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Biomedical subjects

B D Townes

Publications and source records attributed to B D Townes.

At least 37 records · Page 2Linked to original sources
PubMed1989

The cost to the central nervous system of climbing to extremely high altitude.

To assess the possibility that climbing to extremely high altitude may result in hypoxic injury to the brain, we performed neuropsychological and physiologic testing on 35 mountaineers before and 1 to 30 days after ascent to altitudes between 5488 and 8848 m, and on 6 subjects before and after simulation in an altitude chamber of a 40-day ascent to 8848 m. Neuropsychological testing revealed a decline in visual long-term memory after ascent as compared with before; of 14 visual items of information on the Wechsler Memory Scale, fewer were recalled after ascent by both the simulated-ascent group (a mean [+/- SD] of 10.14 +/- 1.68 items before, as compared with 7.00 +/- 3.35 items after; P less than 0.05) and the mountaineers (12.33 +/- 1.96 as compared with 11.36 +/- 1.88; P less than 0.05). Verbal long-term memory was also affected, but only in the simulated-ascent group; of a total of 10 words, an average of 8.14 +/- 1.86 were recalled before simulated ascent, but only 6.83 +/- 1.47 afterward (P less than 0.05). On the aphasia screening test, on which normal persons make an average of less than one error in verbal expression, the mountaineers made twice as many aphasic errors after ascent (1.03 +/- 1.10) as before (0.52 +/- 0.80; P less than 0.05). A higher ventilatory response to hypoxia correlated with a reduction in verbal learning (r = -0.88, P less than 0.05) and with poor long-term verbal memory (r = -0.99, P less than 0.01) after ascent. An increase in the number of aphasic errors on the aphasia screening test also correlated with a higher ventilatory response to hypoxia in both the simulated-ascent group (r = 0.94, P less than 0.01) and a subgroup of 11 mountaineers (r = 0.59, P less than 0.05). We conclude that persons with a more vigorous ventilatory response to hypoxia have more residual neurobehavioral impairment after returning to lower elevations. This finding may be explained by poorer oxygenation of the brain despite greater ventilation, perhaps because of a decrease in cerebral blood flow caused by hypocapnia that more than offsets the increase in arterial oxygen saturation.

Adult↗
PubMed1989

Diagnosis of attention deficit disorder with hyperactivity in Chinese boys.

Parental and teacher ratings of adjustment on the Achenbach Child Behavior Checklist and Teacher Rating Form were obtained on 39 subjects diagnosed as having attention deficit disorder with hyperactivity (ADDH), 31 subjects with ADDH plus learning disability (ADDH-LD), and 29 controls. Subjects were all males between the ages of 9 and 11 years and resided in Changsha, People's Republic of China. Significant group differences were found between the two clinical groups and the control group. Ratings by parents and teachers of the ADDH and ADDH-LD groups indicated more behavior problems and poorer social adjustment than controls. ADDH and ADDH-LD groups were not significantly different from one another except on ratings of school and learning problems.

Attention Deficit Disorder with Hyperactivity↗
PubMed1989

Neurobehavioral outcomes in cardiac operations. A prospective controlled study.

To assess the severity and duration of new organic brain dysfunction after cardiac operations, we used an extensive battery of neuropsychologic tests to evaluate 65 patients undergoing coronary artery bypass grafting and 25 patients undergoing intracardiac operations with cardiopulmonary bypass. Patients were tested the day before the operation, before discharge from the hospital, and approximately 7 months later. Compared to 47 nonsurgical control subjects tested at comparable time intervals, surgical subjects showed generalized impairment of neuropsychologic abilities near the time of discharge from the hospital. At follow-up testing, there was no evidence of residual impairment among the surgically treated patients as a whole. In fact, they showed greater improvement compared to initial test scores than did control subjects. However, performance of 10 patients (11%) declined on half of the neuropsychologic variables between preoperative and follow-up testing. Neurobehavioral outcome was not related to the type of operation (coronary bypass versus intracardiac), to factors of cardiopulmonary bypass (duration, aortic occlusion time, hypotension, arterial carbon dioxide tension, minimum hematocrit value, minimum temperature). The only predictor of negative outcome was advanced age. We conclude that, although neurobehavioral impairment is common during hospitalization after cardiac operations, the prognosis for eventual full recovery is favorable, although less so among the elderly.

Anxiety↗
PubMed1988

Neurobehavioral and psychosocial functioning of women exposed to high altitude in mountaineering.

