Predictors of neuropsychological effort test performance in schizophrenia

The use of performance validity tests among inpatient forensic monolingual Spanish-speakers

Performance validity tests (PVTs) are an integral part of neuropsychological assessments. Yet no studies have examined how Spanish-speaking forensic inpatients perform on PVTs, making it difficult to interpret these tests in this population. The present study examined archival data collected from monolingual Spanish-speaking forensic inpatients (n = 55; Mage = 49.6 years, SD = 12.0; 84.9% male; 93.5% diagnosed with a Psychotic Spectrum Disorder) to determine how this population performs on several PVTs. Most participants' scores on the Dot Counting Test (DCT; 82.2%; n = 45), Repeatable Battery for Assessment of Neuropsychological Status-Effort Index (RBANS EI; 84.4%; n = 33), and Test of Memory Malingering (TOMM; 79.1%; n = 43) were indicative of valid performance. Few participants, however, had Rey-15 Item Test (FIT) scores in the valid range (24.5% to 48.0%; Recall n = 50 and Combined n = 49, respectively); although FIT Recall specificity was improved when cutoff scores were lowered. Total years of education, but not other educational factors, were significantly associated with performance on PVTs (r = .33-.40, p = .01-.03). Study results suggest the DCT, TOMM, and RBANS EI may be more appropriate PVTs for Spanish-speaking forensic inpatients compared to the FIT.

Cognitive intraindividual variability, cognitive impairment and psychosocial functioning in first-episode psychosis patients

Cognitive intraindividual variability (IIV) refers to fluctuations in performance across tasks (i.e. dispersion) or in a single task on multiple occasions (i.e. inconsistency). Little is known about IIV in patients with first-episode psychosis (FEP). We aimed to explore the association between IIV and both global cognitive performance and psychosocial functioning in a sample of 103 FEP patients. Patients were recruited at discharge from the PEPsNa program, a FEP follow-up intervention program lasting 24 months. The Social and Occupational Functioning Scale (SOFAS) and the Cognitive Assessment Interview (CAI-Sp) were employed for assessing psychosocial functioning. Cognitive assessments were performed using the MATRICS Cognitive Assessment Battery (MCCB), and the variability in the cognitive functions assessed with the MCCB was used to calculate the IIV. Significant correlations were obtained between IIV and global MCCB scores, the CAI-Sp and the SOFAS. We found significant differences in psychosocial functioning and cognitive performance between patients with high and low IIV. A higher IIV in FEP patients was related both to worse psychosocial functioning and worse global cognitive performance. Unlike global cognitive performance, IIV was not related to clinical characteristics, suggesting that it could be an indicator of cognitive impairment even in the absence of global impairment.

Age of Onset Moderates the Association between Total Antioxidant Capacity and Cognitive Deficits in Patients with Drug-Naïve Schizophrenia

Schizophrenia patients with an earlier age of onset have been found to have more serious negative symptoms and cognitive deficits. Oxidative stress is thought to be implicated in cognitive impairment in schizophrenia. Total antioxidant capacity (TAOC) is an essential indicator of oxidative stress. However, the association between age of onset, TAOC, and cognitive performance in schizophrenia remains unexplored. In this study, 201 patients (age: 26.5 ± 9.6 years; male: 53.2%) with drug-naïve schizophrenia were recruited. Clinical symptoms were evaluated using the Positive and Negative Syndrome Scale (PANSS). Cognitive functioning was assessed using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Plasma TAOC levels were analyzed using established procedures. Results showed that early-onset (EO) patients had higher TAOC levels, more severe negative symptoms and performed worse on visuospatial/constructional, language and RBANS total scores than non-EO patients. After Bonferroni correction, only non-EO patients showed a significant inverse relationship between TAOC levels and RBANS language, attention, and total scores. Our findings suggest that an early/late age of onset may be correlated with psychopathological symptoms, cognitive impairment and oxidative responses in schizophrenia. Furthermore, the age of onset may moderate the relationship between TAOC and cognitive function in patients with schizophrenia. These findings suggest that improving oxidative stress status in non-EO schizophrenia patients may enhance their cognitive function.

