Differential WAIS/WAIS-R IQ discrepancies among institutionalized mentally retarded persons

Compared to the Wechsler Adult Intelligence Scale, the Wechsler Adult Intelligence Scale-Revised (WAIS-R) is generally reported to result in IQs that are somewhat lower for nonretarded subjects and unchanged for retarded subjects. In the present study these findings were replicated with subjects in a residential treatment center, except that the moderately retarded subgroup demonstrated significantly higher WAIS-R IQs (mean increase of 6 points in Full Scale IQ), with reclassification as mildly mentally retarded possible for 64% of these persons. Such differential, level-specific effects require careful interpretation of WAIS-R IQs of retarded persons in the context of actual adaptive skills.     

Fine tuning of the digit symbol paired associate recall test for practitioner purposes in clinical and research settings

Guidelines are presented to facilitate the use of the WAIS Digit Symbol measure of paired associate recall as a neuropsychological instrument. Currently three formal variants of the test exist with accompanying normative data (the original WAIS-R-NI form; a WAIS-R Short Form; a longer WAIS-III form), providing a potential source of confusion which may limit its application. To circumvent this, the present article critically evaluates: (i) variations in test forms and their advantages; (ii) available norms in terms of age and education, with pointers for more differentiated guidelines in this regard; and (iii) the desirability of incorporating a delayed recall variant of the test. Finally, a synopsis of data is presented that supports the screening potential of Digit Symbol paired associate recall in cases of mild neurocognitive dysfunction. For the purposes of this paper, the term WAIS is used with broad reference to all variations of the original Wechsler Adult Intelligence Scale (1955) upon which they were based, including the WAIS-R (1981) and WAIS-III (1997) updated editions, and the South African WAIS (1969). The terms South African WAIS (South African Wechsler Adult Intelligence Scale), WAIS-R (Wechsler Adult Intelligence Scale - Revised), and WAIS-III (Wechsler Adult Intelligence Scale-III), refer to these specific versions of the test.     

A comparison of the WAIS and WAIS-R using T-score conversions that correct for age, education, and sex

A newly developed T score conversion system that corrects Wechsler Adult Intelligence Scale (WAIS) and Wechsler Adult Intelligence Scale-Revised (WAIS-R) subtest and IQ scores for appropriate demographic variables was used to compare subjects' performance on the two versions of the instrument. Using 428 pairs of subjects matched on age, education, and sex, with one person in each pair having taken the WAIS and the other the WAIS-R, we found no significant differences in level or pattern of performance when analyses were performed on the T scores. This was in contrast to highly significant differences when uncorrected scaled scores and IQ values were compared. Therefore, the T score system appears to provide a tool which may help clinicians make more direct comparisons between the results obtained on the WAIS and WAIS-R.     

Inadequacy of brief IQ measures in the classification of mentally retarded prisoners.

This study was designed to evaluate the use of the Slosson Intelligence Test (SIT) and a Wechsler Adult Intelligence Scale (WAIS) short form in determining the intellectual capacity and educational/treatment needs of mentally retarded offenders. The subjects were 52 male prisoners with borderline or retarded intellectual functioning. Their WAIS full-scale IQs were found to be significantly different from their WAIS short-form and SIT IQs. These results suggest that we must continue to use the full WAIS in evaluating mentally retarded offenders.     

A comparison of the wais and wais-r using t-score conversions that correct for age,education, and sex

Abstract

A newly developed T score conversion system that corrects Wechsler Adult Intelligence Scale (WAIS) and Wechsler Adult Intelligence Scale-Revised (WAIS-R) subtest and IQ scores for appropriate demographic variables was used to compare subjects' performance on the two versions of the instrument. Using 428 pairs of subjects matched on age, education, and sex, with one person in each pair having taken the WAIS and the other the WAIS-R, we found no significant differences in level or pattern of performance when analyses were performed on the T scores. This was in contrast to highly significant differences when uncorrected scaled scores and IQ values were compared. Therefore, the T score system appears to provide a tool which may help clinicians make more direct comparisons between the results obtained on the WAIS and WAIS-R.     

Wechsler Intelligence Scale profiles, the cholinergic system, and Alzheimer's disease

Forty-one patients with putative Alzheimer's Disease (AD) were evaluated to determine the diagnostic utility of a profile of Wechsler Adult Intelligence Scale (WAIS) subtests which has been proposed by Fuld (1984) to identify cholinergic dysfunction. Only nine (21.9%) of these patients had positive Wechsler profiles. Half (n = 21) of the AD patients had been given the WAIS, and the other half (n = 20) the Wechsler Adult Intelligence Scale-Revised (WAIS-R). Positive profiles occurred more often in the AD subgroup given the WAIS-R, but this difference was not statistically significant. Specificity of the formula was evaluated using Wechsler results of 42 older normals and 30 patients who were being evaluated for dementia but who did not have AD. One of the 42 normals (2.4%) and five of the patient controls (16.7%) showed a positive Wechsler profile. Because of the Fuld formula's low sensitivity, a negative Wechsler profile cannot be used to help rule out AD. Although specificity of the formula is high, the diagnostic value of a positive Wechsler profile is modest even under the most favorable AD baserate conditions.     

