Impulsive choice and response in dopamine agonist-related impulse control behaviors.
BACKGROUND
Dopaminergic medication-related impulse control disorders (ICDs) such as pathological gambling and compulsive shopping have been reported in Parkinson's disease (PD).


OBJECTIVE
We hypothesized that dopamine agonists (DAs) would be associated with greater impulsive choice or greater discounting of delayed rewards in PD patients with ICDs (PDI).


METHODS
Fourteen PDI patients, 14 PD controls without ICDs, and 16 medication-free matched normal controls were tested on the Experiential Discounting Task (EDT), a feedback-based intertemporal choice task, spatial working memory, and attentional set shifting. The EDT was used to assess choice impulsivity (hyperbolic K value), reaction time (RT), and decision conflict RT (the RT difference between high conflict and low conflict choices). PDI patients and PD controls were tested on and off DA.


RESULTS
On the EDT, there was a group by medication interaction effect [F(1,26) = 5.62; p = 0.03] with pairwise analyses demonstrating that DA status was associated with increased impulsive choice in PDI patients (p = 0.02) but not in PD controls (p = 0.37). PDI patients also had faster RT compared to PD controls [F(1,26) = 7.51, p = 0.01]. DA status was associated with shorter RT [F(3,24) = 8.39, p = 0.001] and decision conflict RT [F(1,26) = 6.16, p = 0.02] in PDI patients but not in PD controls. There were no correlations between different measures of impulsivity. PDI patients on DA had greater spatial working memory impairments compared to PD controls on DA (t = 2.13, df = 26, p = 0.04).


CONCLUSIONS
Greater impulsive choice, faster RT, faster decision conflict RT, and executive dysfunction may contribute to ICDs in PD.
National Institutes of Health, 10 Center Drive, Bldg 10/Rm 7D37, Bethesda, MD 20892-1428, USA. voonv@ninds.nih.gov
Valerie
V
Voon
Brady
B
Reynolds
Christina
C
Brezing
Cecile
C
Gallea
Meliha
M
Skaljic
Vindhya
V
Ekanayake
Hubert
H
Fernandez
Marc N
MN
Potenza
Raymond J
RJ
Dolan
Mark
M
Hallett
D000328:Adult; D000368:Aged; D001288:Attention / Q000187:drug effects; D016022:Case-Control Studies; D003192:Compulsive Behavior / Q000150:complications / Q000209:etiology*; D007174:Disruptive, Impulse Control, and Conduct Disorders / Q000150:complications / Q000209:etiology*; D018491:Dopamine Agonists / Q000009:adverse effects* / Q000627:therapeutic use; D005260:Female; D005715:Gambling / Q000523:psychology; D006801:Humans; D008297:Male; D008569:Memory Disorders / Q000209:etiology; D008875:Middle Aged; D010300:Parkinson Disease / Q000150:complications / Q000188:drug therapy*; D011930:Reaction Time / Q000187:drug effects; D012718:Set, Psychology; D013647:Task Performance and Analysis
D018491:Dopamine Agonists