title: Impulse control disorders in Parkinson's disease: decreased striatal dopamine transporter levels.
abstract: OBJECTIVE
  Impulse control disorders are commonly associated with dopaminergic therapy in Parkinson's disease (PD). PD patients with impulse control disorders demonstrate enhanced dopamine release to conditioned cues and a gambling task on [(11)C]raclopride positron emission tomography (PET) imaging and enhanced ventral striatal activity to reward on functional MRI. We compared PD patients with impulse control disorders and age-matched and gender-matched controls without impulse control disorders using [(123)I]FP-CIT (2β-carbomethoxy-3β-(4-iodophenyl)tropane) single photon emission computed tomography (SPECT), to assess striatal dopamine transporter (DAT) density.
  
  
  METHODS
  The [(123)I]FP-CIT binding data in the striatum were compared between 15 PD patients with and 15 without impulse control disorders using independent t tests.
  
  
  RESULTS
  Those with impulse control disorders showed significantly lower DAT binding in the right striatum with a trend in the left (right: F(1,24)=5.93, p=0.02; left: F(1,24)=3.75, p=0.07) compared to controls.
  
  
  CONCLUSIONS
  Our findings suggest that greater dopaminergic striatal activity in PD patients with impulse control disorders may be partly related to decreased uptake and clearance of dopamine from the synaptic cleft. Whether these findings are related to state or trait effects is not known. These findings dovetail with reports of lower DAT levels secondary to the effects of methamphetamine and alcohol. Although any regulation of DAT by antiparkinsonian medication appears to be modest, PD patients with impulse control disorders may be differentially sensitive to regulatory mechanisms of DAT expression by dopaminergic medications.
authors.affiliation: Department of Psychiatry, University of Cambridge, , Cambridge, UK.
authors.forename: Valerie
authors.initials: V
authors.lastname: Voon
authors.forename: Alexandra
authors.initials: A
authors.lastname: Rizos
authors.forename: Riddhika
authors.initials: R
authors.lastname: Chakravartty
authors.forename: Nicola
authors.initials: N
authors.lastname: Mulholland
authors.forename: Stephanie
authors.initials: S
authors.lastname: Robinson
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Howell
authors.forename: Neil
authors.initials: N
authors.lastname: Harrison
authors.forename: Gill
authors.initials: G
authors.lastname: Vivian
authors.forename: K
authors.initials: K
authors.lastname: Ray Chaudhuri
mesh_terms: D016022:Case-Control Studies; D003342:Corpus Striatum / Q000000981:diagnostic imaging / Q000378:metabolism*; D007174:Disruptive, Impulse Control, and Conduct Disorders / Q000150:complications* / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000523:psychology*; D050483:Dopamine Plasma Membrane Transport Proteins / Q000378:metabolism*; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000150:complications* / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000523:psychology*; D011877:Radionuclide Imaging; D014326:Tropanes
chemical_list: D050483:Dopamine Plasma Membrane Transport Proteins; D007457:Iodine Radioisotopes; D014326:Tropanes; C087552:2-carbomethoxy-8-(3-fluoropropyl)-3-(4-iodophenyl)tropane
keywords: BEHAVIOURAL DISORDER; FUNCTIONAL IMAGING; MOVEMENT DISORDERS; NEUROPSYCHIATRY; SPECT
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