Assessment of the accuracy of regression equations proposed for estimating premorbid intellectual functioning on the Wechsler Adult Intelligence Scale

This investigation examined the accuracy of regression equations proposed by Wilson et al. (1978) for estimating premorbid intellectual quotients (IQs) on the Wechsler Adult Intelligence Scale (WAIS). Actual Verbal, Performance, and Full Scale IQs in a sample of 69 neurologically normal adults were compared against their estimated premorbid levels. While the equations provided an adequate overall fit to the data, actual IQ values at the extremes of the WAIS Scales were found to be most susceptible to underestimation (high actual IQ values) or overestimation (low actual IQ values). The clinical importance of this finding and possible applications of the equations are discussed.     

Disparities in mentally retarded persons' IQs derived from different intelligence tests

For mildly and moderately mentally retarded individuals, the Wechsler Adult Intelligence Scale--Revised measures at about the same level as the Wechsler Adult Intelligence Scale, and, consequently, it also produces much higher IQs than do the Wechsler children's scales or the Stanford-Binet Intelligence Scale, Form L-M, despite high intertest correlations. This unsatisfactory state of affairs is due primarily to inadequate standardization sampling, particularly in the lower range of intelligence. Rather than abandon the IQ, corrective action should be taken.     

The National Adult Reading Test: restandardisation against the Wechsler Adult Intelligence Scale—Fourth edition

Since publication in 1982, the 50-item National Adult Reading Test (NART; Nelson, 1982; NART–R; Nelson & Willison, 1991) has remained a widely adopted method for estimating premorbid intelligence both for clinical and research purposes. However, the NART has not been standardised against the most recent revisions of the Wechsler Adult Intelligence Scale (WAIS-III; Wechsler, 1997, and WAIS-IV; Wechsler, 2008). Our objective, therefore, was to produce reliable standardised estimates of WAIS-IV IQ from the NART. Ninety-two neurologically healthy British adults were assessed and regression equations calculated to produce population estimates of WAIS-IV full-scale IQ (FSIQ) and constituent index scores. Results showed strong NART/WAIS-IV FSIQ correlations with more moderate correlations observed between NART error and constituent index scores. FSIQ estimates were closely similar to the published WAIS and WAIS-R estimates at the high end of the distribution, but at the lower end were approximately equidistant from the highly discrepant WAIS (low) and WAIS-R (high) values. We conclude that the NART is likely to remain an important tool for estimating the impact of neurological damage on general cognitive ability. We advise caution in the use of older published WAIS and/or WAIS-R estimates for estimating premorbid WAIS-IV FSIQ, particularly for those with low NART scores.     

Discrepancies between IQ and memory scores in alcoholism and aging

Standardized IQ and memory tests were administered to 30 alcoholic men (7 with Korsakoff's syndrome) and 29 nonalcoholic controls between 24 and 74 years of age, in order to evaluate alcohol-related discrepancies between IQ and memory scores (including those attributable to possible premature aging). Severity of amnesia often has been defined operationally as a large discrepancy between IQ scores on the Wechsler Adult Intelligence Scale (WAIS), and scores on memory tests such as the Wechsler Memory Scale (WMS). In the context of a normal WAIS Full Scale IQ or Verbal IQ, a low WMS memory quotient (MQ) signals the possibility of anterograde memory disorder. Revised and nonrevised versions of the WAIS and WMS were given to all of the subjects. As expected, the revised versions yielded lower scores than the non-revised versions; these differences were especially prominent in the older subjects (whether or not they had a history of alcoholism) and the Korsakoff patients. Korsakoff patients demonstrated the largest discrepancies between IQ and memory scores, regardless of the tests being used. Results indicated that measures used clinically to reveal amnesia, that is, large differences between IQ scores and memory scores, were effective in any combination (the WAIS or the WAIS-R with the WMS or the WMS-R).     

The test-retest reliability and stability of the WAIS-R in a sample of mentally retarded adults

ABSTRACT. Fifty mentally retarded adults were administered the Wechsler Adult Intelligence Scale-Revised (WAIS-R) on two separate occasions, with the mean amount of time between testings being 2 years, 8 months. The data were examined in an effort to study the test-retest reliability and stability of the WAIS-R with the mentally retarded. Based on correlational, t -value and percentage of scale score change information, the authors concluded that the WAIS-R IQs appeared to possess good test-retest reliability and stability over an approximate 2–5 year period for the present sample of mentally retarded adults.     

