Factor structure of the wechsler memory scale-revised

Abstract

The factor structure of the Wechsler Memory Scale-Revised (WMS-R) was examined in a large (N = 434) sample of patients referred to the neuropsychology laboratories of two large medical centers. The subtests of the WMS-R were subjected to principal-components factor analysis. Some analyses included only the immediate-recall subtests, while other analyses included both immediate-and delayed-recall subtests. Additional analyses included VIQ and PIQ from the WAIS-R. Initial analyses of immediate-recall subtests indicated a two-factor solution similar to that reported in the standardization sample. Inclusion of IQ scores also revealed a two-factor solution with IQ scores and most memory subtests loading on separate factors. Inclusion in the analysis of delayed-recall subtests revealed three-factor solution with factors interpreted as representing verbal memory, nonverbal memory, and attention/IQ. These results are discussed in terms of factor-analytic studies of the earlier Wechsler Memory Scale, and the implications of the current data for research and clinical practice.     

Confirmatory factor analysis of the wechsler memory scale-revised in a sample of head-injured patients

Abstract

As part of a standard evaluation of neuropsychological sequelae, the Wechsler Memory Scale-Revised (WMS-R) was administered to 107 patients with a history of traumatic brain injury. Confirmatory factor analyses were conducted on the 12 subtests of the WMS-R to examine the fit of various hypothesized factor patterns, including patterns identified in previous exploratory factor analytic studies. Because part of the correlation between immediate and delayed recall trials of the same material is attributable to a common measurement procedure, this correlation due to measurement commonality was partialled out of the conceptual factor structure. The results suggested the presence of 3 distinct but highly correlated factors: attention/concentration, immediate memory, and delayed recall. Models that posited separate verbal and nonverbal memory processes failed to improve fit over more parsimonious models. Comparisons with previous factor analytic studies and implications for clinical assessment are discussed.     

Confirmatory factor analysis of the Wechsler Memory Scale-Revised in a sample of head-injured patients

As part of a standard evaluation of neuropsychological sequelae, the Wechsler Memory Scale-Revised (WMS-R) was administered to 107 patients with a history of traumatic brain injury. Confirmatory factor analyses were conducted on the 12 subtests of the WMS-R to examine the fit of various hypothesized factor patterns, including patterns identified in previous exploratory factor analytic studies. Because part of the correlation between immediate and delayed recall trials of the same material is attributable to a common measurement procedure, this correlation due to measurement commonality was partialled out of the conceptual factor structure. The results suggested the presence of 3 distinct but highly correlated factors: attention/concentration, immediate memory, and delayed recall. Models that posited separate verbal and nonverbal memory processes failed to improve fit over more parsimonious models. Comparisons with previous factor analytic studies and implications for clinical assessment are discussed.     

Confirmatory analysis of the factor structure of the wechsler memory scale-revised

Abstract

Memory functions are known to be multifaceted. Models of the dimensionality of memory, as measured by the Wechsler Memory Scale-Revised (WMS-R), were investigated. Confirmatory factor analysis was used to explore one-, two-, and three-factor models for the first eight subtests of the WMS-R given to normal subjects in the standardization sample (N = 316) and a heterogeneous sample of clinical subjects (N = 343). The best fitting model was a two-factor model with general memory and attention/concentration dimensions.     

Factor analysis of the wechsler memory scale-revised and the halstead-reitan neuropsychological battery

A principal components factor analysis of the 12 subtests of the WMS-R, WAIS Verbal and Performance IQ scores, and measures of a modified Halstead-Reitan Neuropsychological Battery was performed on a sample of 135 patients. The Visual Reproduction subtests I and II factored with other spatial measures and Performance IQ while Logical Memory I and II and Verbal Paired Associates I and II emerged as separate verbal memory factors. Additionally, two attention/concentration factors were found, one primarily verbal and one primarily visual. Further study in the interpretation of the Verbal and Visual Memory Indexes was advised.     

