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Biomedical subjects

W G Snow

Publications and source records attributed to W G Snow.

34 records · Page 2Linked to original sources
PubMed1989

Psychological, topographic EEG, and CT scan correlates of frontal lobe function in schizophrenia.

This study examined frontal lobe function in a group of 20 patients with schizophrenia, on and off medication, compared to 20 normals matched for age, sex, handedness, intelligence, and educational level. Schizophrenic patients generally did not perform as well as normals on the Wisconsin Card Sorting Test (WCST). Patients off medication performed less well on this test than those on medication. Those on medication did not perform as well as those off medication on the design and word fluency tests, which suggested that medications may affect various aspects of frontal lobe function differently. During the WCST, normal subjects demonstrated an increase in beta mean frequency of the electroencephalogram in frontal and centrotemporal regions which was not statistically significant in either schizophrenic group. This shift in beta mean frequency was found to correlate positively with performance on the WCST in normals, but not in patients. Patients with more negative symptoms tended to show a smaller increase in beta mean frequency during the WCST. Performance on the WCST was correlated negatively with ventricle-brain ratio in all subjects, suggesting that frontal lobe function might be related to computed tomographic measures in the normal population as well as in schizophrenic patients. There was no correlation with performance on the WCST and length of illness.

Adult↗
PubMed1989

WAIS-R test-retest reliability in a normal elderly sample.

We examined the 1-year test-retest reliability of WAIS-R Verbal, Performance, and Full-Scale IQs in a sample of 101 older normal individuals (mean age = 67.1). The respective Pearson rs were .86, .85, and .90. The median retest reliability coefficient for the WAIS-R subtests was .71. The test-retest reliability for the Verbal-Performance Discrepancy was .69. These data indicate that IQ scores are reliable in older normal individuals for this retest interval, but less confidence can be placed in the reliability of subtest scores and the Verbal-Performance Discrepancy.

Aged↗
PubMed1989

Dementia diagnosis.

Explore the source record for details and available documents.

Alzheimer Disease↗
PubMed1988

The NINCDS-ADRDA Work Group criteria for the clinical diagnosis of probable Alzheimer's disease: a clinicopathologic study of 57 cases.

Neuropathologic confirmation is required to validate the NINCDS-ADRDA Work Group criteria for the clinical diagnosis of Alzheimer's disease (AD). Neuropathologic inclusion and exclusion criteria for AD, however, are not uniform. The purpose of this investigation was to examine the confirmation rate for the Work Group criteria against differing neuropathologic criteria for AD. The sample consisted of 57 cases, 22 of which had received a clinical diagnosis of AD. Nine neuropathologic criteria for AD were applied in a blind fashion to each of the 57 cases. Our results indicated that, depending on the neuropathologic criteria applied, the clinicopathologic agreement ranged from 64% to 86%. These findings demonstrate the need for universally accepted neuropathologic and clinical criteria for AD.

Aged↗
PubMed1988

Demographic and medical characteristics of adult head injuries in a Canadian setting.

This study provides demographic and medical information about patients admitted with head injuries to Sunnybrook Medical Centre, Toronto, Ont., in 1978 and in 1982. Data are presented about patient age and sex, type and cause of accident, length of stay, extracranial complications, severity of head injury, frequency of use of various neurodiagnostic techniques and type of discharge placement. The costs of hospitalization for such patients, both in the Sunnybrook Medical Centre and for Canada as a whole, are estimated.

Adolescent↗
PubMed1987

Psychometric differentiation of dementia. Replication and extension of the findings of Storandt and coworkers.

In a previous investigation by Storandt and coworkers, a brief battery of four neuropsychological tests was found to accurately distinguish a sample of patients with senile dementia of the Alzheimer type (SDAT) from normal elderly persons. The present study examined the value of these tests in the distinction between SDAT and dementias of other etiologies. Our results replicated those of Storandt and coworkers in that these tests did distinguish normal persons from patients with both SDAT and other dementias. These tests, however, did not accurately differentiate among the dementias. These results indicate that assessment batteries utilizing additional procedures to supplement cognitive testing are indicated to more accurately discriminate among the dementias.

Aged↗
PubMed1987

Aphasia Screening Test performance in patients with lateralized brain damage.

Patients with lateralized stroke (N = 36) or tumor (N = 14) were compared in the frequency of errors on specific test items of the Aphasia Screening Test (Reitan, 1984). Right- and left-hemisphere damaged patients showed a statistically significant difference on only 1 of the 33 items of this measure. When items were categorized according to task type (e.g., spelling, reading, calculation, etc.) only 1 of 9 comparisons was significant. Several possible explanations for the lack of differences are discussed and suggestions offered for potential modifications to this measure.

Adult↗
PubMed1986

The differential diagnosis of Alzheimer's disease: conceptual and methodological issues.

