studies of the natural history of PD is recommended.