Estimation of premorbid intellectual functioning is an essential part of interpreting neuropsychological performance following brain injury and disease. Oftentimes prior neuropsychological assessment is non-existent, which necessitates the use of premorbid indicators to determine the presence or degree of injury or disease-induced impairment. The neuropsychological research literature has studied various estimation methods including the “best performance” method, the use of actuarial or demographic regression formulas, and measuring cognitive functions assumed to be resistant to disease or injury. The latter method includes assessing reading ability to predict premorbid functioning.
Using reading level as a premorbid indicator is predicated on reading’s high correlation with IQ in the general population, its greater resistance to dementia than vocabulary tests, and its supposed reliance on previous knowledge rather than current cognitive functioning (Franzen, Burgess, & Smith-Seemiller, 1997
; Nelson & McKenna, 1975
). Several reading tasks have been studied including The National Adult Reading Test (NART) (Nelson & McKenna, 1975
), The North American Adult Reading Test (NAART) (Spreen & Strauss, 1991
), and versions of the Wide Range Achievement Test – Reading Recognition subtest (WRAT) (Jastak & Wilkinson, 1984
). The WRAT Reading subtest unlike the NART (or NAART) includes regularly, as well as irregularly, spelled words. The WRAT Reading subtest is routinely used for assessing premorbid intelligence because it is well normed and easy to administer. It also provides a corresponding grade level for reading ability.
The National NeuroAIDS Tissue Consortium (NNTC) is a multi-site, longitudinal observational study of advanced HIV patients that utilizes a comprehensive neuropsychological battery and includes the WRAT-3 Reading subtest to estimate premorbid intelligence (Woods et al., 2004
). Within this consortium, the Manhattan HIV Brain Bank (MHBB) site has a predominantly racial/ethnic minority cohort in which 41% of its participants have <an eighth-grade reading level and 56% have reading levels which are ≥2 years lower than their stated educational level (Ryan et al., 2005
). Thus, it provides a laboratory in which the effects of neurologic disease on a low-literacy cohort can be examined. In the MHBB cohort we have observed individuals whose performance on the WRAT-3 Reading subtest is indicative of premorbid intellectual functioning in the mentally retarded range despite clinical presentations, as well as work and social histories, that are not suggestive of mental retardation (nor do these individuals report dyslexia, remedial reading, or any other condition that could account for a very low reading level). Thus, we suspect that a poor quality of education is responsible for very low reading levels in this cohort, and sought to assess intellectual functioning using a measure that would be less dependent on verbal abilities or education.
The MHBB is not the only group in which discrepancy in education and reading levels has been reported; it has been seen in research settings with other racial/ethnic minority cohorts (Manly, Jacobs, Touradji, Small, & Stern, 2002
; O’Bryant, Schrimsher, & O’Jile., 2005
; O’Bryant et al., 2007
). These studies have led to a suggestion that reading ability should be used as a proxy for educational level (Manly et al., 2002
). While reading ability is likely to be a better approximation of the number of years of education completed for racial/ethnic minorities, it may also have limitations in completely eradicating neuropsychological test biases, and addressing the issue of estimating premorbid intelligence.
Foremost among these limitations is the fact that reading ability has a variable relationship to intellectual functioning across racial/ethnic populations, and that there is over-representation of racial/ethnic minorities at the lowest levels of literacy (NCES, 2007). For racial/ethnic minorities, educational inequities (i.e., teacher training, school district spending on students, and student/teacher ratio, etc.) are confounded with reading ability. Given inequities in educational quality and funding, reading ability does not appear to have the same relationship to intellectual functioning in racial/ethnic minorities that has been reported in predominantly non-Hispanic White samples (Johnstone et al., 1996; Wiens, Bryan, & Crosson, 1993
). Race/ethnicity has been found to be a significant predictor of the relationship between reading and IQ, and adds incrementally more variance to the model (beyond the WRAT Reading subtest) (Kareken, Gur, & Saykin, 1995
). The incremental variance that race/ethnicity contributes to the relationship between reading and IQ likely reflects access to a quality education; a factor that can differ by race/ethnicity but is due to sociopolitical forces. Thus, while using educational level may be biased toward overestimating racial/ethnic minorities’ abilities, using reading level could potentially underestimate abilities for some, given inadequate teaching resources. Use of a test that is less dependent on education would be ideal in understanding expected neuropsychological functioning in individuals with low literacy.
