Adrenalectomy-induced memory deficits: role of plasma glucose levels

Circulating glucose levels regulate memory storage under several conditions. This study examined the contribution of blood glucose levels to the transient memory impairment seen in adrenalectomized rats. Inhibitory (passive) avoidance retention performance, blood glucose levels, and glycemic responses to footshock were tested 1, 2, and 8 days after adrenalectomy. Adrenalectomized animals demonstrated a transient inhibitory avoidance deficit 1 and 2 days after surgery which recovered by 8 days. The adrenalectomy-induced memory deficit was accompanied by decreased resting blood glucose levels. In animals tested 2 days after adrenalectomy, this decrease in baseline blood glucose levels was exacerbated by further reductions, rather than the normal increases, in circulating glucose levels after training. The magnitude of blood glucose increases after glucose injection was decreased in adrenalectomized animals tested 2 days after surgery. Posttraining glucose injections restored the retention performance of animals trained 2 days after adrenalectomy to that of sham-operated animals. These findings suggest that abnormalities in blood glucose regulation may contribute, in part, to the transient memory impairment seen after adrenalectomy. Additionally, the results further implicate blood glucose in the regulation of CNS information processing systems.     

Tests of memory in narcoleptics

This study attempted to evaluate the validity of self-reports of memory deficits in narcoleptics by comparing the scores of these patients with the scores of matched control subjects on standardized tests of memory function. After completing a short interview designed to elicit qualitative information about memory difficulties, 30 narcoleptic subjects and 30 control subjects completed the Wechsler Memory Scale (WMS), Rey-Auditory Verbal Learning Test, the Rey Complex Figure Test, Strub and Black's List of Letters, and the Symbol Digits Modalities Test (SDMT). In addition, the Profile of Mood States (POMS) was used to detect variation in performance due to anxiety or fatigue. Continuous polygraphic recordings were obtained during the testing to detect any changes in alertness. Subjects with narcolepsy experienced more difficulty in maintaining attention than control subjects, as evidenced by significantly more perseveration errors (p less than or equal to 0.01) on Strub and Black's List of Letters. Despite differences in their ability to sustain attention, there were no significant differences between narcoleptic and control subjects on measures of concentration (Digit Span from the WMS, and the SDMT). Furthermore, there was no objective evidence of memory impairment when the scores of narcoleptic and control subjects were compared on standardized tests of immediate and delayed recall, as well as on tests of verbal and visual memory.     

Memory assessment using the Strub-Black Mental Status Examination and the Wechsler Memory Scale

A systematic mental status exam often can differentiate accurately patients with organic brain disease from normal persons and those with functional disorders. The present study attempts to validate the memory portion of the Strub-Black Mental Status Exam by comparing it to the Wechsler Memory Scale. Twenty-five brain-damaged and 25 routine medical patients were given Form I of the Wechsler Memory Scale and the memory portion of the Strub-Black Mental Status Exam at their hospital bedside. Results indicate significant differences in almost all scores between the brain-damaged and normal groups on both the Wechsler Memory Scale and Mental Status exam; the Mental Status Exam differentiated between groups at a higher level of significance of ANOVA and ANCOVA comparisons of total memory scores, as well as several subtests. In these samples, age, more than education, was an important factor that affected memory test performance. The Mental Status Examination appears valid for the differentiation of clinical samples and for the documentation of specific aspects of memory dysfunction in individual brain-damaged patients. This study represents a beginning step in providing normative data on components of the Strub-Black mental status examination.     

Lateralized anterior and posterior lesions and performance on Digit Span and Russell's revision of the Wechsler Memory Scale

Performance on the Russell (1975) revision of the Wechsler Memory Scale and the Digit Span subtest of the Wechsler Adult Intelligence Scale by subjects with lateralized anterior and posterior lesions was investigated. Ss were right-handed men whose brain lesions were identified on the basis of neurodiagnostic tests as being lateralized to either the left or right hemisphere and restricted to either the anterior or posterior side of the central sulcus. A normal comparison group was formed of Ss suspected of having neurological damage and referred for neuropsychological testing but who had normal neurodiagnostic examinations. It was predicted that both the laterality and caudality of lesions would affect memory task performance. This prediction was fully supported for the logical memory task and partially supported for the figural memory and digit span tasks.     

