The Memory Assessment Scales and lateralized temporal lobe epilepsy

We report Memory Assessment Scales (MAS) performance in 101 patients with unilateral temporal lobe epilepsy (TLE; left, n = 51; right, n = 50) with left cerebral language dominance. A significant multivariate group effect was present for the major summary indices (Verbal Memory, Visual Memory, and Global Memory, p < .04). Univariate analyses revealed no significant differences for either the Global Memory or Verbal Memory summary scores, although a significant group difference was present for Visual Memory (p < .04). The Verbal Memory-Visual Memory discrepancy score was significantly different between right and left TLE groups (p < .004). Verbal Memory scores were at least 14 points lower than Visual Memory scores in 34 patients (left = 20, 59%; right = 14, 41%). Visual Memory scores were at least 14 points lower than Verbal Memory performance in 20 patients (left = 5, 25%; right = 15, 75%). Diagnostic efficiency statistics show higher sensitivity but lower specificity in group classification for left TLE patients. These data suggest that the MAS is sensitive to material-specific memory deficits associated with a unilateral temporal lobe seizure focus. However, over one-third of the patients (19/54) with at least a 14-point Verbal Memory-Visual Memory discrepancy were classified incorrectly. The MAS, like other material-specific memory measures, should be interpreted within the context of other clinical findings.     

The effect of early versus late onset of temporal lobe epilepsy on hemispheric memory laterality: an intracarotid amobarbital procedure study.

Thirty-three temporal lobe epilepsy (TLE) patients, 19 left TLE and 14 right TLE, underwent an intracarotid amobarbital procedure. For each patient, hemispheric memory laterality was determined by measuring the relative magnitude of recognition memory following left versus right hemisphere injection of sodium amobarbital. The patients were divided into early and late seizure onset groups, based on the median age (13 yrs) of seizure onset of the total sample. Early-onset left TLE was associated with a greater tendency toward right hemispheric representation of both verbal and visual memory compared with late-onset left TLE. Early-onset right TLE was associated with a greater tendency toward left hemispheric representation of visual, but not verbal, memory compared with late-onset right TLE. These findings indicate that interhemispheric plasticity for memory is greater in early than in late life, bidirectional, and at least partially material-specific.     

Diagnostic efficiency and material specificity of the Warrington Recognition Memory Test: a collaborative multisite investigation.

Two studies examined the Warrington Recognition Memory Test (RMT) discrepancy index (Words-Faces) in a large sample of patients heterogeneous with respect to age, education, gender, and neurological diagnosis. In Study 1 (N = 504) we used cutoffs from the Words-Faces discrepancy scores derived from Warrington's original validation sample to attempt to accurately classify patients with left, right, or diffuse brain damage. Sensitivity for left hemisphere patients (Faces > Words) was 10% with a specificity of 88%, whereas sensitivity for right hemisphere patients (Words > Faces) was 48% with a specificity of 86%. For patients with diffuse brain damage (Words = Faces) sensitivity was 69% and specificity was 38%. In Study 2 (N = 263), we examined the relationship between the Words-Faces discrepancy score and Wechsler Memory Scale-Revised (WMS-R; Wechsler, 1981) Logical Memory and Visual Reproduction subtests. Contrary to predictions, patients with Words > Faces performed better on both WMS-R subtests; the Faces > Words discrepancy was not related to Visual Reproduction performance. Potential reasons for these negative findings are discussed, as well as cautions for future RMT discrepancy index use.     

Assessing nonverbal memory with the Biber Figure Learning Test-Extended in temporal lobe epilepsy patients.

Material-specific memory dysfunction was assessed using a nonverbal, visuospatial, supraspan learning test, the Biber Figure Learning Test-Extended (BFLT-E), in 71 left-hemisphere language-dominant epilepsy patients prior to anterior temporal lobectomy (ATL) and in 48 age-matched healthy subjects. Two matched forms of the BFLT-E yielded comparable scores, indicating that this task may be used to track memory performance over time in individual patients. Right temporal lobe epilepsy (RTLE) and left temporal lobe epilepsy (LTLE) patients performed below healthy subjects on all free-recall measures. RTLE, but not LTLE, patients also differed from healthy subjects in recognition memory discrimination. Furthermore, the RTLE patients performed below LTLE patients on measures specific to long-term memory abilities. The BFLT-E appears to be a useful clinical tool for assessing different components of visuospatial memory in patients with lateralized mesial temporal lobe (MTL) dysfunction. The test is sensitive to visuoconstructional problems associated with various types of brain damage, but it also distinguishes material-specific, nonverbal, visuospatial memory impairments in patients with neurological dysfunction in the non language-dominant right temporal lobe.     