Examining the repeatable battery for the assessment of neuropsychological status validity indices in people with schizophrenia spectrum disorders

Objective: We examined the frequency of possible invalid test scores on the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) in patients with schizophrenia spectrum disorders, and whether there was an association between scores on the embedded RBANS performance validity tests (PVTs) and self-reported symptoms of apathy as measured by the Initiate Scale of the Behavior Rating Inventory of Executive Function-Adult Version (BRIEF-A). Methods: Participants included 250 patients (M = 24.4 years-old, SD = 5.7) with schizophrenia spectrum disorders. Base rates of RBANS Effort Index (EI), Effort Scale (ES), and Performance Validity Index (PVI) test scores were computed. Spearman correlations were used to examine the associations between the RBANS PVTs, the RBANS Index scores, and the BRIEF-A Initiate Scale. Regression analyses were used to investigate how well the RBANS PVTs predicted scores on the BRIEF-A Initiate Scale. Results: The frequency of invalid scores on the EI (>3) and the PVI (<42) in participants with schizophrenia spectrum disorders was 6%. The frequency of invalid ES scores (<12) was 28% in the patients compared to 15% in the U.S. standardization sample. There was a small significant correlation between the EI and the BRIEF-A Initiate Scale (rho=.158, p<.05). Conclusions: The rates of invalid scores were similar to previously published studies. Invalid scores on the BRIEF-A were uncommon. Apathy measured with the BRIEF-A Initiate Scale was not associated with performance on the RBANS validity measures or with measures of cognition.

Effectiveness of KarXT (xanomeline-trospium) for cognitive impairment in schizophrenia: post hoc analyses from a randomised, double-blind, placebo-controlled phase 2 study

The muscarinic receptor agonist xanomeline improved cognition in phase 2 trials in Alzheimer's disease and schizophrenia. We present data on the effect of KarXT (xanomeline-trospium) on cognition in schizophrenia from the 5-week, randomised, double-blind, placebo-controlled EMERGENT-1 trial (NCT03697252). Analyses included 125 patients with computerised Cogstate Brief Battery (CBB) subtest scores at baseline and endpoint. A post hoc subgroup analysis evaluated the effects of KarXT on cognitive performance in patients with or without clinically meaningful cognitive impairment at baseline, and a separate outlier analysis excluded patients with excessive intraindividual variability (IIV) across cognitive subdomains. ANCOVA models assessed treatment effects for completers and impairment subgroups, with or without removal of outliers. Sample-wide, cognitive improvement was numerically but not statistically greater with KarXT (n = 60) than placebo (n = 65), p = 0.16. However, post hoc analyses showed 65 patients did not exhibit clinically meaningful cognitive impairment at baseline, while eight patients had implausibly high IIV at one or both timepoints. Significant treatment effects were observed after removing outliers (KarXT n = 54, placebo n = 63; p = 0.04). Despite the small sample size, a robust (d = 0.50) and significant effect was observed among patients with cognitive impairment (KarXT n = 23, placebo n = 37; p = 0.03). These effects did not appear to be related to improvement in PANSS total scores (linear regression, R²= 0.03). Collectively, these findings suggest that KarXT may have a separable and meaningful impact on cognition, particularly among patients with cognitive impairment.

Differences of resting fMRI and cognitive function between drug-naïve bipolar disorder and schizophrenia

BACKGROUND

Bipolar disorder (BD) and schizophrenia (SC) have many similarities in clinical manifestations. The acute phase of BD has psychotic symptoms, while SC also has emotional symptoms during the onset, which suggests that there is some uncertainty in distinguishing BD and SC through clinical symptoms.

AIM

To explore the characteristics of brain functional activities and cognitive impairment between BD and SC.

METHODS

Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) test was performed on patients in drug-naïve BD and SC (50 subjects in each group), and resting-state functional magnetic resonance imaging (rs-fMRI) scanning was performed meanwhile. Rs-fMRI data were routinely preprocessed, and the value of the fractional amplitude of low-frequency fluctuation (fALFF) was calculated. Then each part of the scores of the RBANS and the characteristics of brain function activities were compared between the two groups. Finally used Pearson correlation to analyze the correlation between cognition and brain function.