The study of Alzheimer's disease is hampered by insufficient knowledge of its cause. It can best be described as a syndrome whose clinical and pathological features, and their associations over time, need to be more carefully examined. Issues which impede our understanding of this syndrome include the lack of: a singular "gold standard" for its identification; longitudinal studies with appropriate comparison groups and neuropathological follow-up; and standardized multifaceted clinical assessment procedures. Our awareness of the significance of these issues has led us to undertake a large-scale prospective, longitudinal investigation of 399 dementing and normal individuals at Sunnybrook Medical Centre. As a result of problems identified, it is proposed that research efforts across various Canadian centres be coordinated to best utilize available resources and expertise.

Alzheimer Disease↗
PubMed1986

Lateralized brain damage, sex differences, and the Wechsler Intelligence Scales: a reexamination of the literature.

Recent reviews have suggested that males and females show different patterns of intellectual impairment following lateralized brain injury. As the percentage of males in such studies increases, the magnitude of the difference between Verbal and Performance IQs increases. The present review reexamines this literature. Although the association between patient sex, pattern of intellectual deficit, and lateralized brain injury is reconfirmed for studies which used the Wechsler-Bellevue Intelligence Scale, there was no such relationship in those which used the more recent Wechsler Adult Intelligence Scale. In addition, it is shown that, in studies which used the former measure, the percentage of males may be highly correlated with other variables, a relationship which could have an effect on the pattern of intellectual loss following brain injury.

Adult↗
PubMed1986

Predictors and indicators of quality of life in patients with closed-head injury.

This study examined predictors and indicators of quality of life in 71 patients with closed-head injury (CHI), 2-4 years postinjury. Predictors included premorbid characteristics and acute injury-related data. Indicators included follow-up data, e.g., neuropsychological functioning. Exploratory canonical correlation analyses demonstrated that the combination of the predictor variable, initial Glasgow Coma Scale score, and indicator variables of neuropsychological data in the areas of motor functioning, memory, and constructional ability were related most strongly to quality of life as reported by the patients. Severity of head injury and motor disability also related strongly to quality of life, based on reports by relatives (n = 68) on the Katz Adjustment Scale (Relatives' Form). These findings suggest that quality of life is adversely affected by increased severity of head injury and greater residual motor deficits. Implications of these findings for treatment and recovery are discussed.

Adolescent↗
PubMed1986

Quality of life in patients 2 to 4 years after closed head injury.

This study evaluated quality of life in 78 patients with closed head injury (CHI) 2 to 4 years postinjury. Using both interview data and mean data from the Sickness Impact Profile questionnaire, impaired quality of life was observed in the areas of psychosocial functioning, social role functioning, leisure activities, and, to a lesser extent, physical functioning, during chronic phases of recovery. Relatives and close friends reported by means of the Katz Adjustment Scale that the CHI patients showed a series of negative behavioral symptoms 2 to 4 years postinjury. These data suggest that CHI patients may experience impaired quality of life in a number of domains well beyond the acute postinjury phases. An attempt was also made to compare patients' and relatives' reports of patient quality of life. Preliminary analyses indicated modest correspondence between relatives' and patients' ratings of some areas of postinjury dysfunction, including cognitive and behavioral slowing and social withdrawal.

Activities of Daily Living↗
PubMed1981

A comparison of frequency of abnormal results in neuropsychological vs. neurodiagnostic procedures.

Compared the frequency of abnormal Impairment Index values and abnormal results on neurodiagnostic procedures in patients (N = 102) classified as Brain-damaged, Normal, or Equivocal on the basis of final medical diagnosis. The Impairment Index called a higher percentage of the Brain-damaged Ss abnormal than did any single neurodiagnostic procedure. Although it called a higher percentage of the other two groups abnormal than did the skull X-ray, the Impairment Index did not differ from computed tomography (CT) or the EEG with respect to abnormality rates in those groups. Thus, in this sample of patients, the Impairment Index was more sensitive to brain damage than any neurodiagnostic measure, yet no more likely to call patients in the other two groups abnormal than were CT or the EEG. Limitations of the study and difficulties in conducting this kind of research are discussed.

Adult↗
PubMed1981

Problem-solving task performance in brain-damaged subjects.

Investigated the relationship between the Halstead Category Test and the Wisconsin Card Sorting Test. A correlational analysis revealed a statistically significant but modest relationship between the two variables in separate samples of brain-damaged and non-brain-damaged individuals (N = 156). Thus, in spite of the apparent similarity of the two measures, their relationship is not sufficiently close to suggest that in fact they are measuring the same abilities. However, the combination of hit rates of the two measures and the high base rate of brain dysfunction in the present sample yielded good diagnostic accuracy for decisions with regard to the presence of brain damage.

Adult↗
PubMed1981

Reduced accuracy of classification with a short form of the Speech Sounds Perception Test.

This study attempts to cross-validate the accuracy in classification of Golden and Anderson's (1977) abbreviated version of the Halstead Speech Sounds Perception Test. A relatively high correlation was obtained between their short form and the standard long form for a sample of 150 patients, aged 15 to 70 yr. However, the long form was more accurate in discriminating between 31 brain-damaged and 31 nonbrain-damaged patients. These results suggest that the use of the short form of this test may reduce accuracy of classification.

Adolescent↗