Demographic Corrections Research Articles

Demographically corrected norms for African Americans and Caucasians on the Hopkins Verbal Learning Test–Revised, Brief Visuospatial Memory Test–Revised, Stroop Color and Word Test, and Wisconsin Card Sorting Test 64-Card Version

Memory and executive functioning are two important components of clinical neuropsychological (NP) practice and research. Multiple demographic factors are known to affect performance differentially on most NP tests, but adequate normative corrections, inclusive of race/ethnicity, are not available for many widely used instruments. This study compared demographic contributions for widely used tests of verbal and visual learning and memory (Brief Visual Memory Test–Revised, Hopkins Verbal Memory Test–Revised) and executive functioning (Stroop Color and Word Test, Wisconsin Card Sorting Test–64) in groups of healthy Caucasians (n = 143) and African Americans (n = 103). Demographic factors of age, education, gender, and race/ethnicity were found to be significant factors on some indices of all four tests. The magnitude of demographic contributions (especially age) was greater for African Americans than for Caucasians on most measures. New, demographically corrected T-score formulas were calculated for each race/ethnicity. The rates of NP impairment using previously published normative standards significantly overestimated NP impairment in African Americans. Utilizing the new demographic corrections developed and presented herein, NP impairment rates were comparable between the two race/ethnicities and were unrelated to the other demographic characteristics (age, education, gender) in either race/ethnicity group. Findings support the need to consider extended demographic contributions to neuropsychological test performance in clinical and research settings.

Demographic corrections appear to compromise classification accuracy for severely skewed cognitive tests

Demographic corrections for cognitive tests should improve classification accuracy by reducing age or education biases, but empirical support has been equivocal. Using a simulation procedure, we show that creating moderate or extreme skewness in cognitive tests compromises the classification accuracy of demographic corrections, findings that appear replicated within clinical data for the few neuropsychological test scores with an extreme degree of skew. For most neuropsychological tests, the dementia classification accuracy of raw and demographically corrected scores was equivalent. These findings suggest that the dementia classification accuracy of demographic corrections is robust to slight degrees of skew (i.e., skewness <1.5).

Prediction of driving ability with neuropsychological tests: Demographic adjustments diminish accuracy

Demographically adjusted norms generally enhance accuracy of inferences based on neuropsychological assessment. However, we hypothesized that demographic corrections diminish predictive accuracy for real-world activities with absolute cognitive demands. Driving ability was assessed with a 45-minute drive along a standardized on-road route in participants aged 65+ (24 healthy elderly, 26 probable Alzheimer's disease, 33 Parkinson's disease). Neuropsychological measures included: Trail-Making A and B, Complex Figure, Benton Visual Retention, and Block Design tests. A multiple regression model with raw neuropsychological scores was significantly predictive of driving errors (R2 = .199, p = .005); a model with demographically adjusted scores was not (R2 = .113, p = .107). Raw scores were more highly correlated with driving errors than were adjusted scores for each neuropsychological measure, and among healthy elderly and Parkinson's patients. When predicting real-world activities that depend on absolute levels of cognitive abilities regardless of demographic considerations, predictive accuracy is diminished by demographic corrections.

Age Corrections and Dementia Classification Accuracy

In contrast to expectations, demographic corrections to reduce biases against those of advanced age or few years of education does not universally improve diagnostic classification accuracy. Age corrections may be particularly problematic because age is also a risk factor for a dementia diagnosis. We found that simulating increased risk for dementia based on demographic variables, such as age, reduced the overall classification accuracy for demographically corrected simulated scores relative to the raw, uncorrected test scores. In clinical data with a small magnitude of association between age and dementia diagnosis, we found equivalent overall classification accuracy for demographically corrected and raw test scores. Regardless of the overall classification accuracy results, cutoff comparisons (16th and 9th percentiles) in clinical and simulated data demonstrated that for the most part, the sensitivity of raw scores was higher than the sensitivity of demographically corrected scores, but the specificity of scores corrected with normative data was superior.

