More recently, Bortnik and colleagues (2013) examined performance on four PVTs in 128 veterans with dementia diagnoses who were separated into “good-effort” and “suspect-effort” groups. Additionally, it was found that those with lower scores (i.e., greater impairment) on the Mini Mental Status Examination (MMSE Folstein, Folstein, & McHugh, 1975), failed a greater number of PVTs ( Dean et al., 2009). Using established cutoffs, inadequate specificity rates were found for 16 of these PVTs. In one of the most comprehensive reviews of PVTs in older adults, Dean and colleagues (2009) examined the clinical utility of 18 PVTs in a sample of 214 non-litigating individuals diagnosed with various types of dementia. A small number of recent studies have examined the use of various free-standing and embedded PVTs in individuals with dementia, generally finding that using previously established cutoffs resulted in poor specificity rates ( Bortnik, Horner, & Bachman, 2013 Dean, Victor, Boone, Philpott, & Hess, 2009 Merten et al., 2007). As such, the level of cognitive impairment typically seen in dementia may interfere with the ability to “pass” PVTs using established cutoffs, despite adequate effort ( Teichner & Wagner, 2004). However, significant cognitive impairment can lead to difficulty completing PVTs ( Howe, Anderson, Kaufman, Sachs, & Loring, 2007 Merten, Bossink, & Schmand, 2007), especially embedded measures such as the RDS, which are more sensitive to actual cognitive functioning, as opposed to stand-alone PVTs that are theoretically so simple as to be robust to cognitive impairment. In most instances, PVT failure is thought to reflect suboptimal effort rather than cognitive impairment. The primary aim of the current study was to explore the prevalence of above and below criterion performance for several published RDS cut scores in a large outpatient dementia sample. Substantially less attention has been paid to how validity measures operate in populations of older adults, particularly those suspected for dementia, as these individuals are often excluded from validation studies of performance validity tests (PVTs). Much of the research to date regarding performance validity, including use of RDS, has been done with adults with an overrepresentation of traumatic brain injury. Reliable Digit Span (RDS Greiffenstein, Baker, & Gola, 1994) is a well-established embedded measure of performance validity ( Boone, 2007 Schroeder, Twumasi-Ankrah, Baade, & Marshall, 2012) that can be derived from standard DS administration. The digit span (DS) subtest from the Wechsler Adult Intelligence Scale-IV (WAIS-IV Wechsler, 2008) is one of the most frequently used measures of attention and working memory ( Hales, Yudofsky, & Roberts, 2014 Rabin, Barr, & Burton, 2005). These tests are designed to ensure that the results obtained from a neuropsychological evaluation are in fact a valid representation of an individual's cognitive abilities ( Boone, 2007 Larrabee, 2012). Given findings indicating effort accounts for a large percentage of variance in neuropsychological test performance ( Fox, 2011 Green, Rohling, Lees-Haley, & Allen, 2001 Meyers, Volbrecht, Axelrod, & Reinsch-Boothby, 2011), objective measures of effort have been developed to try to identify inconsistent performance. Dementia, Malingering/symptom validity testing, Assessment, Reliable Digit SpanĮvaluating the validity of neuropsychological profiles is an essential part of clinical care in both litigating and non-litigating contexts ( Bush et al., 2005 Heilbronner, Sweet, Morgan, Larrabee, & Millis, 2009 McCrea et al., 2008), and recent research has highlighted the importance of assessing performance validity in research settings as well ( An, Zakzanis, & Joordens, 2012 DeRight & Jorgensen, 2015 Silk-Eglit et al., 2014).
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