RESULTS

(1) Compared with BD group, all parts of RBANS scores in SC group decreased; (2) The left inferior occipital gyrus (IOG, peak coordinates - 30, -87, -15; t = 4.78, voxel size = 31, Alphasim correction) and the right superior temporal gyrus (STG, peak coordinates 51, -12, 0; t = 5.08, voxel size = 17, AlphaSim correction) were the brain areas with significant difference in fALFF values between BD and SC. Compared with SC group, the fALFF values of the left IOG and the right STG in BD group were increased (p < 0.05); (3) Pearson correlation analysis showed that the visuospatial construction score was positively correlated with the fALFF values of the left IOG and the right STG (r_{left IOG} = 0.304, p = 0.003; r_{right STG} = 0.340, p = 0.001); The delayed memory (figure recall) score was positively correlated with the fALFF value of the left IOG (r_{left IOG} = 0.207, p = 0.044).

DISCUSSION

The cognitive impairment of SC was more serious than BD. The abnormal activities of the left IOG and the right STG may be the core brain region to distinguish BD and SC, and are closely related to cognitive impairment, which provide neuroimaging basis for clinical differential diagnosis and explore the pathological mechanism of cognitive impairment.

A Meta-Analysis of Neuropsychological Effort Test Performance in Psychotic Disorders

Psychotic disorders are characterized by a generalized neurocognitive deficit (i.e., performance 1.5 SD below controls across neuropsychological domains with no specific profile of differential deficits). A motivational account of the generalized neurocognitive deficit has been proposed, which attributes poor neuropsychological testing performance to low effort. However, findings are inconsistent regarding effort test failure rate in individuals with psychotic disorders across studies (0-72%), and moderators are unclear, making it difficult to know whether the motivational explanation is viable. To address these issues, a meta-analysis was performed on data from 2205 individuals with psychotic disorders across 19 studies with 24 independent effects. Effort failure rate was examined along with moderators of effort test type, forensic status, IQ, positive symptoms, negative symptoms, diagnosis, age, gender, education, and antipsychotic use. The pooled weighted effort test failure rate was 18% across studies and there was a moderate pooled association between effort failure rate and global neurocognitive performance (r = .57). IQ and education significantly moderated failure rate. Collectively, these findings suggest that a nontrivial proportion of individuals with a psychotic disorder fail effort testing, and failure rate is associated with global neuropsychological impairment. However, given that effort tests are not immune to the effects of IQ in psychotic disorders, these results cannot attest to the viability of the motivational account of the generalized neurocognitive deficit. Furthermore, the significant moderating effect of IQ and education on effort test performance suggests that effort tests have questionable validity in this population and should be interpreted with caution.

Performance Validity, Neurocognitive Disorder, and Post-concussion Symptom Reporting in Service Members with a History of Mild Traumatic Brain Injury

Objective

To examine the influence of different performance validity test (PVT) cutoffs on neuropsychological performance, post-concussion symptoms, and rates of neurocognitive disorder and postconcussional syndrome following mild traumatic brain injury (MTBI) in active duty service members.

Method

Participants were 164 service members (Age: M = 28.1 years [SD = 7.3]) evaluated on average 4.1 months (SD = 5.0) following injury. Participants were divided into three mutually exclusive groups using original and alternative cutoff scores on the Test of Memory Malingering (TOMM) and the Effort Index (EI) from the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS): (a) PVT-Pass, n = 85; (b) Alternative PVT-Fail, n = 53; and (c) Original PVT-Fail, n = 26. Participants also completed the Neurobehavioral Symptom Inventory.

Results

The PVT-Pass group performed better on cognitive testing and reported fewer symptoms than the two PVT-Fail groups. The Original PVT-Fail group performed more poorly on cognitive testing and reported more symptoms than the Alternative PVT-Fail group. Both PVT-Fail groups were more likely to meet DSM-5 Category A criteria for mild and major neurocognitive disorder and symptom reporting criteria for postconcussional syndrome than the PVT-Pass group. When alternative PVT cutoffs were used instead of original PVT cutoffs, the number of participants with valid data meeting cognitive testing criteria for neurocognitive disorder or postconcussional syndrome decreased dramatically.

Conclusion

PVT performance is significantly and meaningfully related to overall neuropsychological outcome. By using only original cutoffs, clinicians and researchers may miss people with invalid performances.

