Intellectual loss in Alzheimer's dementia and WAIS-R intrasubtest scatter

Wais—r Scatter with Psychiatric Inpatients: II. Intersubtest Scatter,

Intersubtest scatter values for the Full, Verbal, and Performance Scales of the WAIS—R were estimated for a sample of 163 psychiatric inpatients and compared with those reported for the WAIS—R standardization group using the normal deviate (z) test. Intersubtest scatter was assessed using the range and the Profile Variability Index. Results were surprising and conflicted with what was expected based on the clinical literature. First, in comparison to the standardization group, the psychiatric inpatients showed significantly more intersubtest scatter on the Verbal Scale only, while Performance Scale values were comparable. Second, the psychiatric inpatient sample, as a group, showed identical amounts of scatter on the Verbal and Performance Scales. Results suggest that the interpretation of intersubtest scatter as a sign of psychopathology should be avoided.

Relationship of IQ to verbal learning and memory: test and retest

The relationship between Wechsler Adult Intelligence Scale-Revised (WAIS-R) IQ and performance on measures of memory was examined in 64 adults tested twice at a 2-week interval. Repeated measures analyses of variance revealed that individuals with Low-Average WAIS-R Full Scale IQ scores performed significantly more poorly than did individuals with Average and High-Average Full Scale IQs on memory measures including the Wechsler Memory Scale-Revised (WMS-R) General Memory and Delayed Recall indices, as well as California Verbal Learning Test (CVLT) Total Words. Learning Slope, and Discriminability. Although all three groups demonstrated significant practice effects on each memory measure, group differences in performance persisted at retest. Multiple regression analyses revealed that WAIS-R factor scores Verbal Comprehension and Freedom from Distractibility accounted for up to 42% of the variance in WMS-R and CVLT indices. Moreover, WAIS-R performance at initial testing accounted for 22-41% of the variance in memory performance at retest. These results are discussed in the context of the construct stabilities of intelligence and memory, as well as the psychometric precision of the tests used to measure these constructs.

Age-related prefrontal alterations during auditory memory

Event-related potentials were recorded from young and elderly subjects while they performed a modified auditory Sternberg memory task. Aging was associated with a decrease in frontal activation, suggesting that prefrontal alterations may be central to age-related impairments in auditory working memory. Young subjects showed significant serial position effects electrophysiologically, while elderly subjects showed no recency effects for P3 latency and no serial position effects for N4 and SFN amplitude. This finding, in combination with increased false alarm rates in the elderly, suggest that the two group of subjects employed different cortico-limbic circuits to perform the task.

Base rates of the WAIS-R intersubtest scatter and VIQ-PIQ discrepancy in normal elderly

This study provides base rates for WAIS-R VIQ-PIQ discrepancy and for 3 indices of intersubtest scatter in a sample of high functioning normal elderly. High correlations between indices of scatter, such as (1) range of scatter; (2) Profile Variability Index; and (3) number of subtest scores that significantly deviated from the individual's own mean, indicate that easy-to-compute range can be used as an adequate measure of scatter in many clinical settings. The results suggest that bright elderly individuals display a large degree of scatter. The clinician should base judgment regarding abnormality of the WAIS-R indices on the rarity of the value demonstrated by the individual with respect to the sample of comparable age and intelligence level.

WAIS-R item difficulties with psychiatric inpatients

Item difficulties for 10 WAIS-R subtests were determined for a sample of psychiatric inpatients (N = 150). Spearman correlation coefficients between psychiatric inpatient and standardization group rank orders were large and significant across all subtests except Object Assembly, which demonstrates the expected trend of increasing item difficulty for the psychiatric inpatient sample. Using linear regression, items with standardized residuals greater than two were judged to be significantly out of order for the psychiatric inpatient sample. Of the 165 WAIS-R items examined in this study, only 7 were found to be out of order. This result may have been due to chance and suggests that, in general, WAIS-R subtest item difficulty curves for psychiatric inpatients and the WAIS-R standardization group are comparable.

WAIS-R scatter with psychiatric inpatients: I Intrasubtest scatter

Intrasubtest scatter values for eight WAIS-R subtests were estimated for a sample of 150 psychiatric inpatients and compared with those reported for a comparable portion of the WAIS-R standardization group by Kaplan, Fein, Morris, and Delis in 1991, using the normal deviate (z) test. The standardization group's intrasubtest scatter was significantly greater than those reported for the psychiatric inpatients on all subtests except Arithmetic and Information. These results suggested that, contrary to expectation, limited intrasubtest scatter may characterize WAIS-R protocols of psychiatric inpatients, while the presence of scatter may characterize normal WAIS-R performance.