A prorating system for the wechsler memory scale-revised

Various sensory and motor impairments may render a patient unable to complete certain subtests on the Wechsler Memory Scale-Revised (WMS-R). Consequently, when a subtest is missing from the battery, the clinician is unable to obtain one or more of the summary indices typically provided by the WMS-R. The present study used a mixed clinical sample (N = 300) to derive regression weights that may be used to predict a patient's performance on each of the WMS-R memory indices when a subtest is missing. The relative contributions of each subtest to the scale with which it is associated and the predictive accuracy of the regression equations are discussed.     

Validation of the Wechsler Memory Scale-Revised in a Sample of People with Intractable Temporal Lobe Epilepsy

Summary: Purpose: The Wechsler Memory Scale-Revised (WMS-R) is used routinely for presurgical assessment of memory for patients considering elective resection of the temporal lobe and/or hippocampus for the relief of intractable temporal lobe epilepsy (TLE). We investigated the validity of the WMS-R in a population of people with TLE.
Methods: The sample consisted of 138 patients with a diagnosis of TLE in which the epileptogenic focus was clearly and exclusively lateralized to either the right or left hemisphere. They underwent a complete neuropsychological examination as a routine part of their investigation for epilepsy surgery. Psychometric scores included in this study were: Wechsler Adult Intelligence Scale-Revised (WAIS-R) I.Q. scores, National Adult Reading Test Revised (NART-R) predicted-I.Q. scores, and WMS-R Memory Index and subtest scores.
Results: Multiple univariate analyses were performed. The group with left temporal focus had significantly lower Verbal Memory Index, Logical memory (both immediate and delayed), and Digit Span scores. Visual/Verbal discrepancy scores incorrectly identified most patients with right temporal focus. Analyses of a total group of people with epilepsy (i.e., mixed temporal, frontal, occipital and unknown foci) as compared with the normative sample indicated that the patient group scored significantly lower across all memory index scores and most memory subtests.
Conclusions: Our results confirm that the WMS-R is capable of lateralizing to left hemispheric impairment but is more problematic in the assessment of right hemispheric impairment. The Visual/Verbal Memory Index discrepancy has questionable validity. People with epilepsy performed less well on the WMS-R than did the normative sample. The need for reliable and valid nonverbal tests of memory is therefore warranted.     

Severity of Impairment or Specific Types of Aphasia: An Empirical Investigation

This study examined empirical means of clustering aphasic patients into relatively homogenous and identifiable groups. The method included: (1) examining the intercorrelations of the subtests of the Neurosensory Comprehensive Examination for Aphasia by the means of factor analysis; (2) allowing the subjects to group themselves in homogenous subgroups by means of hierarchical cluster analysis; and (3) comparing the profiles of these groups on the derived dimensions. Four factors accounting for 79.3% of the total test variance were derived which reflected attention/memory; reading ability; verbal-naming ability; and elementary writing skills. With five groups the hierarchical grouping analysis indicated that only 21.5% of the total variability could be ascribed to within group variability. An analysis of variance of the four factor scores found that 66%, 93%, 81% and 79% of the between group variance of each of the respective factors was associated with group membership and the accuracy of membership prediction was 94.1%. Four groups appeared to be distributed on the basis of a severity model of impairment. One group representing 6.3% of the total sample demonstrated a pattern of specific impairment involving a mild level of impairment on attention/memory tasks, a moderate level of impairment on verbal naming tasks and writing skills, and a profound level of impairment on measures of reading skills. The high inter-factor correlations indicated the general nature of language functioning. The results were discussed in terms of the concept of aphasia as a general cognitive deficit.     

Cognitive impairment or inadequate norms? A study of healthy,rural, older adults with limited education

Abstract

This study established preliminary norms for nine commonly administered neuropsychological tests for a biracial sample (N = 133; White = 64, African American = 69) of nondemented, rural community-dwelling elders (mean age = 76.48; SD = 7.87) with 10 or fewer years of formal education (mean education = 6.65 years; SD = 2.14). Hierarchical multiple regression analyses revealed that education was an important predictor of performance on the Mini-Mental State Examination (MMSE), Mattis Dementia Rating Scale (MDRS), Clock Drawing, Ravens' Colored Progressive Matrices, Wechsler Adult Intelligence Scale-Revised (WAIS-R) Vocabulary and Block Design, Verbal Fluency (Category) and Logical Memory and Visual Reproduction subtests from the Wechsler Memory Scale-Revised (WMS-R), but did not predict scores on the Fuld Object Memory Evaluation or memory savings scores from the WMS-R. Race was a predictor only for WAIS-R Vocabulary and Block Design, and WMS-R Logical Memory Delayed. Approximately half of the subjects scored below the published cut-offs for the MMSE and MDRS and would have been considered mildly to moderately impaired on many of the test measures.     