Psychometric limitations of the RBANS effort index in forensic inpatient populations

Although the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) is a widely studied and utilized screening measure with an Effort Index (EI), there is a minimal amount of data available regarding the utility of the EI for forensic inpatients. Specific concerns include the possibility that the published cutoffs would result in high false positive rates. The present study investigated this issue by comparing the validity of the RBANS EI with that of the Dot Counting Test (DCT) and Test of Memory Malingering (TOMM) in a forensic psychiatric setting (N = 117). Analyses indicated a positive association between RBANS EI categorizations (invalid or genuine responding) and the classifications made by the DCT and the TOMM. However, the false positive rate for the RBANS EI was found to be excessively high (17.95%), while the positive predictive value was below chance (44.74%). Additional psychometric properties for the RBANS EI in this population are reported in the article, including findings from a Receiver Operating Characteristic (ROC) analysis. Overall, the results suggest that caution is warranted, when utilizing the RBANS EI as a validity measure within a forensic inpatient psychiatric setting and more appropriate cutoffs are needed for this population.

What accounts for poor functioning in people with schizophrenia: a re-evaluation of the contributions of neurocognitive v. attitudinal and motivational factors

BACKGROUND

Neurocognitive deficits are often seen as core features of schizophrenia, and as primary determinants of poor functioning. Yet, our clinical observations suggest that individuals who score within the impaired range on standardized tests can reliably perform better in complex real-world situations, especially when performance is embedded within a positive socio-affective context.

METHODS

We analyzed literature on the influence of non-neurocognitive factors on test performance in order to clarify their contributions.

RESULTS

We identified seven non-neurocognitive factors that significantly contribute to neurocognitive test performance: avolition, dysfunctional attitudes, effort, stress, negative emotions, asociality, and disorganized symptoms. We then proposed an alternative model based on dysfunctional (e.g. defeatist) attitudes and their consequences for motivation and sustained task engagement. We demonstrated that these factors account for substantial variance in negative symptoms, neurocognitive test performance, and functional outcomes. We then demonstrated that recovery-oriented cognitive therapy - which is derived from this alternative model and primarily targets dysfunctional beliefs - has been successful in the treatment of low functioning individuals with schizophrenia.

CONCLUSION

The contributions of neurocognitive impairments to poor real-world functioning in people with schizophrenia may be overstated in the literature, and may even be limited relative to non-neurocognitive factors. We offer suggestions for further research to more precisely quantify the contributions of attitudinal/motivation v. neurocognitive factors in schizophrenia.

A meta-analysis of the accuracy of embedded performance validity indicators from the repeatable battery for the assessment of neuropsychological status

Objective: Meta-analyze the embedded performance validity tests of the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), emphasizing two topics: diagnostic accuracy and relationships with demographics. Method: Literature was identified through a review of PsycINFO, PubMed, and Google Scholar. Bivariate linear mixed models were used for diagnostic accuracy analyses. Random-effects analysis of correlations with demographic variables was also used for the Effort Index. Results: Diagnostic accuracy analyses utilized 12 studies of the Effort Index (EI; N = 1469) and 6 studies of the Effort Scale (ES; N = 854). The EI was found to have a sensitivity of .44 (95% CI: .28 - .62), specificity of .87 (95% CI: .78 - .93), and diagnostic odds ratio (DOR) of 5.41 (95% CI: 3.74 - 7.58). The ES produced a sensitivity of .67 (95% CI: .50 - .81), specificity of .72 (95% CI: .53 - .85), and DOR of 5.97 (95% CI: 1.70 - 15.30). Meta-analysis of correlations utilized 14 samples of the EI (N = 3781), but insufficient data were available for the ES. Correlations between the EI and age (r = .10, 95% CI: .05 - .16), education (r = -.11, 95% CI: -.18 to -.04), and the RBANS Total Scale (r = -.45, 95% CI: -.62 to -.24) were significant. These results appeared to be robust to publication bias. Conclusion: Results support use of the EI over the ES; however, the latter is comparatively less studied and did not have similar variability in reported cut-off scores. ES accuracy statistics were significantly predicted by sample variables, which may be related to its relatively fewer studies. Both measures should be used cautiously in the context of genuine cognitive impairment.

