The evaluation of insufficient cognitive effort in schizophrenia in light of low IQ scores Kayla M. Whearty a , Daniel N. Allen b , Bern G. Lee b , Gregory P. Strauss a, * a State University of New York at Binghamton, Department of Psychology, USA b University of Nevada Las Vegas, Department of Psychology, USA article info Article history: Received 28 January 2015 Received in revised form 13 April 2015 Accepted 23 April 2015 Keywords: Effort Cognition Neuropsychology Psychosis Negative symptoms abstract 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 70e79 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. © 2015 Elsevier Ltd. All rights reserved. 1. Introduction Early clinical conceptualizations of schizophrenia (SZ) consid- ered cognitive impairment to be a core feature of the disease (Kraepelin, 1919). Modern empirical studies have confirmed these observations, with meta-analyses of neuropsychological test per- formance indicating that SZ patients perform on the order of 1.0 standard deviation below that of healthy controls on standardized tests (Dickinson et al., 2007; Fioravanti et al., 2005). However, studies have yet to uncover a neurocognitive profile or pattern of differential deficits that characterizes the majority of people with SZ (Reichenberg and Harvey, 2007). Rather, individuals with SZ have been found to display deficits of similar magnitude across a range of cognitive domains (e.g., attention, working memory, ex- ecutive functioning), with moderate interrelationships among tests (Dickinson, 2008; Dickinson et al., 2004, 2008). These findings have lead some to suggest that SZ is characterized by a “generalized neurocognitive deficit” (Dickinson and Harvey, 2009; Dickinson et al., 2008). Several biological accounts have been proposed to explain the generalized neurocognitive deficit in SZ, including central nervous system (CNS) (e.g., impaired signal integration across neural net- works, gray and white matter abnormalities, NMDA and GABA interneuron receptor dysfunction) (Dickinson and Harvey, 2009) and “general systems” abnormalities (e.g., inflammation, oxidative stress, metabolic dysfunction) (Asevedo et al., 2013; Friedman et al., 2010; Lindenmayer et al., 2012; Ribeiro-Santos et al., 2014). How- ever, psychological explanations of the generalized neurocognitive deficit have received relatively little attention despite the fact that clinicians have long suspected that symptoms of avolition and apathy lead some patients to put forth insufficient effort during neuropsychological testing. The field of clinical neuropsychology has developed and validated several measures designed to detect insufficient effort during neuropsychological testing (Sollman and Berry, 2011; Vickery et al., 2001). When these measures have been applied to study insufficient effort in SZ, inconsistent rates of effort test failure have been observed. 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 * Corresponding author. State University of New York at Binghamton, Depart- ment of Psychology, PO Box 6000, Binghamton, New York, 13902-6000, USA. Tel.: þ1 607 777 5408; fax: þ1 607 777 4890. E-mail address: gstrauss@binghamton.edu (G.P. Strauss). Contents lists available at ScienceDirect Journal of Psychiatric Research journal homepage: www.elsevier.com/locate/psychires http://dx.doi.org/10.1016/j.jpsychires.2015.04.018 0022-3956/© 2015 Elsevier Ltd. All rights reserved. Journal of Psychiatric Research xxx (2015) 1e8 Please cite this article in press as: Whearty KM, et al., The evaluation of insufficient cognitive effort in schizophrenia in light of low IQ scores, Journal of Psychiatric Research (2015), http://dx.doi.org/10.1016/j.jpsychires.2015.04.018