Convergent and Discriminant Validity of the CVLT (Dementia Version)

This study investigated the convergent and discriminant validity of the 9-item “dementia version” of the California Verbal Learning Test (CVLT-9) in a sample of 130 geriatric patients evaluated for memory complaints. Moderate correlations were observed between the CVLT-9 sum of words recalled for trials 1–5 (Trial 1–5 Recall) and Long-Delay Free Recall (LDFR) measures and the immediate and delayed Logical Memory (LM I and LM II) and Visual Reproduction (VR I and VR II) subtests from the Wechsler Memory Scale-Revised (WMS-R). However, the CVLT-9 Trial 1–5 Recall and VR I measures demonstrated significant correlations with a number of additional measures of language and visuospatial ability. The CVLT-9 LDFR, and the WMS-R LM I, LM II, and VR II showed less overlap with non-episodic memory functioning. A principal components analysis yielded a three-component solution consisting of a general or “g” component, a specific memory component, and a mood component. The CVLT-9 Trial 1–5 Recall and VR I loaded on both the “g” and the memory components, whereas LM I, LM II, and VR II loaded on only the memory component. We conclude that the CVLT-9 Trial 1–5 Recall and VR I demonstrate low discriminant validity, suggesting diminished specificity as memory measures.     

Convergent and discriminant validity of the CVLT (dementia version). California Verbal Learning Test.

This study investigated the convergent and discriminant validity of the 9-item "dementia version' of the California Verbal Learning Test (CVLT-9) in a sample of 130 geriatric patients evaluated for memory complaints. Moderate correlations were observed between the CVLT-9 sum of words recalled for trials 1-5 (Trial 1-5 Recall) and Long-Delay Free Recall (LDFR) measures and the immediate and delayed Logical Memory (LM I and LM II) and Visual Reproduction (VR I and VR II) subtests from the Wechsler Memory Scale-Revised (WMS-R). However, the CVLT-9 Trial 1-5 Recall and VR I measures demonstrated significant correlations with a number of additional measures of language and visuospatial ability. The CVLT-9 LDFR, and the WMS-R LM I, LM II, and VR II showed less overlap with non-episodic memory functioning. A principal components analysis yielded a three-component solution consisting of a general or "g' component, a specific memory component, and a mood component. The CVLT-9 Trial 1-5 Recall and VR I loaded on both the "g' and the memory components, whereas LM I, LM II, and VR II loaded on only the memory component. We conclude that the CVLT-9 Trial 1-5 Recall and VR I demonstrate low discriminant validity, suggesting diminished specificity as memory measures.     

Interrater agreement on the wechsler memory scale-revised in a mixed clinical population

Logical Memory and Visual Reproduction subtests of the Wechsler Memory Scale-Revised (WMS-R) were administered as a part of a comprehensive neuropsychological test battery to 50 inpatient and outpatient male veterans (M = 52 years) with diagnoses of neurologic, alcoholic, and psychiatric conditions. Tests were scored blindly by two trained examiners and kappa values were reported for Logical Memory text, and individual scoring criteria for Visual Reproductions. Almost perfect interrater agreement beyond chance was generally observed, thus replicating excellent interrater reliability obtained from a healthy normative sample. Mild variability (moderate agreement) on individual items is discussed.     

