title: Incentive motivation deficits in schizophrenia reflect effort computation impairments during cost-benefit decision-making.
abstract: BACKGROUND
  Motivational impairments are a core feature of schizophrenia and although there are numerous reports studying this feature using clinical rating scales, objective behavioural assessments are lacking. Here, we use a translational paradigm to measure incentive motivation in individuals with schizophrenia.
  
  
  METHODS
  Sixteen stable outpatients with schizophrenia and sixteen matched healthy controls completed a modified version of the Effort Expenditure for Rewards Task that accounts for differences in motoric ability. Briefly, subjects were presented with a series of trials where they may choose to expend a greater amount of effort for a larger monetary reward versus less effort for a smaller reward. Additionally, the probability of receiving money for a given trial was varied at 12%, 50% and 88%. Clinical and other reward-related variables were also evaluated.
  
  
  RESULTS
  Patients opted to expend greater effort significantly less than controls for trials of high, but uncertain (i.e. 50% and 88% probability) incentive value, which was related to amotivation and neurocognitive deficits. Other abnormalities were also noted but were related to different clinical variables such as impulsivity (low reward and 12% probability). These motivational deficits were not due to group differences in reward learning, reward valuation or hedonic capacity.
  
  
  CONCLUSIONS
  Our findings offer novel support for incentive motivation deficits in schizophrenia. Clinical amotivation is associated with impairments in the computation of effort during cost-benefit decision-making. This objective translational paradigm may guide future investigations of the neural circuitry underlying these motivational impairments.
authors.affiliation: Schizophrenia Division, Centre for Addiction and Mental Health, 250 College Street, Toronto, ON, Canada M5T 1R8; Institute of Medical Science, University of Toronto, Toronto, ON, Canada. Electronic address: gagan.fervaha@utoronto.ca.
authors.forename: Gagan
authors.initials: G
authors.lastname: Fervaha
authors.forename: Ariel
authors.initials: A
authors.lastname: Graff-Guerrero
authors.forename: Konstantine K
authors.initials: KK
authors.lastname: Zakzanis
authors.forename: George
authors.initials: G
authors.lastname: Foussias
authors.forename: Ofer
authors.initials: O
authors.lastname: Agid
authors.forename: Gary
authors.initials: G
authors.lastname: Remington
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D003362:Cost-Benefit Analysis; D003657:Decision Making / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D019964:Mood Disorders / Q000175:diagnosis / Q000209:etiology*; D009042:Motivation / Q000502:physiology*; D011336:Probability; D011569:Psychiatric Status Rating Scales; D012559:Schizophrenia / Q000150:complications*; D012565:Schizophrenic Psychology; D018709:Statistics, Nonparametric; D055815:Young Adult
keywords: Apathy; Cost-benefit; Decision-making; Effort; Incentive motivation; Schizophrenia