Effects of education and cultural background on performance on WAIS-III, WMS-III, WAIS-R and WMS-R measures: Systematic review

The literature on the effects of education and cultural background on Wechsler Adult Intelligence Scale-III (WAIS-III), Wechsler Memory Scale-III (WMS-III), WAIS-R and WMS-R performances was reviewed. The electronic databases PsycINFO, MEDLINE and PubMed were searched over the period 1980–2008 and reference lists from papers identified were examined for relevant articles. Of 3,081 papers identified, 19 met criteria including English language, group research, adult sample, quantitative data published and focus on relationship between culture and/or education and performances on WAIS-III, WMS-III, WAIS-R or WMS-R measures. There was converging evidence that both education and culture showed significant relationships with test performances, particularly on the WAIS-III and WAIS-R in control and clinical groups. The limited research available did not demonstrate improved diagnostic efficiency with the application of demographic corrections for the WAIS-III. Clinical implications were discussed, including the issue of compromised validity when assessing people from diverse cultural backgrounds for whom relevant normative data are not available. Suggested research directions included the development of culturally and linguistically specific normative data, the modification and validation of “culture-free” tests and the examination of cultural effects in clinical groups in the Australian context.

Diagnostic efficiency of demographically corrected Wechsler Adult Intelligence Scale-III and Wechsler Memory Scale-III indices in moderate to severe traumatic brain injury and lower education levels

Despite the sensitivity of neuropsychological tests to educational level, improved diagnostic accuracy for demographically corrected scores has yet to be established. Diagnostic efficiency statistics of Wechsler Adult Intelligence Scale-III (WAIS-III) and Wechsler Memory Scale-III (WMS-III) indices that were corrected for education, sex, and age (demographically corrected) were compared with age corrected indices in individuals aged 16 to 75 years with moderate to severe traumatic brain injury (TBI) and 12 years or less education. TBI participants (n = 100) were consecutive referrals to an outpatient rehabilitation service and met careful selection criteria. Controls (n = 100) were obtained from the WAIS-III/WMS-III standardization sample. Demographically corrected indices did not provide higher diagnostic efficiency than age corrected indices and this result was supported by reanalysis of the TBI group against a larger and unmatched control group. Processing Speed Index provided comparable diagnostic accuracy to that of combined indices. Demographically corrected indices were associated with higher cut-scores to maximize overall classification, reflecting the upward adjustment of those scores in a lower education sample. This suggests that, in clinical practice, the test results of individuals with limited education may be more accurately interpreted with the application of demographic corrections. Diagnostic efficiency statistics are presented, and future research directions are discussed.

Clinical Utility of Demographically Corrected WAIS-III Subtest Scores After Traumatic Brain Injury

The present study explored the diagnostic accuracy of demographically corrected norms for the Wechsler Adult Intelligence Scale–Third Edition (WAIS-III) in a diverse sample of 57 patients with traumatic brain injury (TBI) and a matched group of 61 pseudoneurologic controls. The use of demographic corrections did not significantly improve the sensitivity or specificity of WAIS-III subtest scores to TBI relative to traditional age-corrected norms. Overall classification rates were quite good for both normative systems. Although the demographic corrections attenuate ethnicity differences on the subtest scores of TBI patients, the updated norms are no more or less beneficial than traditional age-corrected norms for neurodiagnostic purposes.

The MATRICS Consensus Cognitive Battery, Part 2: Co-Norming and Standardization

The consensus cognitive battery developed by the National Institute of Mental Health's (NIMH's) Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) initiative includes 10 independently developed tests that are recommended as the standard battery for clinical trials of cognition-enhancing interventions for schizophrenia. To facilitate interpretation of results from the MATRICS Consensus Cognitive Battery using a common scaling across tests, normative data were obtained from a single representative U.S. community sample with the battery administered as a unit. The MATRICS Consensus Cognitive Battery was administered to 300 individuals from the general community at five sites in differing geographic regions. For each site, recruitment was stratified by age, gender, and education. A scientific survey sampling method was used to help avoid sampling bias. The battery was administered in a standard order to each participant in a single session lasting approximately 60 minutes. Descriptive data were generated, and age, gender, and education effects on performance were examined. Prominent age and education effects were observed across tests. The results for gender differed by measure, suggesting the need for age and gender corrections in clinical trials. The MATRICS Consensus Cognitive Battery components were co-normed, with allowance for demographic corrections. Co-norming a battery such as the MATRICS Consensus Cognitive Battery, comprising tests from independent test developers each with their own set of norms, facilitates valid interpretation of test scores and communication of findings across studies. These normative data will aid in estimating the magnitude of change during clinical trials of cognition-enhancing agents and make it possible to derive more directly interpretable composite scores.