The effects of chronic hypoxemia upon cognition and behavior were studied in women exposed to high altitude in mountaineering. Neuropsychological tests and psychosocial and physiological questionnaires were given to eight women before, during, and immediately after a Himalayan climb to 20,500 feet. Cognitive functioning remained relatively intact with only two significant decrements, complex abstract reasoning and word-finding ability. Significant changes were found on all psychosocial and physiological questionnaires. Feelings of acceptance of others and anxiety declined significantly. Physical symptoms were greatest during the first five days of ascent. Subjects' self-ratings of mental functioning were significantly better after the expedition than either before or during the climb. Self-assessments were correlated with emotions and physical symptoms, not with actual performances on the test battery. It is suggested that complex cognitive tasks and psychosocial functioning be studied in more detail as these were more influenced by exposure to high altitude in mountaineering.

Adult↗
PubMed1988

Test-retest reliability of the Reitan-Indiana Neuropsychological Test Battery for Children Aged 5 Through 8.

The present study attempted to assess the test-retest reliability of the Reitan-Indiana Neuropsychological Test Battery for Children aged 5 through 8 and to establish the magnitude of practice effects for a normal sample of school aged children. The sample population included 191 kindergarten and 193 second grade students who were administered the entire Reitan-Indiana Battery during the first year of the study and again at one year follow-up. Correlation analyses of random half samples of the population revealed 35 of the 39 test indices measured were stable for at least one of the half samples for the younger (kindergarten-first grade) sample with the same being true for 31 of the 39 variables assessed for the older (second-third grade) sample.

Child↗
PubMed1987

Relationships between IQ and neuropsychological measures in neuropsychiatric populations: within-laboratory and cross-cultural replications using WAIS and WAIS-R.

Several studies have reported positive correlations between measures of intelligence (a quasi-subject variable) and level of performance on neuropsychological tests; few, however, have presented test results by IQ grouping, which could be useful for comparative purposes. The present study examined the relationships of WAIS and WAIS-R Full Scale IQ to performance on a neuropsychological battery consisting of the Halstead-Reitan Battery (HRB), the Wide Range Achievement Test (WRAT), and the Wechsler Memory Scale (WMS). Four mixed neuropsychiatric samples provided cross-cultural and within-laboratory replications, two tested with WAIS and two with WAIS-R. Means and standard deviations for each measure were presented by five IQ levels within each sample. IQ was strongly related to scores on problem-solving tasks, auditory and linguistic measures, memory tasks, academic achievement levels, and tactual imperceptions, while motor functioning and sensory suppressions were less strongly related to IQ. IQ level was related to educational level in all samples. Correlations of years of education with dependent variables in the two WAIS-R samples were strong and replicable for WRAT scores, verbal memory measures, linguistic errors on the Aphasia Screening Test, and finger-tapping speeds but not for other HRB measures. Finally, IQ-HRB relationships were compared to those reported for other populations.

Achievement↗
PubMed1987

The Luria-Nebraska and Halstead-Reitan Neuropsychological Test batteries: a cross-cultural study in English and Arabic.

In the present study, the Luria-Nebraska and the Halstead-Reitan Neuropsychological Test batteries were administered to 112 male and female Arabic and English speaking Egyptians enrolled at the American University in Cairo. The aims of the study were to establish normative data, test the effects of language and order of administration upon performance, and examine practice effects and test-retest reliability of the two batteries. Only minimal differences were found between the Arabic and the English administrations. Results revealed strong test-retest reliability coefficients for the HRB and moderate ones for the LNNB. Practice effects were detected on six LNNB scales as well as on the HRB complex problem solving tests (Category and Tactual Performance Test). No other effects were detected. Thus, the initial performance on one battery did not interfere with nor enhance performance on the other battery.

Adolescent↗
PubMed1987

Age group differences on neuropsychological battery performance in a neuropsychiatric population: an international descriptive study with replications.

The relationship of age to performance on the Halstead-Reitan Neuropsychological Battery was examined in three samples drawn from neuropsychiatric populations: an initial sample of 217 subjects, a within-laboratory replication of 307 subjects, and a cross-national replication sample of 101 subjects. The results showed significant relationships of age to subtests of the Halstead-Reitan Battery involving problem-solving abilities and motor strength, which were replicated across the three samples. Verbal and perceptual subtests were not consistently related to age across samples. For those problem-solving and motor tests showing replicated correlations with age. mean scores are provided for three age groups (16-34, 35-54, and 55 and above), and group differences were tested with analysis of variance. These results help clarify for which measures age group differences are consistent in neuropsychiatric populations. Implications of these results for treatment program planning are discussed

Journal Article↗
PubMed1986

Factor analysis of the Wechsler Memory Scale: is the associate learning subtest an unclear measure?