Cognitive and behavioral findings in children taking theophylline

In a prior pilot study involving six children, we noted improved memory and concentration and improved behavior when these children were switched from theophylline to cromolyn sodium therapy. We now report the findings in 29 children (24 boys and five girls), aged 7 to 12 years. In this study, a double-blind, double-dummy randomized design was used so that half the subjects continued to receive theophylline and the other half was actually switched from theophylline to cromolyn sodium therapy. Assessment again consisted of the revised Wechsler Intelligence Scale for Children, the Selective Reminding test, the Benton Visual Retention test, Stroop tests I and II, and the Child Behavior Checklist. The group receiving placebo theophylline/active cromolyn sodium therapy demonstrated greater improvement on all tests of memory and concentration, with greatest significance for the Stroop test (p less than 0.03 by analysis of covariance). There were also significant correlations between length of time theophylline was taken and scores on the depression (p less than 0.03) and the obsessive-compulsive (p less than 0.04) subscales of the Child Behavior Checklist. These results support the findings of the previous pilot study but, in addition, raise concern about depression and anxiety as possible long-term side effects of long-term theophylline therapy.     

Memory impairment in patients with cirrhosis

BACKGROUND AND AIM: Subclinical hepatic encephalopathy (HE) in cirrhotic patients is usually characterized by memory impairment and psychomotor slowing. Our aim was to investigate memory status in cirrhotic patients with and without clinically overt HE. MATERIAL AND METHODS: Thirty-two cirrhotic patients (10 female and 22 male) aged 49 +/- 17 years and 20 healthy subjects (six female and 14 male) aged 46 +/- 12 years were included in the study. Memory status was defined by Wechsler Memory Scale, verbal memory process and complex memory process tests. RESULTS: Grade-1 HE was detected in 7 (22%) patients with cirrhosis. We detected 36 to 92% decrement in various memory tests in cirrhotic patients without HE as compared to healthy subjects. The scores for all psychometric testing results were significantly lower in cirrhotic patients without HE as compared to healthy subjects. We detected 42.9 to 100% decrement in various memory tests in cirrhotic patients with HE than cirrhotic patients without HE. However, there was no statistical significant difference between cirrhotic patients with and without HE. There was no statistical significant difference in cirrhotic patients with Child-Pugh A, B, and C. CONCLUSION: In conclusion, memory status was influenced in which patients with cirrhosis yet has a normal mental and neurological status to routine clinical examination (subclinical HE). Occasionally, decreased memory performance may adversely affect the satisfaction and lifestyle of these patients. Therefore, subclinical HE is an important social problem.     

The psychometric structure of the Wechsler Memory Scale in comparison to the WAIS-R in a low-IQ clinical population

The psychometric structure of the Wechsler Memory Scale (WMS) and its relationship to the revised Wechsler Adult Intelligence Scale (WAIS-R) were studied in an outpatient population of 103 individuals with low Full Scale IQ scores (M = 71). We found that the age correction of the WMS scores gave memory quotients (WMQ) equivalent to WAIS-R FSIQ scores, but our findings also raised problems of interpretation. If the usual rule of thumb of a 12-point discrepancy between the MQ and the FSIQ were applied, the WMS might be relatively insensitive to memory impairment in this low-IQ clinical population, in which more numerous cases of impairment could be expected. Principal components analysis of the WMS raw scores and three WAIS-R scores included as reference variables yielded five orthogonal factors: Attention/Concentration; Visual Reproductions; New Verbal Learning; Well-learned Semantic Knowledge; and Intelligence. We argue that raw scores on the WMS should be reported to optimize possible diagnostic specificity and to align the WMS with experimental and clinical research in various types of memory functioning and impairment.     

Glucoregulatory and order effects on verbal episodic memory in healthy adolescents after oral glucose administration

The ingestion of oral glucose has been observed to facilitate memory performance in both elderly individuals and in young adults. However, fewer studies have investigated the effect of glucose on memory in children or adolescents. In the present study, the ingestion of a glucose laden drink was observed to enhance verbal episodic memory performance in healthy adolescents under conditions of divided attention, relative to a placebo drink. Further analyses found that this glucose memory facilitation effect was observed only in adolescents exhibiting better glucoregulatory efficiency. These findings demonstrate that the glucose memory facilitation effect can be generalised to younger individuals. The importance of controlling for treatment order in within-subjects designs investigating the glucose memory enhancement effect is also discussed.     