The impact of constructional impairment on the WMS-R visual reproduction subtests

The present study investigated the impact of constructional impairment on performance on the WMS-R Visual Reproduction subtests that measure memory for visual material. Thirteen subjects with constructional impairment had lower scores on the immediate and half-hour delayed Visual Reproduction subtests, relative to a cognitively comparable group of subjects without constructional impairment. However, the two groups did not differ with respect to their performance on the WMS-R Logical Memory subtests, which measure verbal memory. The implications of these modality specific findings among subjects with constructional impairment are discussed, and recommendations for clinicians who utilize the WMS-R are provided.     

Traditional and computerized assessment procedures applied to the evaluation of memory change after temporal lobectomy.

After establishing that 40 temporal lobectomy patients (20 right, 20 left) demonstrated the same pattern of memory compromise as has been reported in prior studies, we examined the sensitivity of computerized tests of everyday memory skills to the cognitive change associated with temporal resection. Multiple cognitive deficits occur after left, but not after right, temporal lobectomies. Memory impairment after surgery is not limited to traditionally structured memory tests but is also evident on tasks designed to simulate activities of daily life.     

Wechsler Memory Scale-Revised in closed head injury

This study was undertaken to determine the ability of the Wechsler Memory Scale-Revised (WMS-R) to differentiate a group of closed head injury patients from a group of controls and determine how injury severity and attentional deficits are associated with WMS-R performance. The relationship of WMS-R performance to everyday memory also was assessed. The head injured group performed more poorly than controls on all five WMS-R indices and exhibited greater impairments on tasks that measure retention. In the original sample only the Visual Memory Index correlated with injury severity; in a larger sample, all four memory indices correlated modestly with injury severity. Patients who performed more poorly on the WMS-R also received poorer ratings on an independent assessment of everyday memory.     

Delayed recall on the Wechsler memory scale-revised: The factor structure revisited

Although delayed recall tasks are prominent features of the popular Wechsler Memory Scale-Revised (WMS-R), exploratory factor analyses consistently have failed to identify an associated delayed recall factor. The present study tested the hypothesis (Elwood, 1991b) that a delayed recall factor could be found by substituting percent retained (saving) scores for the existing WMS-R delayed recall subtest scores. Principal component analyses of age-corrected WMS-R immediate and save scores in a mixed clinical sample failed to find the hypothesized save factor. Both the scree and MAP tests retained one general memory factor, which accounted for 42.2% of the total variance. Independent statistical programs produced essentially equivalent results. Clinical implications of these findings are discussed.     

Neuropsychological sequelae of hard metal disease.

To evaluate the memory complaints of a group of patients with hard metal disease, 12 adult, former tungsten carbide workers with hard metal disease and 26 healthy, unexposed control subjects matched for age, race, sex, occupational status and education were administered the Wechsler Memory Scale-Revised (WMS-R), the Peterson Word Triad Test, Squire's Current Events Test (including both the recall and recognition forms), and Squire's Television Title Recognition Test. The exposed group demonstrated deficits in short-term verbal memory, allocation of central processing resources, and remote verbal memory compared to the control group. Visual memory was spared. Comparisons were made to previous investigations of memory functioning within the toxicology literature.     

Confirmatory factor analysis of the Wechsler Memory Scale-Revised standardization sample.

A maximum likelihood confirmatory factor analysis was preformed by applying LISREL to the variance-covariance matrix obtained from standardization of the Wechsler Memory Scale-Revised (WMS-R) (N = 316). Analyses were designed to determine which of seven hypothesized factor solutions could best explain memory function as measured by the WMS-R. Competing latent variable models were identified in previous exploratory and confirmatory factor analytic studies. The measurement error matrix was set to remove method variance shared by the immediate and delayed trials of the same subtest. Hypothesized factors were fixed and allowed to correlate. Results indicated that a three-factor model, including Attention/Concentration, Immediate and Delayed Memory, explained 91% of the score variance and produced a significantly better fit than the Attention/Concentration--General Memory or Attention Concentration--Visual/Verbal Memory solutions. Findings support previous work suggesting that the WMS-R measures separate memory functions, and that the verbal/nonverbal Index distinction may not be a viable one.     

The role of the frontal lobes in memory: evidence from unilateral frontal resections for relief of intractable epilepsy.

