title: Serotonergic loss in motor circuitries correlates with severity of action-postural tremor in PD.
abstract: OBJECTIVE
  The underlying pathophysiology of tremor in Parkinson disease (PD) is unclear; however, it is known that tremor does not appear to be as responsive to dopaminergic medication as bradykinesia or rigidity. It is suggested that serotonergic dysfunction could have a role in tremor development.
  
  
  METHODS
  Using (11)C-DASB PET, a marker of serotonin transporter binding, and clinical observations, we have investigated function of serotonergic terminals in 12 patients with tremor-predominant and 12 with akinetic-rigid PD. Findings were compared with those of 12 healthy controls.
  
  
  RESULTS
  Reductions of (11)C-DASB in caudate, putamen, and raphe nuclei significantly correlated with tremor severity on posture and action, but not with resting tremor. The tremor-predominant group also showed reductions of (11)C-DASB in other regions involved in motor circuitry, including the thalamus and Brodmann areas 4 and 10.
  
  
  CONCLUSIONS
  Our findings support a role for serotonergic dysfunction in motor circuitries in the generation of postural tremor in PD.
authors.affiliation: Department of Medicine, Division of Brain Sciences, Hammersmith Hospital, Imperial College London, UK.
authors.forename: Clare
authors.initials: C
authors.lastname: Loane
authors.forename: Kit
authors.initials: K
authors.lastname: Wu
authors.forename: Peter
authors.initials: P
authors.lastname: Bain
authors.forename: David J
authors.initials: DJ
authors.lastname: Brooks
authors.forename: Paola
authors.initials: P
authors.lastname: Piccini
authors.forename: Marios
authors.initials: M
authors.lastname: Politis
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000503:physiopathology; D009415:Nerve Net / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000503:physiopathology; D010300:Parkinson Disease / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000503:physiopathology; D049268:Positron-Emission Tomography / Q000379:methods; D050486:Serotonin Plasma Membrane Transport Proteins / Q000378:metabolism* / Q000502:physiology; D012720:Severity of Illness Index; D014202:Tremor / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000503:physiopathology
chemical_list: D050486:Serotonin Plasma Membrane Transport Proteins