A factor analysis of the Wechsler Memory Scale (WMS) with 30-minute delayed recall scores (percent retained) for the Logical Memory, Visual Reproduction, and Associate Learning subtests indicated that this variant of the WMS taps different types of learning and memory for new material. With regard to the verbal learning/recall subtests, Logical Memory appears to be related to attention/ concentration ability, while Associate Learning is relatively independent. The results also showed that both the easy and hard items from Associate Learning tap the same ability, providing evidence that this subtest is a measure of rote verbal learning. These results support the clinical utility of the WMS with delayed recalls in neuropsychiatric populations.

Journal Article↗
PubMed1986

Neuropsychological changes in a young, healthy population after controlled hypotensive anesthesia.

We investigated the effect of controlled hypotension during halothane anesthesia on brain functions as measured by neuropsychological tests. Anesthesia in 17 patients included controlled hypotension, whereas in another 27 patients hypotension was not induced during surgery for correction of facial abnormalities. Intraoperative EEG recording showed no significant changes in EEG power during the induction of hypotension. Hypotensive anesthesia was not associated with greater postoperative impairment than normotensive anesthesia. Both groups did show short-term postoperative impairment of memory and learning. For at least the first 24 hrs after administration of a general anesthetic agent such as halothane, there is interference with consolidation of memory. This impairment was not apparent in follow-up examinations 6 months later.

Adult↗
PubMed1986

Hemodilution of polycythemic mountaineers: effects on exercise and mental function.

We studied the effects of acute, isovolemic hemodilution on the exercise ability and mental function of four polycythemic mountain climbers (mean hematocrit 58 +/- 1.25%) during the American Medical Research Expedition to Mt. Everest (AMREE). The subjects were studied at 5400 m (PB = 400 mm Hg). Approximately 15% of their blood volume was removed and replaced with an equal volume of 5% human albumin solution. Final hematocrits were 50.5 +/- 1.5%. Before and after hemodilution, the subjects performed psychological and exercise tests. Maximum work level, oxygen uptake, minute ventilation, and blood oxygen saturation did not change. After hemodilution, heart rate increased slightly at all work levels, and there was a small but significant improvement on the psychological tests. It is concluded that this degree of hemodilution was well tolerated and that a hematocrit of greater than 50% conferred no advantage for exercise and may have impaired cerebral function. Although, in these circumstances, isovolemic hemodilution improved cerebration, we feel that this potentially hazardous maneuver is rarely indicated.

Adult↗
PubMed1985

Neuropsychological status of patients with congenital and rheumatic heart diseases: preoperative and postoperative comparison.

Thirty surgical patients receiving surgery for congenital heart or rheumatic heart disease were compared with a match control group on a battery of neuropsychological tests. Subjects were examined prior to surgery, 4 weeks post- and again 6 months postsurgery. Preoperative surgical subjects showed a generalized impairment in functioning suggestive of brain dysfunction secondary to hypoxia. Improvement following surgery was attributed to practice effects.

Adult↗
PubMed1984

Fingertip number-writing errors by psychiatric patients.

Records from 495 psychiatric patients from two neuropsychology laboratories indicated the Fingertip Number Writing test shows a significant and reliable left-hand advantage within and between laboratories. While the left-hand advantage may reflect a right-hemisphere superiority for tactile-spatial processing, it is not possible to distinguish between right hemispheric functional superiority and practice effects between hands because the standard fingertip writing task always starts with the right hand.

Dominance, Cerebral↗
PubMed1984

Asymmetric cognitive function in anorexia nervosa.

Three anorexics, one at normal weight, were examined, with a neuropsychological battery including the Halstead-Reitan tests. Their data were contrasted with that of 24 psychiatric controls matched for age, sex and IQ. Individually and as a group the anorexics showed above average verbal/academic scores and impaired spatial skills, whereas visual-motor and problem solving skills were equivalent to controls. Somatosensory recognition was impaired bilaterally in all three patients, and motor skills were low in the two emaciated patients. Other sensory tests and intermanual comparisons of sensory and motor skills were not impaired relative to controls. The findings suggest that a spatial reasoning deficit may be a predisposing or maintaining factor in this disorder. High verbal skills, in contrast, may reflect substantial left hemisphere contributions to the anorexic's cognitive style.

Adult↗