title: Intertemporal choice in Parkinson's disease and restless legs syndrome.
abstract: BACKGROUND
  Impulse control disorders in Parkinson's disease are a potential consequence of dopaminergic therapy. Impulse control problems might be revealed by intertemporal choice tasks which entail to forgo an immediately available reward in favor of a larger but later reward. The steepness of the discounting curve can be quantified by the parameter k.
  
  
  METHODS
  Participants (37 Parkinson patients [13 de novo, 24 medicated], 24 patients with restless legs syndrome, and 22 controls) were offered 54 choices between immediate smaller rewards and delayed larger and the k value was estimated from the participants' responses. Participants had the chance of winning one of their decisions. None of the participants had impulse control disorders.
  
  
  RESULTS
  Unmedicated Parkinson patients had a higher discounting rate than controls and medicated patients with restless legs syndrome. The k values of medicated Parkinson patients and patients with restless legs syndrome did not differ from those of controls. No correlation was found between the k value and the dopamine agonist dose.
  
  
  CONCLUSIONS
  Impulsive decision making in patients with Parkinson's disease may occur as part of the disease rather than as a consequence of dopamine agonist therapy.
authors.affiliation: Department of Neurology, University of Lübeck, Lübeck, Germany.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Al-Khaled
authors.affiliation: Department of Neurology, University of Lübeck, Lübeck, Germany; Institute of Psychology II, University of Lübeck, Lübeck, Germany.
authors.forename: Marcus
authors.initials: M
authors.lastname: Heldmann
authors.affiliation: Department of Neurology, University of Lübeck, Lübeck, Germany.
authors.forename: Inga
authors.initials: I
authors.lastname: Bolstorff
authors.affiliation: Department of Neurology, Westküstenklinikum Heide, Heide, Germany.
authors.forename: Johann
authors.initials: J
authors.lastname: Hagenah
authors.affiliation: Department of Neurology, University of Lübeck, Lübeck, Germany; Institute of Psychology II, University of Lübeck, Lübeck, Germany. Electronic address: Thomas.muente@neuro.uni-luebeck.de.
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Münte
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D065786:Delay Discounting / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000503:physiopathology*; D012148:Restless Legs Syndrome / Q000503:physiopathology*
keywords: Delay discounting; Dopamine agonist; Impulse control disorder; L-Dopa; Parkinson disease; Pathological gambling; Restless legs syndrome