Brain activity and connectivity differences in reward value discrimination during effort computation in schizophrenia

Effort-Cost Decision-making Among Individuals With Schizophrenia: A Systematic Review and Meta-analysis

Importance

Motivational impairments in schizophrenia are by definition associated with poor outcome. It is postulated that the reduction of goal-directed behavior arises from abnormal trade-offs between rewards and efforts.

Objective

To examine whether schizophrenia is associated with impairments in effort-cost decision-making.

Data Sources

For this systematic review and meta-analysis, the PubMed, ScienceDirect, PsycINFO, Embase, and ClinicalTrials.gov databases were searched from inception to July 2022 for studies that investigated effort-cost decision-making in schizophrenia. Search terms included effort, cost, and schizophrenia.

Study Selection

Consensual criteria for inclusion were peer-reviewed studies published in English that used a computerized effort-cost decision-making behavioral paradigm and compared individuals with schizophrenia with control individuals.

Data Extraction and Synthesis

The Preferred Reporting Items for Systematic Reviews and Meta-analyses reporting guideline was used for abstracting data. Data were extracted independently by 2 authors and then pooled using random-effects sizes and bayesian approaches.

Main Outcomes and Measures

The main outcomes were performance on effort-cost decision-making tasks requiring an effort-reward trade-off, measured by Hedges g effect size. Effects of moderators were tested with meta-regressions and subgroup analyses.

Results

Twenty studies involving 1503 participants were included: 837 individuals with schizophrenia (541 [64.6%] male; mean [SD] age, 35.89 [6.70] years) and 666 control individuals without schizophrenia (360 [54.1%] male; mean [SD] age, 34.16 [5.92] years). Participants with schizophrenia had significantly reduced willingness to expend effort for rewards compared with controls (k = 20; effect size, 0.43; 95% CI, 0.30-0.56; P < .001; I2 = 33.1%; Q test P = .08). The magnitude of the deficit was significantly greater for high-reward trials. The severity of negative symptoms was negatively associated with effort-cost decision-making (k = 8; effect size, -0.33; 95% CI, -0.50 to -0.15; P < .001), while participants with a high number of negative symptoms had a significantly larger impairment in effort-cost decision-making (k = 5; effect size, 0.47; 95% CI, 0.10-0.84; P = .01).

Conclusions and Relevance

In this systematic review and meta-analysis, schizophrenia was associated with deficits in effort allocation as indexed by effort-cost decision-making tasks. Understanding the cognitive and neurobiological mechanisms driving effort allocation impairments may assist in developing novel interventions.

Neural Circuitry of Salience and Reward Processing in Psychosis

The processing of salient and rewarding stimuli is integral to engaging our attention, stimulating anticipation for future events, and driving goal-directed behaviors. Widespread impairments in these processes are observed in psychosis, which may be associated with worse functional outcomes or mechanistically linked to the development of symptoms. Here, we summarize the current knowledge of behavioral and functional neuroimaging in salience, prediction error, and reward. Although each is a specific process, they are situated in multiple feedback and feedforward systems integral to decision making and cognition more generally. We argue that the origin of salience and reward processing dysfunctions may be centered in the subcortex during the earliest stages of psychosis, with cortical abnormalities being initially more spared but becoming more prominent in established psychotic illness/schizophrenia. The neural circuits underpinning salience and reward processing may provide targets for delaying or preventing progressive behavioral and neurobiological decline.

Associations Between Negative Symptoms and Effort Discounting in Patients With Schizophrenia and Major Depressive Disorder

Deficits in goal-directed decision making and motivation are hallmark characteristics of several neuropsychiatric disorders, including schizophrenia (SZ) and major depressive disorder (MDD). Studies using effort-based decision-making tasks have shown that both patients with SZ and MDD invest less physical effort in order to obtain rewards. However, how these motivational deficits relate to clinically assessed symptom dimensions such as apathy remains controversial. Using a grip-strength-based effort discounting task we assessed effort-based decision-making behavior in healthy controls (HC) (N = 18), patients with SZ (N = 42), and MDD (N = 44). We then investigated how effort discounting relates to different symptom dimensions. There were no differences in effort discounting between HC participants and patients with SZ or MDD. In addition, we did not observe a correlation between effort discounting and negative symptoms (NS) in patients with SZ or MDD. In conclusion, the current study does not support an association between effort discounting and NS in SZ or MDD. Further studies are needed to investigate effort discounting and its relation to psychopathological dimensions across different neuropsychiatric disorders.