Advanced Clinical Interpretation of the WAIS-IV and WMS-IV: Prevalence of Low Scores Varies by Level of Intelligence and Years of Education
Alberta Children's Hospital and University of Calgary, Canada.Assessment (Impact Factor: 3.29). 06/2011; 18(2):156-67. DOI: 10.1177/1073191110385316
Clinicians can use the base rates of low scores in healthy people to reduce the likelihood of misdiagnosing cognitive impairment. In the present study, base rates were developed for the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) and Wechsler Memory Scale-Fourth Edition (WMS-IV) using 900 healthy adults and validated on 28 patients with moderate or severe traumatic brain injuries (TBIs). Results indicated that healthy people obtain some low scores on the WAIS-IV/WMS-IV, with prevalence rates increasing with fewer years of education and lower predicted intelligence. When applying the base rates information to the clinical sample, the TBI patients were 13 times more likely to be identified as having a low cognitive profile compared with the controls. Using the base rates information is a psychometrically advanced method for establishing criteria to determine low cognitive abilities on the WAIS-IV/WMS-IV.
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- "A review of the literature resulted in only a handful of studies addressing the psychometric properties of the Designs subtest. Previous studies involving the Designs subtests have examined the factor structure of subtests of the WMS-IV and WAIS-IV combined (Holdnack, Zhou, Larrabee, Millis, & Salthouse, 2011), relationships between WMS-IV subtests and a measure of activities of daily living (Drozdick & Cullum, 2011), and prevalence of low scores on WMS-IV subtests in the normative sample (Brooks, Holdnack, & Iverson, 2011). In a principal component analysis of the WMS-IV normative sample by age group, the Designs subtests loaded onto the same dimension as the Visual Reproduction subtests for all age groups except for the 65– 69 group (Hoelzle, Nelson, & Smith, 2011). "
ABSTRACT: The Designs subtest allows for accumulation of raw score points by chance alone, creating the potential for artificially inflated performances, especially in older patients. A random number generator was used to simulate the random selection and placement of cards by 100 test naive participants, resulting in a mean raw score of 36.26 (SD = 3.86). This resulted in relatively high-scaled scores in the 45-54, 55-64, and 65-69 age groups on Designs II. In the latter age group, in particular, the mean simulated performance resulted in a scaled score of 7, with scores 1 SD below and above the performance mean translating to scaled scores of 5 and 8, respectively. The findings indicate that clinicians should use caution when interpreting Designs II performance in these age groups, as our simulations demonstrated that low average to average range scores occur frequently when patients are relying solely on chance performance.
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- "ith and without cognitive impairment ( Brooks et al . , 2011 ) . Convergent validity was supported by our data . Furthermore , this study is one of the first to highlight group differences between com - plicated mild / moderate and severe TBI using the WMS ; most previous WMS – II / WMS – IV work in TBI has focused on only moderate or severe TBI ( Brooks et al . , 2011 ; Langeluddecke & Lucas , 2005 ; Skandsen et al . , 2010 ; Walker , Batchelor , Shores , & Jones , 2009 ) , has not distinguished between mild and complicated mild TBI ( Fisher et al . , 2000 ; West et al . , 2011 ) , or has not distinguished complicated mild TBI from other TBI groups ( i . e . , only exam - ined TBI relative to control"
ABSTRACT: This study was designed to examine the construct validity of the Wechsler Memory Scale-Fourth Edition (WMS-IV) in individuals with traumatic brain injury (TBI). One hundred individuals with TBI (n = 35 complicated mild/moderate TBI; n = 65 severe TBI) and 100 matched controls from the WMS-IV normative dataset completed the WMS-IV. Multivariate analyses indicated that severe TBI participants had poorer performance than matched controls on all index scores and subtests. Individuals with complicated mild/moderate TBI performed more poorly than controls on all index scores, as well as on tests of visual memory (Designs I and II; Visual Reproduction I and II) and visual working memory (Spatial Addition; Symbol Span), but not on auditory verbal memory tests (Logical Memory I and II; Verbal Paired Associates I and II). After controlling for time since injury, severe TBI participants had significantly lower scores than the complicated mild/moderate TBI on 4 of the 5 WMS-IV index scores (Auditory Memory, Visual Memory, Immediate Memory, Delayed Memory) and 4 of the 10 WMS-IV subtests (Designs I and II, Verbal Pairs II, Logical Memory II). Effect sizes for index and subtest scores were generally moderate for the complicated mild/moderate group and moderate-to-large for the severe TBI group. Findings provide support for the construct validity of the WMS-IV in individuals with TBI.
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ABSTRACT: The frequencies of differences between highest and lowest subtest scores as a function of highest subtest score (relative scatter), are reported for the standardization sample of the Wechsler Adult Intelligence Scale-IV (WAIS-IV). Large differences between highest and lowest subtest scores were common. The degree of relative scatter was related to the height of the highest subtest score. For the 10 core WAIS-IV subtests, the correlation between the level of the highest subtest score and the amount of scatter was r = .62; for all 15 subtests the correlation was. 63. The level of the highest subtest score was more strongly related to scatter than was Full Scale IQ. Clinical implications for inferring cognitive impairment and estimating premorbid abilities are discussed. When considering the possibility of acquired cognitive impairment, we recommend caution in the interpretation of subtest score differences.
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