Comparison of linear equating and prorated short forms for estimating WAIS-R FSIQ in a neuropsychological population

Comparisons were made of estimates of the Wechsler Adult Intelligence Scale - Revised Full Scale IQ using the two-,three- and four-subtest linear equating procedures of Kaufman (1990) and Booker and Cyr (1986) with FSIQ estimates using prorating to obtain FSIQ scores. The advantage of prorating is that it affords greater clinical flexibility in selection of subtests. The participants were 64 neuropsychiatric patients who completed the full WAIS-R from which short form and FSIQ were calculated. Prorating yielded estimates of mean IQ and categorization of IQ comparable to IQs obtained by linear equating, though there was an increased likelihood of disparate results with extreme IQ scores. Prudent clinical judgment is recommended for situations involving unusual or extreme scaled score patterns, particularly when the number of subtests is small.     

Wais versus wais-r subtest patterns: A problem of generalization

Abstract

While the Wechsler Adult Intelligence Scale-Revised (WAIS-R) has gained considerable acceptance as a satisfactory successor to the WAIS as a measure of general intelligence, few studies have examined whether the two tests are comparable in terms of brain-behavior relationships. To evaluate the equivalence of profile interpretations of the WAIS and WAIS-R, the tests were given in a concurrent manner to 43 patients referred for neuropsychological evaluation. While subtest and summary IQ scores were highly correlated, the WAIS-R yielded significantly lower scores than did the WAIS, but not in a uniform manner. Subtest differences ranged from .56 to 2.42, indicating that the WAIS-R introduces a systematic profile bias. Ipsative correlations between profile patterns for each patient ranged from .233 to .986, with a mean correlation of .860. Finally, concordance rates for decisions based on three objective profile rules were examined for the WAIS and WAIS-R data. Concordance rates between tests for “positive” cases ranged from 41.7% to 65.5%. These results suggest that neuropsychological inferences derived from the patterning of WAIS-R subtest scores should be validated empirically and should not be assumed to be comparable with those previously established with the WAIS.     

Comparison of Linear Equating and Prorated Short Forms for Estimating WAIS-R FSIQ in a Neuropsychological Population

Comparisons were made of estimates of the Wechsler Adult Intelligence Scale – Revised Full Scale IQ using the two-,three- and four-subtest linear equating procedures of Kaufman (1990) and Booker and Cyr (1986) with FSIQ estimates using prorating to obtain FSIQ scores. The advantage of prorating is that it affords greater clinical flexibility in selection of subtests. The participants were 64 neuropsychiatric patients who completed the full WAIS-R from which short form and FSIQ were calculated. Prorating yielded estimates of mean IQ and categorization of IQ comparable to IQs obtained by linear equating, though there was an increased likelihood of disparate results with extreme IQ scores. Prudent clinical judgment is recommended for situations involving unusual or extreme scaled score patterns, particularly when the number of subtests is small.     

Value of ancillary testing in the diagnosis of pervasive developmental disorder in adults

Recently, there has been increasing interest in adults with pervasive developmental disorder (PDD) who seek general psychiatric services for various psychiatric problems. The diagnosis of PDD requires the careful collection of information about the patient's developmental history. A structured diagnostic interview is useful and should be performed, but has limitations now. The clinical value of the measurement of the Wechsler Adult Intelligence Scale, the Autism-Spectrum Quotient Japanese Version, and the Pervasive Developmental Disorders Autism Society Japan Rating Scale was demonstrated by a questionnaire survey that the authors conducted in 2010. These additional tests are useful if interpreted with caution. For example, a discrepancy between the performance intelligence quotient (IQ) and the verbal IQ in the Wechsler Adult Intelligence Scale does not by itself diagnose PDD. We examined whether the Japanese version of the National Adult Reading Test (Japanese Adult Reading Test; JART), a valid scale for evaluating pre-morbid IQ in patients with schizophrenia, and the Wechsler Adult Intelligence Scale-Revised (WAIS-R) are useful for discriminating between PDD and schizophrenia. Sixteen patients with adult PDD and 16 patients with schizophrenia matched for age, education and sex participated in this study. In addition, the two groups were matched for JART and the Global Assessment of Functioning scores. All subjects were scored on the JART and WAIS-R after giving informed consent for the study. The result was that significant diagnosis-by-IQ examination interactions were found (F [1, 30]=10.049, P=0.003). Also, the WAIS-R scores of the PDD group were higher than those of the schizophrenia group (P=0.002) when the two groups were matched for JART. In conclusion, the comparison of IQ in the PDD group and in the schizophrenia group by JART and WAIS-R might be an easy and useful method for helping to discriminate between PDD and schizophrenia. In addition, the difference in IQ scores measured by JART and by WAIS-R may be helpful in diagnosing PDD. The diagnosis of PDD in adults may be assisted by the use of these additional tests.     

