title: Dopaminergic involvement in effort-based but not impulsive reward processing in smokers.
abstract: BACKGROUND
  A reduction in reward responsivity and an increase in temporal discounting of rewards are both evident in smokers during acute abstinence compared to satiation. However, it is not yet known whether these processes can be modulated pharmacologically in smokers, other than with nicotine or tobacco.
  
  
  METHODS
  A double-blind placebo controlled crossover design assessed the effects of 0.5 mg pramipexole, a dopamine D₂/D₃ agonist, in smokers following 2 h of abstinence. Reward responsivity was measured using an effort-based card sorting task. Temporal discounting of monetary reward was assessed using Area Under the Curve (AUC) analysis, and affective and subjective effects were indexed.
  
  
  RESULTS
  On placebo, smokers showed an equivalent speed of card sorting when a financial incentive was provided compared to when it was not. Conversely, more cards were sorted under rewarded compared to non-rewarded trials after pramipexole, indicating an improvement in reward responsivity. Temporal discounting of monetary reward was not affected by pramipexole. Drug treatment also decreased positive affect and increased drowsiness.
  
  
  CONCLUSIONS
  A single dose of pramipexole can enhance effort-based reward responsivity, but does not alter temporal discounting in smokers. These findings highlight pharmacological correlates of reward processing deficits in nicotine dependence and offer potential targets for their treatment.
authors.affiliation: Clinical Psychopharmacology Unit, University College London, London WC1E 6BT, United Kingdom. tom.freeman@ucl.ac.uk
authors.forename: Tom P
authors.initials: TP
authors.lastname: Freeman
authors.forename: Celia J A
authors.initials: CJ
authors.lastname: Morgan
authors.forename: Brigitta
authors.initials: B
authors.lastname: Brandner
authors.forename: Basil
authors.initials: B
authors.lastname: Almahdi
authors.forename: H Valerie
authors.initials: HV
authors.lastname: Curran
mesh_terms: D000328:Adult; D052160:Benzothiazoles / Q000494:pharmacology / Q000627:therapeutic use; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007175:Impulsive Behavior / Q000188:drug therapy / Q000523:psychology*; D008297:Male; D000077487:Pramipexole; D011597:Psychomotor Performance / Q000187:drug effects / Q000502:physiology*; D017447:Receptors, Dopamine D1 / Q000819:agonists* / Q000502:physiology; D017448:Receptors, Dopamine D2 / Q000819:agonists* / Q000502:physiology; D012201:Reward; D012907:Smoking / Q000188:drug therapy / Q000523:psychology*; D016540:Smoking Cessation / Q000523:psychology; D013997:Time Factors; D055815:Young Adult
chemical_list: D052160:Benzothiazoles; C581293:DRD2 protein, human; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D000077487:Pramipexole