Relationship between effortful motivation and neurocognition in schizophrenia

Effortful motivation and reward valuation learning deficits are associated with negative symptoms and impaired cognition in schizophrenia (SZ) patients. Whereas clinical assessments of motivation and reward value typically rely upon clinician ratings or self-report scales, behavioral measures often confound these constructs. Simple reverse-translated behavioral tasks that independently quantify motivation and reward valuation-which could then be linked to cognition-may facilitate the development of pro-cognitive therapeutics by bridging the "preclinical-to-clinical" gap. This study determined whether novel behavioral measures of effortful motivation and reward valuation are associated with impaired cognition in SZ patients (n=36). Patients completed the Progressive Ratio Breakpoint task (PRBT; physical effort motivation) and the Probabilistic Learning Task (PLT; reward learning/valuation) in conjunction with the MATRICS Consensus Cognitive Battery (MCCB). SZ patients exhibited statistically significant deficits in global cognition and all individual MCCB subdomains. Significant correlations were observed between PRBT and MCCB global cognition (r=0.52), speed of processing (r=0.56) and attention vigilance (r=0.48) subdomains, but not with PLT or clinical symptoms. Results indicate that effort and reward learning deficits are dissociable targets that can improve our understanding of cognitive impairments associated among patients with SZ. More importantly, the results support the long-standing notion that the measurement of cognitive impairments in SZ is highly linked to a willingness to expend effort. The availability of a PRBT designed for use in both rodents and humans could improve our understanding of the nature of cognitive impairments in neuropsychiatric disorders and accelerate the development of novel pro-cognitive therapeutics.

Primary and persistent negative symptoms: Concepts, assessments and neurobiological bases

Primary and persistent negative symptoms (PPNS) represent an unmet need in the care of people with schizophrenia. They have an unfavourable impact on real-life functioning and do not respond to available treatments. Underlying etiopathogenetic mechanisms of PPNS are still unknown. The presence of primary and enduring negative symptoms characterizes deficit schizophrenia (DS), proposed as a separate disease entity with respect to non-deficit schizophrenia (NDS). More recently, to reduce the heterogeneity of negative symptoms by using criteria easily applicable in the context of clinical trials, the concept of persistent negative symptoms (PNS) was developed. Both PNS and DS constructs include enduring negative symptoms (at least 6months for PNS and 12months for DS) that do not respond to available treatments. PNS exclude secondary negative symptoms based on a cross-sectional evaluation of severity thresholds on commonly used rating scales for positive symptoms, depression and extrapyramidal side effects; the DS diagnosis, instead, excludes all potential sources of secondary negative symptoms based on a clinical longitudinal assessment. In this paper we review the evolution of concepts and assessment modalities relevant to PPNS, data on prevalence of DS and PNS, as well as studies on clinical, neuropsychological, brain imaging electrophysiological and psychosocial functioning aspects of DS and PNS.

Aberrant spontaneous neural activity and correlation with evoked-brain potentials in first-episode, treatment-naïve patients with deficit and non-deficit schizophrenia

The goals of the study were to analyze spontaneous neural activity between deficit and non-deficit schizophrenia (DS, NDS) using resting-state fMRI, and to investigate the correlation of fMRI with clinical features and evoked brain potentials. The amplitude of low frequency fluctuation (ALFF) was measured in 41 DS participants, 42 NDS participants, and 42 healthy controls. ALFF in the bilateral cerebellum posterior lobe was significantly decreased in patients, while ALFF in the right fusiform gyrus and the bilateral putamen was significantly increased. In schizophrenia patients, ALFF in the right putamen positively correlated with excited/activation on Positive and Negative Syndrome Scale (PANSS-EXC/ACT). In DS patients, ALFF in the right insula was significantly increased than in controls and positively correlated with S2-P50 amplitude of sensory gating P50. ALFF in the left cerebellum posterior lobe negatively correlated with negative symptoms and withdrawn on PANSS (PANSS-NS, PANSS-WIT), ALFF in the right putamen positively correlated with PANSS-WIT. In NDS patients, ALFF in the middle temporal gyrus decreased than in controls and negatively correlated with P3b subcomponent of P300 latency. ALFF in the left cerebellum posterior lobe negatively correlated with PANSS-EXC/ACT. The middle temporal gyrus in NDS or the right insula in DS may show spatiotemporal defects.

The Course of Neurocognitive Changes in Acute Psychosis: Relation to Symptomatic Improvement

INTRODUCTION

Cognitive impairment is a core aspect of psychosis, but the course of cognitive functioning during acute psychosis remains poorly understood, as does the association between symptom change and neurocognitive change. Some studies have found cognitive improvement to be related to improvement in negative symptoms, but few have examined cognitive changes in the early acute phase, when clinical improvement mainly happens. This study's aim was to investigate the relation between cognitive and symptomatic change in clinically heterogeneous patients during the early acute phase of psychosis.

