The role of low cognitive effort and negative symptoms in neuropsychological impairment in schizophrenia.

Abstract

Objective Two experiments were conducted to examine whether insufficient effort, negative symptoms (e.g., avolition, anhedonia), and psychological variables (e.g., anhedonia and perception of low cognitive resources) predict generalized neurocognitive impairment in individuals with schizophrenia (SZ). Method In Experiment 1, participants included 97 individuals with SZ and 63 healthy controls (CN) who completed the Victoria Symptom Validity Test (VSVT), the MATRICS Consensus Cognitive Battery (MCCB), and self-report anhedonia questionnaires. In Experiment 2, participants included 46 individuals with SZ and 33 CN who completed Green’s Word Memory Test (WMT), the MCCB, and self-reports of anhedonia, defeatist performance beliefs, and negative expectancy appraisals. Results Results indicated that a low proportion of individuals with SZ failed effort testing (1.0% Experiment 1; 15.2% Experiment 2); however, global neurocognitive impairment was significantly predicted by low effort and negative symptoms. Conclusions Findings indicate that low effort does not threaten the validity of neuropsychological test results in the majority of individuals with schizophrenia; however, effort testing may be useful in SZ patients with severe negative symptoms who may be more likely to put forth insufficient effort due to motivational problems. Although the base rate of failure is relatively low, it may be beneficial to screen for insufficient effort in SZ and exclude individuals who fail effort testing from pharmacological or cognitive remediation trials.

The evaluation of insufficient cognitive effort in schizophrenia in light of low IQ scores

“…Thus, it may be that high rates of effort test failure are quite rare in SZ, only occurring in the most symptomatically severe and functionally impaired subset of patients. Similar to prior studies, the combination of insufficient effort and negative symptoms predicted a substantial proportion of variance in global neuropsychological test scores (27% in the current sample) (Avery et al, 2009;Gorissen et al, 2005;Morra et al, 2015;Strauss et al, 2015). However, positive symptoms were not a significant predictor.…”

“…Based on prior studies, it was hypothesized that a minority of SZ patients (approximately 15e25%) would fall below established effort cut-off scores (Duncan, 2005;Egeland et al, 2003;Gierok et al, 2005;Hunt et al, 2014;Moore et al, 2013;Schroeder and Marshall, 2011)and that insufficient effort would be predicted by low IQ and greater severity of negative symptoms (Avery et al, 2009;Gorissen et al, 2005;Morra et al, 2015;Strauss et al, 2015). Additionally, consistent with the notion that low effort contributes to the generalized neurocognitive deficit, we predicted that insufficient effort would account for a significant proportion of variance in neuropsychological performance on tests not used to index insufficient effort.…”

“…The majority of studies have indicated that approximately 15e25% of SZ patients fall below standard clinical cut-offs for low effort (Avery et al, 2009;Back et al, 1996;Duncan, 2005;Egeland et al, 2003;Gierok et al, 2005;Hunt et al, 2014;Moore et al, 2013;Pivovarova et al, 2009;Schroeder and Marshall, 2011) although a few studies report failure rates as high as 60%e72% (Gorissen et al, 2005;Hunt et al, 2014). Several factors may contribute to discrepant rates of effort test failure observed across studies, including inpatient versus outpatient status, level of personal and parental education, symptom severity, the sensitivity and specificity of effort tests administered, and whether the effort test used was embedded or freestanding (see Gorissen et al, 2005;Hunt et al, 2014;Morra et al, 2015;Strauss et al, 2015). Although the proportion of SZ patients failing effort tests may be inconsistent across studies, the ability of effort tests to predict neurocognitive impairment is reliable, with low effort accounting for approximately 25e35% of variance in global neuropsychological test scores (Avery et al, 2009;Gorissen et al, 2005;Morra et al, 2015;Strauss et al, 2015).…”

“…Several factors may contribute to discrepant rates of effort test failure observed across studies, including inpatient versus outpatient status, level of personal and parental education, symptom severity, the sensitivity and specificity of effort tests administered, and whether the effort test used was embedded or freestanding (see Gorissen et al, 2005;Hunt et al, 2014;Morra et al, 2015;Strauss et al, 2015). Although the proportion of SZ patients failing effort tests may be inconsistent across studies, the ability of effort tests to predict neurocognitive impairment is reliable, with low effort accounting for approximately 25e35% of variance in global neuropsychological test scores (Avery et al, 2009;Gorissen et al, 2005;Morra et al, 2015;Strauss et al, 2015). Thus, there is some evidence that insufficient effort contributes at least to some extent to the generalized neurocognitive deficit that characterizes SZ.…”

“…Participants therefore had no readily identifiable incentive to put forth suboptimal performance during testing. Instead, the most viable explanation seems to be that individuals with SZ fail effort tests due to motivational impairments that are core to the disease and affect approximately 1/3 of the SZ population (Ahmed et al, 2014;Foussias and Remington, 2010; Several studies now support this "motivational" interpretation, reporting that negative symptoms and psychological processes associated with negative symptoms (e.g., defeatist performance beliefs) are associated with effort test failure in SZ (Avery et al, 2009;Gorissen et al, 2005;Morra et al, 2015;Strauss et al, 2015).…”