Factorial Invariance for Combined Wechsler Adult Intelligence Scale-Revised and Wechsler Memory Scale-Revised Scores in a Sample of Clients With Alcohol Dependency*

This study examined the joint factor structure of the WAIS-R and WMS-R in a sample of 289 participants (mostly males) with alcohol dependency. In a confirmatory phase we contrasted a range of factor models derived from previous analyses of the Wechsler scales. The best fitting model incorporated five factors representing Verbal Comprehension, Perceptual Organization, Attention-Concentration, Verbal Memory, and Visual Memory, with reassignment of factor loadings for two subtests. The invariance of the measurement model was then examined comparing data from a large sample of healthy participants (J. R. Carstairs E. A. Shores, 1999). The results indicated that the number of factors was invariant across samples, and four of the factors satisfied the criterion of partial measurement invariance.     

DIFFERENTIAL PERFORMANCE OF ALZHEIMER'S AND VASCULAR DEMENTIA PATIENTS ON A BRIEF BATTERY OF NEUROPSYCHOLOGICAL TESTS

The purpose of this article was to examine the differences in neuropsychological test performance between groups with Alzheimer's and vascular dementia. Patients included in this study were those diagnosed with Alzheimer's Disease (AD) or Vascular Dementia (VAD) through a series of neuroradiological tests that included at a minimum a CT or MRI scan and a SPECT scan. Of the 113 AD patients, the average age was 80.08 (SD = 5.91) years and average education was 12.85 (SD = 2.88). Of the 109 VAD patients, average age was 78.67 (SD = 5.35) and average education was 13.10 (SD = 2.65). Tests included selected subtests of the WAIS-R, Word Fluency, Rey Figure, Boston Naming Test, Math, Reading, and subtests from the WMS-R. Five tests showed significant differences in favor of the VAD group: Information, Similarities, Picture Completion, WRAT Mathematics, and the Boston Naming Test. Both groups did well on Reading, while both did poorly on the Rey and Word Fluency. Although both groups did poorly on memory measures, the VAD patients showed better performance. Overall, the two groups did not differ significantly on the more complex tests, but did differ on more basic tests and all the memory tests. This pattern of similar score on complex tests and different scores on basic tests demonstrates the theory that both types of dementia affected higher, more complex skills. Differences between the groups were only apparent when basic skills were compared and were not reflected in more complex and neuropsychologically “sensitive” tests.     

Performance on the Test of Everyday Attention and Standard Tests of Attention following Severe Traumatic Brain Injury

The Test of Everyday Attention (TEA) was designed to address some of the limitations of established measures of attention. However, very few studies have examined its clinical utility. A group of 35 patients who had sustained a severe TBI were compared with 35 age- and education-matched controls on the TEA, Stroop, SDMT, WMS-R Digit Span, Ruff 2s and 7s Selective Attention Test, and PASAT. Of the TEA subtests, only the Map and Telephone Search subtests of the TEA produced significant differences between the two groups, suggesting a deficit in visual selective attention following TBI. Principal components analysis revealed a four-component/factor structure of attention, largely consistent with previous studies. A logistic regression found that the TEA Map Search and Modified Colour-Word subtest of the Stroop were best able to discriminate between the TBI and control groups. When the TBI group was divided into Early (< 1 year post injury) and Late (> 2 years post injury) groups, there was an additional deficit on the Lottery (sustained attention) subtest in the Early TBI group, indicating that there is some recovery in attentional function beyond 1 year post injury.     

Psychopathology in the Dogon Plateau: an assessment using the QDSM and principal components analysis

Background: The present paper reports the findings of principal components analysis performed on the basis of answers to the Questionnaire pour le Depistage en Santé Mentale (QDSM) administered to subjects from the Bandiagara plateau (Mali), who had been evaluated in a previously published report. Methods: The study sample was made up of 466 subjects (253 males, 213 females), 273 of whom belonged to the Dogon ethnic group, 163 were Peul and the remaining 30 belonged to other groups (Sonrai, Bozo, Tuareg, Bambara). All subjects were submitted to QDSM, a structured interview derived from the Self Reporting Questionnaire. Data obtained were processed by means of principal components analysis, in order to obtain syndromic aggregations. Results: Eight factors with an Eigen value greater than 1 were extracted, which provided sufficient explanation for the overall variance observed among the 23 items. These factors may be termed as follows: Sadness (factor 1); Dysphoria (factor 2); Nightmares (factor 3); Persecution (factor 4); Somatic symptoms (factor 5); Special powers (factor 6); Hopelessness (factor 7); Loss of Interest (factor 8). Conclusions: The findings from this study support the hypothesis of an independence of “psychosomatic” from depressive symptoms. In particular, contrary to some evidence derived from other African studies, the present research appears to suggest a possible counterposition of these two ways of expressing depression, commonly considered as autonomous. Accepted: 9 February 1999     