Intellectual and memory impairment in dementia. Computerized axial tomography volume correlations

Ventricular volume estimates and an index of cerebral atrophy were obtained from computerized axial tomography scans of patients with presenile or senile dementia of probable Alzheimer's type. These measures were used to examine the correlation between morphological brain change and performance on the Wechsler Adult Intelligence Scale (WAIS) and the Wechsler Memory Scale (WMS). Despite ventricular volumes in excess of 60% larger than normal, no significant correlations were found between ventricular size and WAIS or WMS performance. The index of pericerebral atrophy did correlate negatively with various WAIS measures, particularly Performance IQ, and some aspects of WMS performance. Results suggest that in Alzheimer's disease, pericerebral atrophy measures, but not ventricular dilation, correlate with intellectual decline and certain aspects of memory impairment.     

Use of the Wechsler Adult Intelligence Scale Digit Span subtest for malingering detection: a meta-analytic review

Twenty-four studies utilizing the Wechsler Adult Intelligence Scale (WAIS) Digit Span subtest--either the Reliable Digit Span (RDS) or Age-Corrected Scaled Score (DS-ACSS) variant--for malingering detection were meta-analytically reviewed to evaluate their effectiveness in detecting malingered neurocognitive dysfunction. RDS and DS-ACSS effectively discriminated between honest responders and dissimulators, with average weighted effect sizes of 1.34 and 1.08, respectively. No significant differences were found between RDS and DS-ACSS. Similarly, no differences were found between the Digit Span subtest from the WAIS or Wechsler Memory Scale (WMS). Strong specificity and moderate sensitivity were observed, and optimal cutting scores are recommended.     

Accuracy of the seven subtest WAIS-R short form in chronic schizophrenia.

The accuracy of the WAIS-R seven subtest short form (Ward, L.C., 1990. Prediction of Verbal, Performance and Full Scale IQs from seven subtests of the WAIS-R. J. Clin. Psychol. 46, 436-440) was examined for predicting IQs of 73 inpatients diagnosed with schizophrenia. Results indicated that 93% of the estimated Full Scale IQs were within +/-5 points of their actual scores. Using Wechsler's (1981) seven category intelligence classification, the level of agreement on the Full Scale IQ was 84% for the standard WAIS-R and the seven subtest short form. This abbreviated Wechsler Scale may be used with schizophrenic patients when only general estimates of intellectual functioning are required.     

Sex differences among non-brain-damaged adults on the Wechsler Adult Intelligence Scales: a review of the literature

We reviewed studies of the performance of non-brain-damaged men and women on the Wechsler Adult Intelligence Scales (i.e., the Wechsler-Bellevue, Wechsler Adult Intelligence Scale, and Wechsler Adult Intelligence Scale-Revised) to determine if there were sex differences on specific test items, on specific subtests, or on Verbal IQ, Performance IQ, or the Verbal-Performance Discrepancy score. There were sex differences on some items of each of the three measures, but the number of such differences was small. A number of studies suggested differences on subtests of these scales. A meta-analysis indicated that females tended to outperform males by about a third of a standard deviation on the Digit Symbol subtest, while males tended to outperform females to the same extent or greater on the Arithmetic and Information subtests. Finally, in the few studies on IQ or discrepancy-score differences, there was no evidence of any consistent differences between the sexes in the Verbal-Performance Discrepancy, although there was some tendency for males to obtain higher Verbal IQs. This review, therefore, does not suggest that there are any major differences between non-brain-damaged males and females on the Wechsler adult intelligence scales.     

Detection of mild cognitive deficits in Parkinson's disease patients with the WAIS-R NI.

The relative insensitivity of traditional IQ tests to mild cognitive deficits has led investigators to develop a version of the widely used Wechsler intelligence scales that allows quantitative analysis of underlying qualitative responses. This instrument, the Wechsler Adult Intelligence Scale-Revised as a Neuropsychological Instrument (WAIS-R NI) was administered to 16 Parkinson's disease (PD) patients and 30 normal controls (NC). The 2 groups did not differ significantly in mean age or education, or on their mean Mattis Dementia Rating Scale score. Relative to NC participants, PD patients showed decreased visual attention span, longer response latencies, slower visuomotor processing, and more stimulus-bound errors. Many of the WAIS-R NI measures were able to detect cognitive impairment in a greater percentage of patients than the traditional WAIS-R measures, making it easier to identify deficits that could affect quality of life early in the course of the disease.