title: Depressive symptoms in PD correlate with higher 5-HTT binding in raphe and limbic structures.
abstract: BACKGROUND
  Depression associated with Parkinson disease (PD) has a different symptom profile to endogenous depression. The etiology of depression in PD remains uncertain though abnormal serotonergic neurotransmission could play a role.
  
  
  OBJECTIVE
  To assess with PET serotonergic function via in vivo serotonin transporter (5-HTT) availability in antidepressant-naive patients with PD.
  
  
  METHODS
  Thirty-four patients with PD and 10 healthy matched control subjects had a clinical battery of tests including the patient-report Beck Depression Inventory-II (BDI-II), the clinician-report Hamilton Rating Scale for Depression (HRSD), and the structured clinical interview for DSM-IV Axis I Disorders (SCID-I). They underwent ¹¹C-DASB PET, a selective in vivo marker of 5-HTT binding in humans.
  
  
  RESULTS
  BDI-II scores correlated with HRSD scores. Ten of 34 patients with PD (29.4%) had BDI-II and HRSD scores above the discriminative cutoff for PD depression though only half of these patients could be classed on SCID-I criteria as having an anxiety/mood disorder. Patients with PD with the highest scores for depression symptoms showed significantly raised ¹¹C-DASB binding in amygdala, hypothalamus, caudal raphe nuclei, and posterior cingulate cortex compared to low score cases, while ¹¹C-DASB binding values in other regions were similarly decreased in depressed and nondepressed patients with PD compared to healthy controls.
  
  
  CONCLUSIONS
  Depressive symptoms in antidepressant-naive patients with PD correlate with relatively higher 5-HTT binding in raphe nuclei and limbic structures possibly reflecting lower extracellular serotonin levels. Our data are compatible with a key role of abnormal serotonergic neurotransmission contributing to the pathophysiology of PD depression and justify the use of agents acting on 5-HTT.
authors.affiliation: MRC Clinical Sciences Centre and Centre for Neuroscience, Faculty of Medicine, Imperial CollegeLondon, UK. marios.politis@imperial.ac.uk
authors.forename: M
authors.initials: M
authors.lastname: Politis
authors.forename: K
authors.initials: K
authors.lastname: Wu
authors.forename: C
authors.initials: C
authors.lastname: Loane
authors.forename: F E
authors.initials: FE
authors.lastname: Turkheimer
authors.forename: S
authors.initials: S
authors.lastname: Molloy
authors.forename: D J
authors.initials: DJ
authors.lastname: Brooks
authors.forename: P
authors.initials: P
authors.lastname: Piccini
mesh_terms: D001596:Benzylamines; D002250:Carbon Radioisotopes; D003863:Depression / Q000175:diagnosis / Q000209:etiology*; D006801:Humans; D008032:Limbic System / Q000378:metabolism*; D010300:Parkinson Disease / Q000523:psychology*; D049268:Positron-Emission Tomography; D011569:Psychiatric Status Rating Scales; D011903:Raphe Nuclei / Q000378:metabolism*; D050486:Serotonin Plasma Membrane Transport Proteins / Q000378:metabolism*; D014018:Tissue Distribution; D015854:Up-Regulation
chemical_list: D001596:Benzylamines; D002250:Carbon Radioisotopes; C420885:N,N-dimethyl-2-(2-amino-4-cyanophenylthio)benzylamine; D050486:Serotonin Plasma Membrane Transport Proteins