Reliability and clinical usefulness of the short-forms of the Wechsler memory scale (revised) in patients with epilepsy

PURPOSE: The Wechsler Memory Scale-R (WMS-R) is often used for the evaluation of patients with epilepsy, but is time consuming. Two shortened forms of the WMS-R have been published in an effort to reduce the time involved in the test. The purpose of this study is to cross-validate these abbreviated forms in patients with epilepsy. METHODS: We assessed 103 consecutive patients with drug-resistant partial epilepsy being treated in our epilepsy unit. The WMS-R was administered to all patients. The reliability of two shortened versions of the WMS-R were evaluated. The appraisal was performed taking into account the side of the epileptogenic region. The statistical analyses were carried out with the Pearson's correlation and with the intraclass correlation coefficient. RESULTS: Both shortened formulas showed good reliability coefficients for predicting the General Memory and Delayed Recall Indices. In the overall accuracy of the predictions by both short forms no significant differences were found among the three study. groups (right, left or bilateral). However, when considering the predictive error only the three-subtest formulas comprising logical memory, verbal paired associates and visual reproduction efficiently predicted performance, regardless of the side of the epileptogenic region. Of the predicted scores in the overall sample, 92 and 97% fell below the standard error of measurement for general and delayed memory index, respectively. Both short forms correctly classified 89-94% of the performances at the average or impaired level. CONCLUSIONS: The short form of the M-MS-R using three subtests (logical memory, verbal paired associates and visual reproduction) is reliable and time-efficient for estimating the General and Delayed Recall Memory indexes in patients with drug-resistant partial epilepsy.     

The performance of patients with schizophrenia on the wechsler memory scale-revised

The performance of 45 patients with schizophrenia was examined on the Wechsler Memory Scale-Revised (WMS-R). The patients demonstrated a relatively flat performance profile across the five major WMS-R index scores suggesting similar levels of impairment in memory and attentional processes, in memory for visual and verbal materials, and in immediate and delayed recall. The General Memory Index (GMI) was lower than Full Scale IQ (FSIQ) scores in the majority of cases, and a large portion of the sample demonstrated fairly severe differential impairments of memory with FSIQ exceeding the GMI by 15 or more points. These results are consistent with prior findings of memory impairment in schizophrenia and support the validity of the WMS-R as a measure of memory deficits in schizophrenia.     

Confirmatory factor analysis of the wechsler memory scale-revised in a mixed clinical population

Abstract

Previous exploratory factor analyses (EFA) of the Wechsler Memory Scale-Revised (WMS-R) have yielded highly disparate factor structures, while the few reported confirmatory factor analyses (CFA) of this instrument have been more consistent. The present study employed a CFA approach to identify the factor structure of the WMS-R in a mixed clinical sample of 306 patients, the majority of whom had sustained mild, diffuse brain injury. Consistent with previous CFA studies, the present study found that a three-factor solution (attention/concentration, immediate memory, delayed recall) fit the data significantly better than competing models. The validity of separate verbal and visual memory indices was not supported, perhaps because of the heterogeneity of the sample.     

Temporal stability of the WAIS-R and WMS-R in a heterogeneous sample of alcohol dependent clients

Abstract

We examined the temporal stability of WAIS-R IQs, factor scores, Profile Variability Indexes (PVIs), and WMS-R Index scores in a heterogeneous sample of 50 alcohol dependent clients. The average retest interval was approximately 4–5 months. Stability correlations for all scores were significant and high. These results replicate the well-known stability of WAIS-R IQs and confirm the stability of the PVIs and WAIS-R factor scores. WMS-R Index stability coefficients compared favourably with those reported in the manual for a shorter retest interval. Using the standard error of prediction to set a 95% confidence interval around the predicted true score at initial testing, most scores obtained at retest were found to fall within the predicted range.