Elsevier

Biological Psychiatry

Volume 74, Issue 2, 15 July 2013, Pages 130-136
Biological Psychiatry

Archival Report
Negative Symptoms of Schizophrenia Are Associated with Abnormal Effort-Cost Computations

https://doi.org/10.1016/j.biopsych.2012.12.022Get rights and content

Background

Decision-making studies show that response selection is influenced by the “effort cost” associated with response alternatives. These effort-cost calculations seem to be mediated by a distributed neural circuit including the anterior cingulate cortex and subcortical targets of dopamine neurons. On the basis of evidence of dysfunction in these systems in schizophrenia (SZ), we examined whether effort-cost computations were impaired in SZ patients and whether these deficits were associated with negative symptoms.

Methods

Effort-cost decision-making performance was evaluated in 44 patients with SZ and 36 demographically matched control subjects. Subjects performed a computerized task where they were presented with a series of 30 trials in which they could choose between making 20 button presses for $1 or 100 button presses for higher amounts (varying from $3 to $7 across trials). Probability of reward receipt was also manipulated to determine whether certain (100%) or uncertain (50%) reward affected effort-based decision-making.

Results

Patients were less likely than control subjects to select the high-effort response alternative during the 100% probability condition, particularly when the value payoff was highest (i.e., $6 and $7). Patients were also less likely to select the high-effort option on trials after reward in the 50% probability condition. Furthermore, these impairments in effort-cost computations were greatest among patients with elevated negative symptoms. There was no association with haloperidol equivalent dosage.

Conclusions

The motivational impairments of SZ might be associated with abnormalities in estimating the “cost” of effortful behavior. This increased effort cost might undermine volition.

Section snippets

Participants

Forty-four individuals (42 outpatients, 2 inpatients) meeting DSM-IV (27) criteria for SZ (n = 36) or schizoaffective disorder (n = 8, none in mood episode at time of testing) and 36 healthy control subjects (CN) participated in the study. Patient and control groups did not significantly differ on age, parental education, gender, or ethnicity (Table 1). All patients were taking stable doses of medication for at least 4 weeks at the time of testing and were considered to be clinically stable by

Selection of Effortful Alternative in Relation to Value

Panels A and B of Figure 2 present the proportion of effortful response alternative selections as a function of potential gain value ($3–$7). A 2 Group (SZ vs. CN)×2 Probability (50% vs. 100%)×5 Value ($3, $4, $5, $6, $7) repeated-measures analysis of variance (ANOVA) indicated significant within-subjects effects of probability [F1,78 = 120.6, p<.01] and value [F4,78 = 61.90, p<.001]. However, the between-subjects effect was nonsignificant [F1,78 = 1.12, p = .29]. These analyses indicate that,

Discussion

These data suggest that negative symptoms are associated with abnormalities in effort-cost calculations. Patients with higher levels of negative symptoms were less willing to increase effort for higher levels of reward and were also less responsive to the receipt of an uncertain reward in motivating subsequent effortful behavior. This alteration in decision making was accompanied by more general evidence of reduced behavioral activation as seen in decreased response vigor in both high- and

References (36)

  • Kraepelin E (1919): Dementia Praecox and Paraphrenia. Amsterdam:...
  • A.S. Cohen et al.

    Emotional experience in patients with schizophrenia revisited: Meta-analysis of laboratory studies

    Schizophr Bull

    (2010)
  • M. Oorschot et al.

    Emotional experience in negative symptoms of schizophrenia—no evidence for a generalized hedonic deficit

    Schizophr Bull

    (2013)
  • G.P. Strauss et al.

    A new perspective on anhedonia in schizophrenia

    Am J Psychiatry

    (2012)
  • J.M. Gold et al.

    Reward processing in schizophrenia: A deficit in the representation of value

    Schizophr Bull

    (2008)
  • J.M. Gold et al.

    Negative symptoms and the failure to represent the expected reward value of actions: Behavioral and computational modeling evidence

    Arch Gen Psychiatry

    (2012)
  • D.M. Barch et al.

    Goal representations and motivational drive in schizophrenia: The role of prefrontal-striatal interactions

    Schizophr Bull

    (2010)
  • E.A. Heerey et al.

    Patients with schizophrenia demonstrate dissociation between affective experience and motivated behavior

    J Abnorm Psychol

    (2007)
  • Cited by (0)

    View full text