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

Abstract

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.

Apathy in schizophrenia as a deficit in the generation of options for action.

“…In particular, they are in line with previously reported dysfunctional cost-benefit decision-making in schizophrenia (Fervaha, Graff-Guerrero, et al, 2013;Gold et al, 2013;Hartmann et al, in press). …”

“…Accumulating evidence suggests that among the two negative symptom factors, apathy is more strongly linked to functional outcome Strauss et al, 2013), thus emphasizing the need for a better understanding of apathy in schizophrenia to improve treatment.…”

Dissociable Contributions of Anterior Cingulate Cortex and Basolateral Amygdala on a Rodent Cost/Benefit Decision-Making Task of Cognitive Effort

“…The disturbances of effort-based decision making observed in a number of mental health populations (Gold et al, 2013;Treadway et al, 2012a) may therefore reflect underlying functional and connective changes to regions such as the amygdala and ACC. Dopamine function, which has long been implicated in willingness to expend effort (Salamone, 2009;Salamone et al, 2007;Treadway et al, 2012b), may also act on these regions to affect effortful decision making (Schweimer and Hauber, 2006;Schweimer et al, 2005), and thus its contribution to cognitive effort is currently under study.…”

“…Diminished motivation for such rewards can negatively impact an individual's quality of life, reaching clinical significance in a number of conditions including schizophrenia, depression, and attention-deficit/hyperactivity disorder (ADHD; Egeland et al, 2010;Gold et al, 2013;Hammar et al, 2011).…”

Ventral striatal hypoactivation is associated with apathy but not diminished expression in patients with schizophrenia

“…1,7,8 Apathy can be defined as reduction of motivation and goal-directed behaviour. 9,10 Several behavioural studies have shown that motivational impairments in schizophrenia are associated with dysfunctional processing of reward information in effort-based decision making, 11,12 reinforcement learning and during reward anticipation. 13,14 On the neural level, the ventral striatum appears to play an important role in coding incentive motivation 15,16 or wanting of a reward.…”