title: Proficient motor impulse control in Parkinson disease patients with impulsive and compulsive behaviors.
abstract: BACKGROUND
  Parkinson disease (PD) patients treated with dopamine agonist therapy can develop maladaptive reward-driven behaviors, known as impulse control disorder (ICD). In this study, we assessed if ICD patients have evidence of motor-impulsivity.
  
  
  METHODS
  We used the stop-signal task in a cohort of patients with and without active symptoms of ICD to evaluate motor-impulsivity. Of those with PD, 12 were diagnosed with ICD symptoms (PD-ICD) and were assessed before clinical reduction of dopamine agonist medication; 12 were without symptoms of ICD [PD-control] and taking equivalent dosages of dopamine agonist. Levodopa, if present, was maintained in both settings. Groups were similar in age, duration, and severity of motor symptoms, levodopa co-therapy, and total levodopa daily dose. All were tested in the dopamine agonist medicated and acutely withdrawn (24 h) state, in a counterbalanced manner. Primary outcome measures were mean reaction time to correct go trials (go reaction time), and mean stop-signal reaction time (SSRT).
  
  
  RESULTS
  ICD patients produce faster SSRT than both Healthy Controls, and PD-Controls. Faster SSRT in ICD patients is apparent in both dopamine agonist medication states. Also, we show unique dopamine medication effects on Go Reaction time (GoRT). In dopamine agonist monotherapy patients, dopamine agonist administration speeds GoRT. Conversely, in those with levodopa co-therapy, dopamine agonist administration slows.
  
  
  CONCLUSIONS
  PD patients with active ICD symptoms are significantly faster at stopping initiated motor actions, and this is not altered by acute dopamine agonist withdrawal. In addition, the effect of dopamine agonist on GoRT is strongly influenced by the presence or absence of levodopa, even though levodopa co-therapy does not appear to influence SSRT. We discuss these findings as they pertain to the multifaceted definition of 'impulsivity,' the lack of evidence for motor-impulsivity in PD-ICD, and dopamine effects on motor-control in PD.
authors.affiliation: Department of Neurology, Vanderbilt University, Nashville, TN, United States. Electronic address: daniel.claassen@vanderbilt.edu.
authors.forename: Daniel O
authors.initials: DO
authors.lastname: Claassen
authors.affiliation: Department of Psychology, University of Amsterdam, Netherlands.
authors.forename: Wery P M
authors.initials: WP
authors.lastname: van den Wildenberg
authors.affiliation: Department of Neurology, University of Virginia, Charlottesville, VA, United States.
authors.forename: Madaline B
authors.initials: MB
authors.lastname: Harrison
authors.affiliation: Department of Neurology, Vanderbilt University, Nashville, TN, United States.
authors.forename: Nelleke C
authors.initials: NC
authors.lastname: van Wouwe
authors.affiliation: Department of Neurology, Vanderbilt University, Nashville, TN, United States.
authors.forename: Kristen
authors.initials: K
authors.lastname: Kanoff
authors.affiliation: Department of Neurosurgery, Vanderbilt University, Nashville, TN, United States.
authors.forename: Joseph S
authors.initials: JS
authors.lastname: Neimat
authors.affiliation: Department of Neurology, Vanderbilt University, Nashville, TN, United States.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Wylie
mesh_terms: D000978:Antiparkinson Agents / Q000627:therapeutic use; D016022:Case-Control Studies; D007174:Disruptive, Impulse Control, and Conduct Disorders / Q000150:complications / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007980:Levodopa / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000150:complications / Q000188:drug therapy / Q000503:physiopathology*; D011930:Reaction Time
chemical_list: D000978:Antiparkinson Agents; D007980:Levodopa
keywords: Dopamine agonist; Impulse control disorder; Inhibition; Motor impulsivity; Parkinson disease; Reaction time