HIV suppression by HAART preserves cognitive function in advanced, immune-reconstituted AIDS patients

HIV can damage neurons leading to cognitive impairment. Epidemiological observations suggest that neuropsychological impairment might progress despite successful HAART therapy, but available prevalence estimates are based on populations that were selected for impairment. Of 433 advanced AIDS patients with documented immune reconstitution (CD4 lymphocyte counts < 50 before and > 100 cells/microl after HAART), 286 had brief assessments of cognition (Trailmaking A/B and Digit Symbol Tests) at least once, no confounding neurological conditions, and available neuropsychological norms with comprehensive demographic corrections. At entry, most were immune reconstituted on HAART (median CD4 cell count 230 cells/microl) and HIV was suppressed (65% < 500; only 14% > 20 000 RNA copies/ml). Over one quarter (27%) of participants exhibited impairment at their initial neuropsychological assessment, a rate nearly twice that expected in a normal (HIV-uninfected) reference population (14%). These impaired participants did not differ from the unimpaired group with respect to age, sex, education, race, CD4 lymphocyte counts, or HIV-RNA levels. Improved performance on neuropsychological tests was documented over a 2-year period 3-5 years after initiating HAART. This improvement was marginally associated with the continued or improving control of plasma HIV-RNA levels, but not with concurrent levels of immune recovery (CD4 lymphocyte counts). Most advanced AIDS patients responding to HAART for prolonged periods have stable or improving cognition, but remain more likely to be impaired than the general population. During HAART, improving test performance probably reflects both practice effects and continuing neurological recovery after more than 3 years of HAART.

Demographically corrected norms for the Brief Visuospatial Memory Test-revised and Hopkins Verbal Learning Test-revised in monolingual Spanish speakers from the U.S.–Mexico border region

The large number of primary Spanish speakers both in the United States and the world makes it imperative that appropriate neuropsychological assessment instruments be available to serve the needs of these populations. In this article we describe the norming process for Spanish speakers from the U.S.–Mexico border region on the Brief Visuospatial Memory Test-revised and the Hopkins Verbal Learning Test-revised. We computed the rates of impairment that would be obtained by applying the original published norms for these tests to raw scores from the normative sample, and found substantial overestimates compared to expected rates. As expected, these overestimates were most salient at the lowest levels of education, given the under-representation of poorly educated subjects in the original normative samples. Results suggest that demographically corrected norms derived from healthy Spanish-speaking adults with a broad range of education, are less likely to result in diagnostic errors. At minimum, demographic corrections for the tests in question should include the influence of literacy or education, in addition to the traditional adjustments for age. Because the age range of our sample was limited, the norms presented should not be applied to elderly populations.

A total score for the CERAD neuropsychological battery

To develop a total or composite score for the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) neuropsychological battery. CERAD total scores were obtained by summing scores from the individual CERAD subtests (excluding the Mini-Mental State Examination [MMSE]) into a total composite (maximum score = 100). The method of tabulating the total score was constructed using normal controls (NCs; n = 424) and patients with AD (n = 835) from the CERAD registry database. The utility of the total score was further tested in independent samples of mild AD (n = 95), mild cognitive impairment (MCI; n = 60), and NC (n = 95) subjects. The CERAD total score was highly accurate in differentiating NC and AD subjects in the CERAD registry. Age, gender, and education effects were observed, and demographic correction scores were derived through multiple regression analysis. Demographically corrected CERAD total scores showed excellent test-retest reliability across samples (r = 0.95) and were highly correlated with the MMSE (r = 0.89) and Clinical Dementia Rating Scale (r = -0.83) in mixed AD and NC samples and with the Blessed Dementia Rating Scale in an AD sample (r = -0.40). The CERAD total score was highly accurate in differentiating independent samples of NC, MCI, and AD subjects. Results provide support for the validity of a Consortium to Establish a Registry for Alzheimer's Disease (CERAD) total score that can be used along with the normative data to provide an index of overall level of cognitive functioning from the CERAD neuropsychological battery.

Mayo's Older African Americans Normative Studies: Norms for Boston Naming Test, Controlled Oral Word Association, Category Fluency, Animal Naming, Token Test, Wrat-3 Reading, Trail Making Test, Stroop Test, and Judgment of Line Orientation

ABSTRACT Normative data for older African Americans are presented for several clinical neuropsychological measures, including Boston Naming Test, Controlled Oral Word Association, Category Fluency, Token Test, WRAT-3 Reading, Trail Making Test, Stroop Color and Word Test, and Judgment of Line Orientation. Age-adjusted norms were derived from a sample of 309 cognitively normal, community-dwelling individuals, aged 56 through 94, participating in Mayo's Older African Americans Normative Studies (MOAANS). Years of education were modelled on age-scaled scores to derive regression Equations that may be applied for further demographic correction. These data should enhance interpretation of individual test performances and facilitate analysis of neuropsychological profile patterns in older African American patients who present for dementia evaluations.

