Predictors of neuropsychological effort test performance in schizophrenia

Abstract

There is some evidence that insufficient effort may be common in schizophrenia, posing significant threats to the validity of neuropsychological test results. Low effort may account for a significant proportion of variance in neuropsychological test scores and the generalized cognitive deficit that characterizes the disorder. The current study evaluated clinical predictors of insufficient effort in schizophrenia using an embedded effort measure, the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) Effort Index (EI). Participants were 330 patients meeting DSM-IV-TR criteria for schizophrenia, schizoaffective disorder, or another psychotic disorder who received a battery of neuropsychological tests, including: Wechsler Test of Adult Reading (WTAR), Wechsler Abbreviated Scale of Intelligence (WASI), and RBANS. Clinical assessments designed to measure functional outcome, symptoms, and premorbid adjustment were also obtained. Results indicated that 9.4% of patients failed the EI. Patients who failed had lower full-scale, verbal, and performance IQ, as well as poorer performance on RBANS domains not included in the EI (immediate memory, language, and visuospatial/construction). Patients who failed the EI also displayed poorer community-based vocational outcome, greater likelihood of having “deficit schizophrenia” (i.e., primary and enduring negative symptoms), and increased severity of positive symptoms. Regression analyses revealed that insufficient effort was most significantly predicted by a combination of low IQ, negative symptoms, and positive symptoms. Findings suggest that although insufficient effort may be relatively uncommon in schizophrenia, it is associated with important clinical outcomes. The RBANS EI may be a useful tool in evaluating insufficient effort in schizophrenia.

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

“…Use of multiple measurements increases validity of these determinations, as is typically done when using free-standing effort measures like the Word Memory test that include several subscales to determine effort test failure. The 16.1% two-test failure rate is comparable to the majority of prior studies examining cognitive effort in SZ (Arnold et al, 2005;Avery et al, 2009;Back et al, 1996;Duncan, 2005;Egeland et al, 2003;Gierok et al, 2005;Moore et al, 2013;Morra et al, 2015;Pivovarova et al, 2009;Schroeder and Marshall, 2011), which suggests that the majority of outpatients with a psychotic disorder put forth adequate effort during neuropsychological testing conducted in the context of a research study. The finding that 32.1% of SZ failed at least 1 effort test calls into question what the true rate of effort test failure is in SZ.…”

“…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).…”