The current investigation explored processes associated with memory deficits in patients with frontal lobe dysfunction. Specifically, we examined deficits associated with the encoding, consolidation, and retrieval of information in memory in 53 patients who underwent either a unilateral frontal (N=13) or temporal (N=40) lobe resection for relief of intractable epilepsy. Post-surgical memory scores indicated that the frontal group and the temporal group did not differ in consolidation of information, as defined by the information forgotten between immediate and delayed recall. Instead, the temporal group evidenced significantly poorer recall of verbal information at both immediate and delayed recall. This effect was especially strong in the left temporal group for the recall of verbal information. Although no group differences were observed in the degree to which patients semantically organized information or made recency discriminations, the frontal group exhibited significantly weaker release from proactive interference than the temporal group, suggesting some impairment in encoding and retrieval processes associated with frontal lobe dysfunction.     

The East Boston Memory Test: A clinical screening measure for memory impairment in the elderly

Comparisons between the East Boston Memory Test (EBMT), a brief verbal memory measure used in epidemiological studies with dementia, selected Wechsler Memory Scale-Revised (WMS-R) subtests, and the Mini-Mental State Examination (MMSE) were investigated with 23 geriatric patients diagnosed with dementia. Significant correlations between the EMBT and WMS-R verbal subtests were predicted and occurred (r = .42 to .64). A five minute EBMT recall correlated most highly with the WMS-R Logical Memory subtests. The sensitivity of the EBMT in detecting cognitive impairment was investigated and compared with the sensitivity of the MMSE. The EBMT correctly classified 78% of subjects, compared to a 70% correct classification rate with the MMSE. Implications of these findings and suggestions for future research directions are discussed. © 1996 John Wiley & Sons, Inc.     

Material-specific memory in temporal lobe epilepsy: effects of seizure laterality and language dominance

This study investigated the effects of seizure laterality and language dominance on material-specific memory in temporal lobe epilepsy (TLE). Left TLE (LTLE) patients with left-hemisphere language dominance (LHLD) showed significantly higher nonverbal than verbal memory capacity, whereas right TLE patients with LHLD showed significantly better verbal than nonverbal memory capacity. LTLE patients with non-left-hemisphere language dominance (NLHLD) showed significantly better verbal memory capacity compared with LTLE patients with LHLD. Thus, selective verbal or nonverbal memory deficits that are dependent on side of seizure onset were apparent in patients with LHLD but not in patients with NLHLD. Relative sparing of verbal memory capacity in LTLE patients with NLHLD may reflect interhemispheric reorganization of verbal memory function.     

Brain atrophy associated with baseline and longitudinal measures of cognition

The overall goal was to identify patterns of brain atrophy associated with cognitive impairment and future cognitive decline in non-demented elders. Seventy-one participants were studied with structural MRI and neuropsychological testing at baseline and 1-year follow-up. Deformation-based morphometry was used to examine the relationship between regional baseline brain tissue volume with baseline and longitudinal measures of delayed verbal memory, semantic memory, and executive function. Smaller right hippocampal and entorhinal cortex (ERC) volumes at baseline were associated with worse delayed verbal memory performance at baseline while smaller left ERC volume was associated with greater longitudinal decline. Smaller left superior temporal cortex at baseline was associated with worse semantic memory at baseline, while smaller left temporal white and gray matter volumes were associated with greater semantic memory decline. Increased CSF and smaller frontal lobe volumes were associated with impaired executive function at baseline and greater longitudinal executive decline. These findings suggest that baseline volumes of prefrontal and temporal regions may underlie continuing cognitive decline due to aging, pathology, or both in non-demented elderly individuals.     

Wechsler Memory Scale: a selective review of the literature.

Research on the Wechsler Memory Scale (WMS) is reviewed with respect to questions of its reliability, factor structure, construct validity, and utility. The relationship of Memory Quotient to Full Scale IQ is explored and the conditions under which disparity between the two scores may be clinically useful indicated. Despite its numerous limitations, the WMS has been a sensitive test of short-term verbal memory. As such, it may be helpful in identifying impairment of the dominant (left) temporal lobe and its medial hippocampal connections. The test is badly in need of re-standardization, however, and suggestions for improving the instrument are made.     

Material-specific memory in traumatic brain injury: differential effects during acquisition, recall, and retention

Material-specific memory refers to the ability to learn and recall new episodic information on the basis of the nature of the stimulus material (e.g., verbal vs. nonverbal-visuospatial). Structural equation modeling was used to analyze data from a sample of patients with traumatic brain injury to compare 3 models of memory functioning: material-specific, material-specific plus general, and general (non-material-specific). The models were examined separately for acquisition, delayed free recall, and retention aspects of memory. Results suggest that, at least in a population with traumatic brain injury, the acquisition of new information takes place in a material-specific memory fashion, delayed free recall involves both material-specific and general (non-material-specific) memory components, but retention relies primarily on general (non-material-specific) memory processes.     

