title: Neuroimaging of depression in Parkinson's disease: a review.
abstract: BACKGROUND
  Depression is the most common psychiatric manifestation in patients with Parkinson's disease (PD). In addition, depressive symptoms may be considered to be a prodromal manifestation of PD. In recent years, the association between PD and depression has been the focus of neuroimaging studies using functional and structural techniques.
  
  
  METHODS
  The aim of this study was to review the main neuroimaging studies assessing the comorbidity between depression and PD. Literature searches were conducted to find the major neuroimaging studies that consider primarily the comorbidity between depression and PD using the indices Web of Science and Lilacs.
  
  
  RESULTS
  In total, 296 papers were identified, and 18 of these studies were selected for the current review. The principal neuroimaging technique used was SPECT. The structural neuroimaging studies that have evaluated the impact of current or previous bouts of depression on the neurodegenerative process of PD are scarce and inclusive. The instruments that were used to evaluate depression differed among the studies. Several brain regions appear to be involved in depression, particularly the limbic system and the basal ganglia. In addition, the serotonergic, dopaminergic, and noradrenergic systems also appear to be associated with depressive symptoms in PD.
  
  
  CONCLUSIONS
  Several brain regions and neurotransmitter systems are involved in depression in PD; however, the variety of criteria used to evaluate depressive symptoms precludes more specific conclusions.
authors.affiliation: Department of Neuroscience and Behavior, Ribeirão Preto Medical School, University of São Paulo, and INCT Translational Medicine (CNPq), São Paulo, Brazil.
authors.forename: Marcos Hortes N
authors.initials: MH
authors.lastname: Chagas
authors.forename: Ila M P
authors.initials: IM
authors.lastname: Linares
authors.forename: Giovana Jorge
authors.initials: GJ
authors.lastname: Garcia
authors.forename: Jaime E C
authors.initials: JE
authors.lastname: Hallak
authors.forename: Vitor
authors.initials: V
authors.lastname: Tumas
authors.forename: José Alexandre S
authors.initials: JA
authors.lastname: Crippa
mesh_terms: D001921:Brain / Q000473:pathology*; D003863:Depression / Q000175:diagnosis* / Q000209:etiology / Q000473:pathology; D056324:Diffusion Tensor Imaging; D004453:Echoencephalography; D006801:Humans; D008279:Magnetic Resonance Imaging; D059906:Neuroimaging; D010300:Parkinson Disease / Q000175:diagnosis* / Q000473:pathology / Q000523:psychology; D049268:Positron-Emission Tomography; D015899:Tomography, Emission-Computed, Single-Photon