Glucose enhancement of memory in elderly humans: an inverted-U dose-response curve.

In animals, enhancement of memory with glucose and many other treatments is characterized by an inverted-U dose-response curve. The present experiment examined the dose-response curve for glucose enhancement of memory in elderly humans. Using a repeated measures, counterbalanced, crossover design, the subjects (60-82 year olds) were tested on four sessions, separated by 1 week or more, for performance on the Wechsler Logical Memory Test after ingestion of a fruit drink sweetened with glucose (0, 10, 25, and 50 g) and saccharin matched to comparable taste. The findings indicate that glucose enhanced performance on this test in an inverted-U dose-response manner, with optimal enhancement obtained at the 25 g glucose dose. These findings provide further demonstration of glucose enhancement of memory in elderly humans and also describe an additional analogy between the characteristics of glucose enhancement of memory in animals and humans.     

Is age kinder to the initially more able? A study of eminent scientists and academics.

Elderly eminent academics and blue-collar workers were compared with Doctor of Philosophy students and trade apprentices to investigate whether intelligence and memory deteriorate at a slower rate in persons with high ability. The elderly groups showed decline on tests of perceptual-motor speed, visuospatial reasoning, inferential thinking and memory relative to the young subjects. Initial ability determined the level of intellectual performance, such that elderly academics maintained their initial advantage over the elderly blue-collar workers. However, with the exception of the Similarities subtest of the Wechsler Adult Intelligence Scale, the rate of change on tests of memory and intelligence did not differ for the high- and low-ability groups. The hypothesis that high ability is associated with a slower rate of cognitive decline was not supported.     

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.     

Learning and memory function in men with untreated blood pressure elevation

Learning and memory processes were compared in 20 men with untreated blood pressure elevation and 20 normotensive control subjects matched for age, education, and average alcohol consumption. Subjects were identified from a larger sample of 469 factory workers who had participated in an epidemiologic investigation. Three measures (e.g., Symbol-Digit Learning Test [Ryan & Butters, 1980] and Visual Reproductions-Immediate and Delayed Recall [Wechsler, 1945] ) from a previously administered test battery were chosen for comparison on the basis of statistical power calculations. Results indicate that relative to normotensive control subjects, men with elevated blood pressure performed more poorly on all three tests. These results are independent of other known influences on neuropsychological performance and are likely a consequence of elevated blood pressure.     

Cognitive profile in adult, normal intelligent female fragile X carriers.

Here we present the results of the study of the cognitive profile of 11 adult, normally intelligent female fragile X [fra(X)] carriers. In all individuals 3 types of testing were performed: full scale Wechsler Adult Intelligence Scale, a set of neuropsychological tests and an arithmetic achievement test. All 11 subjects showed an average to above-average intelligence but 10 of 11 performed better on the performance than on the verbal subscale. Neuropsychological tests suggest a dysfunction of the reticulo-thalamic axis with deficiency on tests requiring visual memory and a pronounced deficiency of attention skills combined with an impulsive way of completing tests.     

A comparison of the WISC-R and the WAIS-R with special education students

The results from Wechsler Adult Intelligence Scale-R (WAIS-R) and Wechsler Intelligence Scale for Children-R (WISC-R) with a sample of exceptional adolescents (N = 28) were compared over a 3-year period to determine whether the subjects can be expected to obtain similar subtest scores and similar VIQ, PIQ, and FSIQ scores. Results indicated that the sample scored higher on the WAIS-R Verbal and WAIS-R Full Scale than on the WISC-R Verbal and Full Scale. The findings are discussed in terms of the clinical application, especially as they relate to retesting exceptional children and youth with the WAIS-R.     

Breakfast, blood glucose and memory.

The hypothesis that blood glucose levels influence memory was re-examined. The performance on two memory tests was quicker when breakfast had been taken, suggesting that the ability to retrieve memories had been facilitated. Performance on a spatial memory test correlated significantly with blood glucose levels.     

Attentional Deficit Disorder and short-term visual memory

Twenty-four children with Attentional Deficit Disorder (ADD) were compared to a control group of 17 children with emotional problems. All the subjects were tested on the Wechsler Intelligence Scale for Children-Revised (WISC-R), along with an adaptation of the Coding subtest to measure short-term visual memory. The results showed superiority of the control group on the short-term visual memory task. The correlations of short-term visual memory with each of the subtests of the WISC-R were different for each group. For the emotional group short-term visual memory correlated significantly with the WISC-R verbal scores, while in the ADD group visual memory more often significantly correlated with performance subtests. In the discussion an attempt was made to explore the reasons for these differences and their implications for academic tasks.     

