Clinical Validation of the General Ability Index—Estimate (GAI-E): Estimating Premorbid GAI

Core Neuropsychological Measures for Obesity and Diabetes Trials: Initial Report

Obesity and diabetes are known to be related to cognitive abilities. The Core Neuropsychological Measures for Obesity and Diabetes Trials Project aimed to identify the key cognitive and perceptual domains in which performance can influence treatment outcomes, including predicting, mediating, and moderating treatment outcome and to generate neuropsychological batteries comprised of well-validated, easy-to-administer tests that best measure these key domains. The ultimate goal is to facilitate inclusion of neuropsychological measures in clinical studies and trials so that we can gather more information on potential mediators of obesity and diabetes treatment outcomes. We will present the rationale for the project and three options for the neuropsychological batteries to satisfy varying time and other administration constraints. Future directions are discussed. Preprint version of the document is available at https://osf.io/preprints/nutrixiv/7jygx/.

Cognitive disturbances in primary blepharospasm

The common belief that primary dystonia is a purely motor disorder with no anatomical substrate and no other accompanying neurological dysfunction has recently been challenged. In addition, there is increasing evidence that the basal ganglia besides motor control, plays a role in cognitive functioning. However, no systematic cognitive performance evaluation has been carried out in patients with primary blepharospasm (BS), one of the most common forms of adult dystonia. We evaluated a series of 20 patients with primary BS and a group of 17 controls matched by severity of mood symptoms, age, and sex. BS patients performed significantly worse on the Luria sequencing test, Purdue pegboard test, reciprocal coordination, tactile denomination, and reverse visuospatial span and the differences persisted after correction for age, duration of disease, severity of BS, and degree of depression. The Wisconsin card sorting test showed no statistical difference, but BS patients made more errors and more perseverative answers than expected according to population means, whereas the control group performed poorly but within normal parameters. Our findings suggest broad cortical involvement in focal dystonia that is not correlated with the severity or duration of dystonia.

Using an implicit memory task to estimate premorbid memory

Clinicians are often asked to determine if significant memory loss has occurred. Clinical judgment figures prominently in making these determinations, because there is no accepted, objective method for estimating premorbid memory. Two studies were designed to explore the utility of an implicit memory task, Anagrams Solutions, for estimating premorbid memory ability. A secondary goal was to identify predictors of immediate and delayed memory measured by the Repeatable Battery for the Assessment of Neuropsychological Status using selected intellectual (IQ) and demographic variables. Participants in both studies were administered the implicit memory task, explicit memory measures, and IQ estimate. Results revealed that Anagrams Solutions was not a useful estimate of premorbid memory and that a combination of IQ and demographic variables accounted for 24-31% of the variance in measured memory performances. Findings point to the need for caution in interpreting scores on these variables as valid estimates of premorbid memory functioning.

A proposed method to estimate premorbid full scale intelligence quotient (FSIQ) for the Canadian Wechsler Intelligence Scale for Children–Fourth Edition (WISC-IV) using demographic and combined estimation procedures

Establishing a comparison standard in neuropsychological assessment is crucial to determining change in function. There is no available method to estimate premorbid intellectual functioning for the Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV). The WISC-IV provided normative data for both American and Canadian children aged 6 to 16 years old. This study developed regression algorithms as a proposed method to estimate full-scale intelligence quotient (FSIQ) for the Canadian WISC-IV. Participants were the Canadian WISC-IV standardization sample (n = 1,100). The sample was randomly divided into two groups (development and validation groups). The development group was used to generate regression algorithms; 1 algorithm only included demographics, and 11 combined demographic variables with WISC-IV subtest raw scores. The algorithms accounted for 18% to 70% of the variance in FSIQ (standard error of estimate, SEE = 8.6 to 14.2). Estimated FSIQ significantly correlated with actual FSIQ (r = .30 to .80), and the majority of individual FSIQ estimates were within +/-10 points of actual FSIQ. The demographic-only algorithm was less accurate than algorithms combining demographic variables with subtest raw scores. The current algorithms yielded accurate estimates of current FSIQ for Canadian individuals aged 6-16 years old. The potential application of the algorithms to estimate premorbid FSIQ is reviewed. While promising, clinical validation of the algorithms in a sample of children and/or adolescents with known neurological dysfunction is needed to establish these algorithms as a premorbid estimation procedure.

Examining the relationship between WAIS-III premorbid intellectual functioning and WMS-III memory ability to evaluate memory impairment

The purpose of this study was to extend previous research by Lange and Chelune (2006) by evaluating the clinical utility of GAI-memory discrepancy scores to detect memory impairment using estimated premorbid GAI scores (i.e., GAI-E) rather than obtained GAI scores. Participants were 34 patients with Alzheimer's-type dementia and a sub-sample of 34 demographically matched participants from the WAIS-III/WMS-III standardization sample. GAI-memory discrepancy scores were more effective at differentiating Alzheimer's patients versus healthy controls when using estimated premorbid GAI scores than obtained GAI scores. However, GAI(E)-memory discrepancy scores failed to provide unique interpretive information beyond that which is gained from interpretation of the memory index scores alone. This was most likely due to the prevalence of obvious memory impairment in this patient population. Future research directions are discussed.

Estimating premorbid general cognitive functioning for children and adolescents using the American Wechsler Intelligence Scale for Children-Fourth Edition: demographic and current performance approaches

Neuropsychologic evaluation requires current test performance be contrasted against a comparison standard to determine if change has occurred. An estimate of premorbid intelligence quotient (IQ) is often used as a comparison standard. The Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) is a commonly used intelligence test. However, there is no method to estimate premorbid IQ for the WISC-IV, limiting the test's utility for neuropsychologic assessment. This study develops algorithms to estimate premorbid Full Scale IQ scores. Participants were the American WISC-IV standardization sample (N = 2172). The sample was randomly divided into 2 groups (development and validation). The development group was used to generate 12 algorithms. These algorithms were accurate predictors of WISC-IV Full Scale IQ scores in healthy children and adolescents. These algorithms hold promise as a method to predict premorbid IQ for patients with known or suspected neurologic dysfunction; however, clinical validation is required.