The General Ability Measure for Adults (GAMA) assesses intellectual functioning using abstract designs, thereby limiting reliance on verbal comprehension (Naglieri & Bardos, 1997
). It was specifically designed for individuals with limited educational experiences and/or verbal skills. Given these features of the GAMA, it may be an appropriate measure of intellectual functioning for a racially and ethnically diverse urban cohort who have likely experienced a poor quality of education.
The GAMA consists of four types of problems: matching, reasoning by analogy, sequencing, and mental construction. “Matching” requires the individual to choose which of six options is identical to the target stimulus in shape, color, and configuration. “Analogies” demands that the individual recognize the relationship between two figures and then determine which of six options mimics the same conceptual relationship to the target stimulus. In “Sequences” the color, shape, and location of the abstract design changes in a logical sequence. The individual must understand the pattern of change and choose the option that fits the pattern. “Construction” has the individual decide how several target shapes can be put together to produce one of the six options. Thus, the individual has to analyze and synthesize the spatial characteristics of the target shapes to mentally construct the correct design.
The psychometric properties of the GAMA reveal adequate internal consistency, as well as test–retest reliability. Validity studies revealed that individuals performed similarly on the GAMA as on other tests of intellectual functioning (Naglieri & Bardos, 1997
). GAMA correlated .74 with WAIS-R PIQ, .65 with WAIS-R VIQ, and .75 with WAIS-R FSIQ. Notably, these correlations are higher than those of the WRAT-3 Reading subtest with the WAIS-R (despite similar racial/ethnic composition in the normative groups). The WRAT-3 manual reports that the reading subtest correlated .63 for WAIS-R VIQ, .31 for PIQ, and .53 for FSIQ (Wilkinson, 1993
Both the WRAT-3 and the GAMA were standardized to match the 1990 US Census. The WRAT-3 standardization sample was comprised of 49.3% women and 50.7% men; the GAMA had 54.3% women and 45.7% men. The racial/ethnic composition of the GAMA and the WRAT-3 normative groups were similar. Racial/ethnicity breakdown was 71.7% White, 13.6% African American, 10.7% Hispanic, and 3.9% Other for the WRAT-3; and 76.3% White, 12.5% African American, 7.8% Hispanic, and 3.4% Other for the GAMA. Age groups for the WRAT-3 varied from age 5 to age 75 whereas the GAMA ranged from 18 to 96 years. While the WRAT-3 did not stratify by education level, the GAMA included five educational levels (less than 9 years education completed, 9–12 years completed without graduating, high school graduate or GED, some college including vocational programs and 2-year colleges, and a bachelor’s degree or more). The WRAT-3 test manual states that the standardization sample is representative of the US population with regard to SES whereas the GAMA makes no mention of SES characteristics of its normative sample.
Using a cross-sectional design, the present study examined the comparability of the GAMA and the WRAT-3 Reading subtest among a predominantly racial/ethnic minority cohort with advanced HIV disease. The study’s aim was to determine how the GAMA performed relative to the WRAT-3 Reading test at varying levels of literacy, and also to examine how the GAMA and the WRAT-3 Reading test related to neuropsychological domains at different levels of literacy. We hypothesized that participants with low literacy would perform better on the GAMA than on the WRAT-3 Reading subtest, and that the GAMA would more strongly correlate with neuropsychological functioning than the WRAT-3 among a cohort characterized by low literacy. Additionally, we hypothesized that participants with low literacy (WRAT-3 reading scores<80 SS), but GAMA scores within normal limits (>80 SS), would perform better on neuropsychological domains than individuals whose performance was low (<80 SS) on both tests.