Cognitive demand and blood glucose

Previous research has identified that glucose administration can enhance cognitive performance, especially during more intense cognitive processing. There appears to be a reciprocal relationship between falling glucose levels and cognitive performance, particularly under conditions of cognitive demand. The present placebo-controlled, double-blind, balanced, crossover study examined the possibility that a high cognitive load may produce changes in blood glucose levels. A secondary aim was to examine the effects of glucose on tasks of varying cognitive demand load. The effects of a glucose drink on participants' performance of a serial subtraction task (computerised Serial Sevens), a somatically matched control task (key-pressing), a short interval Word Memory task and a Word Retrieval (Verbal Fluency) task were assessed. The change in blood glucose during the demanding computerised Serial Sevens was compared to the change occurring during the key-pressing control. Glucose consumption significantly improved performance on Serial Sevens, with a trend for improved performance on Word Retrieval and no effect on the Word Memory task. Compared with the control task, Serial Sevens resulted in a significant reduction in blood glucose in both drink conditions. This accelerated decay was significantly greater following glucose than placebo. It is suggested that the amount of cognitive load associated with task performance is an index of its sensitivity to enhancement by glucose. Furthermore, a period of intense cognitive processing leads to a measurable decrease in levels of peripherally measured blood glucose, which may be linked to increased neural energy expenditure. However, the relative contribution of central and peripheral (e.g. cardiac) activity to this effect has yet to be determined.     

Comparison of the PPVT-R and WAIS-R in state hospital psychiatric patients

This study examined the relationship between the Peabody Picture Vocabulary Test-Revised (PPVT-R) and Wechsler Adult Intelligence Scale-Revised (WAIS-R) in 40 adult psychiatric inpatients. The tests were administered to the patients in counterbalanced order as part of their overall psychological evaluation. Mean scaled scores were obtained for both tests. There were no significant differences between PPVT-R scores and WAIS-R Verbal, Performance, and Full Scale IQ scores. Significant correlations between the PPVT-R and all three WAIS-R scores also were obtained. However, further analysis indicated a great deal of variability between individual PPVT-R and WAIS-R Full Scale scores. In addition, the PPVT-R was found to underestimate significantly the WAIS-R IQ scores of a subgroup (N = 13) of mildly mentally retarded subjects. A tendency for the PPVT-R to overestimate the WAIS-R as IQ improved also was noted.     

Blood glucose changes and memory: effects of manipulating emotionality and mental effort

Increasing the emotionality of target material often facilitates memory performance which may be linked to the liberation of glucose. Conversely, increasing mental effort leads to reduced performance and measurable falls in blood glucose. A 2 x 2, parallel groups experiment examined these two phenomena directly by assessing blood glucose levels and memory for neutral and emotional word lists, both with and without a secondary task. Co-performing the secondary task significantly reduced blood glucose in the neutral word condition only and resulted in a global reduction of memory performance in both neutral and emotional word conditions. Processing emotional material resulted in significantly raised blood glucose levels, however, there was no advantage for memory of emotional words. A follow-up study confirmed that the emotionality manipulation was effective. We conclude that there exists a clear relationship between reduced blood glucose and impaired memory performance during periods of mental effort. However, the relationship between physiological and cognitive processes associated with processing emotional material are more complex.     

Factor structure of the Wechsler memory scale-revised in relation to age and educational level.

The factor structure of the Wechsler Memory Scale-Revised was examined for 3 age groups (or= 56) and three educational levels (< 12, 12. > 12) in a large group of patients (n = 434) referred for examination at two large medical centers. The subtests of the Wechsler Memory Scale Revised were subjected to principal components factor analyses. A separate set of analyses were performed that included the Verbal IQ and Performance IQ scores from the WAIS-R. Consistent with previous reports of age related changes in spatial function there appeared to be somewhat greater loading of nonverbal memory tests on verbal factors with increasing age. Inclusion of IQ scores appeared to have an affect on the content and relative prominence of the various factors in those subgroups formed on the basis of educational level. The results are discussed in regard to clinical use of the WMS-R and directions for future research.