A Brief Report on WAIS-R Normative Data Collection in Mayo's Older African Americans Normative Studies

ABSTRACT Historically, neuropsychological measures such as the Wechsler Adult Intelligence Scale-Revised (WAIS-R) have yielded unacceptably high rates of misdiagnosis of impairment among cognitively normal African Americans, primarily due to poor test specificity and inadequate representation of ethnic minorities in the normative sample. In this report, we briefly review these issues and describe efforts by investigators in Mayo's Older African Americans Normative Studies (MOAANS) to develop more appropriate norms for African American elders on the WAIS-R. During MOAANS data collection, the third edition of the WAIS (WAIS-III) was introduced with updated representation of ethnic minorities in the normative database. More recently, specific demographic corrections for African Americans have been derived for WAIS-III subtest scores and indices. As such, WAIS-R normative estimates are not presented here. Interested readers who wish to obtain a full set of MOAANS WAIS-R norms, however, are invited to contact the authors for these data.

Norms for letter and category fluency: demographic corrections for age, education, and ethnicity.

Letter and category fluency tasks are used to assess semantic knowledge, retrieval ability, and executive functioning. They appear to be useful in detecting different types of dementia, but accurate detection of neuropsychological impairment relies on appropriate normative data. Multiple regression analysis was used to develop demographically corrected norms for letter and category fluency in 768 normal adults. T-score equations were developed on a base subsample of 403, and crossvalidated on a separate subsample (n = 365). Participants ranged in age from 20 years to 101 years; in educational level from 0 to 20 years; 55% were Caucasian and 45% were African American. Together, age, education, and ethnicity were significant predictors of letter and category fluency performance, accounting for 15% and 25% of variance, respectively. Formulas and tables for converting raw fluency scores to demographically corrected T scores are presented.

Prediction of Brain Damage Severity: Demographic Corrections

This study investigated the value of using age and education corrections to the Alternative Impairment Index (All), to predict the severity of brain damage on the General Neuropsychological Deficit Score (GNDS) and the Halstead Impairment Index (HII). A sample of 40 normal, psychiatric and brain-damaged subjects who had been administered the HRNTB was obtained and the AII, GNDS and HII were calculated for each subject. Hit rates for agreement on level of severity, after correction for age and education effects, for the GNDS and All were 52.5% and for the All and HII were 47.5%. Examination of the data suggested that All, after correction for age and education effects, reflects severity of brain damage at a chance level on both the HII and on the GNDS.

Scoring methodology: Demographic corrections in neuropsychological assessment

Scoring methodology: Demographic corrections in neuropsychological assessment

Prediction of brain damage severity: Demographic corrections

This study investigated the value of using age and education corrections to the Alternative Impairment Index (All), to predict the severity of brain damage on the General Neuropsychological Deficit Score (GNDS) and the Halstead Impairment Index (HII). A sample of 40 normal, psychiatric and brain-damaged subjects who had been administered the HRNTB was obtained and the AII, GNDS and HII were calculated for each subject. Hit rates for agreement on level of severity, after correction for age and education effects, for the GNDS and All were 52.5% and for the All and HII were 47.5%. Examination of the data suggested that All, after correction for age and education effects, reflects severity of brain damage at a chance level on both the HII and on the GNDS.

Prediction of brain damage severity: Demographic corrections

Prediction of brain damage severity: Demographic corrections

Composite neuropsychological batteries and demographic correction: Standardization based on equivalent scores, with a review of Published Data

Equivalent Scores (ES; Capitani & Laiacona, 1988) is a 5-point scale that offers a solution to the problem of standardizing neuropsychological scores after adjustment for age and education, given that the common standardization is not generally applicable in these cases. ES are discussed, and their properties and limits are compared with those of z-standardization. In a battery of ES-standardized tests, the average ES (AES) for the whole battery can provide a measure of the overall cognitive level, free of the influence of age and education. We report empirical data from a battery composed of 10 ES-standardized tests, in order to discuss general properties of ES standardization. The expected mean of the AES is constant, regardless of the number or type of tests included. The standard deviation of the AES, however, is variable: it decreases in proportion to the number of tests, but increases in proportion to their intercorrelation. We provide general indications concerning the normality threshold, which are applicable to all batteries of ES-standardized tests regardless of the number and type.

Development and validation of a demographic correction system for neuropsychological measures used in the Canadian Study of Health and Aging.

(1996). Development and validation of a demographic correction system for neuropsychological measures used in the Canadian study of health and aging. Journal of Clinical and Experimental Neuropsychology: Vol. 18, No. 4, pp. 479-616.