METHOD

Participants (n = 84), including both first-episode and previously ill patients, were recruited from consecutive admissions to the acute psychiatric emergency ward of Haukeland University Hospital, Bergen, Norway, as part of the Bergen Psychosis Project (BPP). The RBANS neurocognitive test battery was administered on admission and again at discharge from the acute ward (mean time 4.1 weeks, SD 1.86 weeks). Symptomatic change was measured by PANSS.

RESULTS

The proportion of subjects with cognitive impairment (t < 35) was 28.6% in the acute phase and 13.1% at follow-up. A sequential multiple linear regression model with RBANS change as the dependent variable found PANSS negative symptoms change to significantly predict total RBANS performance improvement (beta = -.307, p = .016). There was no significant difference between subjects with schizophrenia and those with other psychotic disorders in terms of cognitive change.

CONCLUSION

The proportion of subjects with mild to moderate impairment in cognitive test performance is reduced across the acute phase of psychosis, with improvement related to amelioration of negative symptoms.

Evidence for Genetic Overlap Between Schizophrenia and Age at First Birth in Women

IMPORTANCE

A recently published study of national data by McGrath et al in 2014 showed increased risk of schizophrenia (SCZ) in offspring associated with both early and delayed parental age, consistent with a U-shaped relationship. However, it remains unclear if the risk to the child is due to psychosocial factors associated with parental age or if those at higher risk for SCZ tend to have children at an earlier or later age.

OBJECTIVE

To determine if there is a genetic association between SCZ and age at first birth (AFB) using genetically informative but independently ascertained data sets.

DESIGN, SETTING, AND PARTICIPANTS

This investigation used multiple independent genome-wide association study data sets. The SCZ sample comprised 18 957 SCZ cases and 22 673 controls in a genome-wide association study from the second phase of the Psychiatric Genomics Consortium, and the AFB sample comprised 12 247 genotyped women measured for AFB from the following 4 community cohorts: Estonia (Estonian Genome Center Biobank, University of Tartu), the Netherlands (LifeLines Cohort Study), Sweden (Swedish Twin Registry), and the United Kingdom (TwinsUK). Schizophrenia genetic risk for each woman in the AFB community sample was estimated using genetic effects inferred from the SCZ genome-wide association study.

MAIN OUTCOMES AND MEASURES

We tested if SCZ genetic risk was a significant predictor of response variables based on published polynomial functions that described the relationship between maternal age and SCZ risk in offspring in Denmark. We substituted AFB for maternal age in these functions, one of which was corrected for the age of the father, and found that the fit was superior for the model without adjustment for the father's age.

RESULTS

We observed a U-shaped relationship between SCZ risk and AFB in the community cohorts, consistent with the previously reported relationship between SCZ risk in offspring and maternal age when not adjusted for the age of the father. We confirmed that SCZ risk profile scores significantly predicted the response variables (coefficient of determination R2 = 1.1E-03, P = 4.1E-04), reflecting the published relationship between maternal age and SCZ risk in offspring by McGrath et al in 2014.

CONCLUSIONS AND RELEVANCE

This study provides evidence for a significant overlap between genetic factors associated with risk of SCZ and genetic factors associated with AFB. It has been reported that SCZ risk associated with increased maternal age is explained by the age of the father and that de novo mutations that occur more frequently in the germline of older men are the underlying causal mechanism. This explanation may need to be revised if, as suggested herein and if replicated in future studies, there is also increased genetic risk of SCZ in older mothers.

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

Low IQ has recently been shown to predict neuropsychological effort test failure in healthy and neurological populations. Although low IQ is common in schizophrenia (SZ), its effect on effort test performance remains unclear in this population. The current study examined the role of IQ in effort test performance in a sample of 60 outpatients with SZ and 30 demographically matched healthy controls (CN). Participants were administered a battery of neuropsychological tests, and insufficient effort was calculated using two embedded effort indices: the Reliable Digit Span Effort Index and the Finger Tapping Effort Index. Results indicated that 16.1% of SZ patients and 0% CN failed both effort measures and that 32.1% of SZ and 3.3% of CN failed one measure. In SZ, IQ in the <70 or 70-79 range was associated with the highest rates of falling below the effort cut-off scores; however, patients with IQs in the low-average or higher range (>80) did not fall below effort cut-offs. Findings suggest that low IQ is a significant predictor of insufficient effort during neuropsychological test performance in schizophrenia, calling into question the validity of neuropsychological effort testing in SZ patients with low IQ.