Neuropsychological deficit profiles in senile dementia of the Alzheimer's type.

Recent studies using Wide Range Achievement Test-Revised (WRAT-R) Reading scores as estimates of premorbid abilities have demonstrated that distinct neuropsychological deficit profiles may be associated with specific cognitive disorders such as traumatic brain injury [Brain Inj. 9 (1995) 377] and lupus [Appl. Neuropsychol. 7 (2000) 96], and that these deficit scores predict both functional and financial outcomes [J. Head Trauma Rehab. 14 (1999) 220]. Although the main cognitive deficits associated with senile dementia of the Alzheimer's type (SDAT) are well known, the relative degree of impairment in each has yet to be adequately determined. The present study calculated indices of relative decline (zDiff) for 32 patients with probable SDAT by comparing estimates of premorbid functioning to concurrent neuropsychological test scores. The results suggest that intelligence is least declined in SDAT [Wechsler Adult Intelligence Scale-Revised (WAIS-R) FIQ, zDiff=-0.72], followed by attention [Wechsler Memory Scale-Revised (WMS-R) Attention Index, zDiff=-1.14], memory (WMS-R General Memory, zDiff=-2.12; WMS-R Delay Memory, zDiff=-2.33), speed of processing (Trails A, zDiff=-2.85), and cognitive flexibility (Trails B, zDiff=-5.33). Clinical and research implications are discussed.     

Russells revised wechsler memory scale in the evaluation of dementia

Matched 31 elderly normals and 25 patients with suspected Alzheimer's disease for age and education and administered the Revised Wechsler Memory Scale (WMS-R). The patient group performed significantly less well than the control group on all WMS-R subtests. A bimodal distribution of Percent Retained scores was noted in the patient group, but not in the control group. Results are discussed with respect to the clinical utility of the WMS-R as a memory screening procedure.     

Normal aging and forgetting rates on the Wechsler Memory Scale-Revised.

The deleterious effects of aging on various cognitive abilities are widely recognized, yet little is known regarding what constitutes "normal" memory test performance in individuals over the age of 74. In this study, forgetting rates for verbal and nonverbal material from the Wechsler Memory Scale-Revised (WMS-R) were examined in groups of older healthy individuals, age 50-70 and 75-95. Despite equivalent scores on measures of global cognitive status and attention/ concentration, the older group demonstrated significantly more rapid forgetting rates on the Visual Reproduction, Verbal Paired Associates, and Visual Paired Associates subtests of the WMS-R. Although patients with Alzheimer's disease also evidence very rapid forgetting on some subtests, the severity and pattern of losses appears useful in differentiating "abnormal" forgetting from that exhibited by normal elderly subjects. Preliminary normative data for normal elderly subjects on the WMS-R are presented, and the need for appropriate norms for elderly individuals is discussed.     

Clinical Utility of Wechsler Memory Scale-Revised and Predicted IQ Discrepancies in Closed Head Injury

Comparisons between Wechsler Memory Scale-Revised (WMS-R) indexes and Wechsler Adult Intelligence Scale-Revised (WAIS-R) IQ scores have been proposed to identify severity of memory deficits. However, many neurologic conditions reduce both intellectual and memory functioning, and thus, examining differences between these scores may be of little value. Closed head injured subjects who completed the WMS-R were divided into either mild injury (MI, n = 41) or moderate/severe (SI, n = 41) injury groups based on trauma severity indicators and were matched on age and level of education. The Oklahoma Premorbid Intelligence Estimation (OPIE), a regression formula that takes into account demographic variables as well as IQ performance, was calculated for each subject. Discrepancy scores were calculated between predicted IQ scores and WAIS-R IQ and WMS-R indexes. SI head-injured subjects displayed significantly larger discrepancies (19 points) between OPIE scores and Delayed Recall Indexes from the WMS-R than the MI subjects (10 points). Significantly larger percentages of subjects in the SI group displayed significant (>SD) reductions in many of the WMS-R and WAIS-R scores from estimates than subjects in the MI group. Comparing current memory functioning to estimates of premorbid intellectual ability appears to be a sensitive indicator of presence and degree of intellectual and memory dysfunction in head trauma patients. Results also provide evidence that estimates of premorbid intellectual ability can serve as estimates of premorbid memory functioning.