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Biomedical subjects

G A Chase

Publications and source records attributed to G A Chase.

At least 55 records · Page 3Linked to original sources
PubMed1993

The etiology of autism: pre-, peri- and neonatal factors.

OBJECTIVE: To examine pre-, peri-, and neonatal factors in autism using composite optimality scores. METHOD: Pre-, peri-, and neonatal composite optimality scores were examined in 39 autistic subjects and 39 randomly matched sibling controls using a modification of the Gillberg Optimality Scale (Modified-GOS). Scores were based on best-estimate ratings of maternal interviews and medical records. Rules for best-estimate ratings were derived from a study of agreement between these two sources. RESULTS: Significant differences in optimality between autistic probands and their siblings were not present after adjustment for "maternal parity." Examination of specific variables revealed that only maternal parity differed significantly between autistic subjects and randomly matched sibling controls, reflecting an excess of first and fourth born among the autistic subjects. CONCLUSION: The findings of this study suggest that previous reports of an association between optimality and autism are a result of failure to adjust for birth order.

Adolescent↗
PubMed1993

Measuring physicians' tolerance for ambiguity and its relationship to their reported practices regarding genetic testing.

Despite uncertainties in medicine, attempts to study physicians' tolerance for uncertainty have been few, and limited by the measurement instruments available. This paper describes development of a modified tolerance for ambiguity (TFA) scale, and correlates it with several physician characteristics and reported behaviors. Eighteen TFA items were included in a national survey of physicians' knowledge and attitudes about genetic testing. Sixty-five percent (n = 1,140) of 1,759 obstetricians, pediatricians, internists, family practitioners, and psychiatrists responded. After psychometric analyses, the scale was reduced to 7 items, demonstrating an acceptable reliability (Cronbach's alpha = .75). TFA was higher among psychiatrists than other specialties, among those who were older when they graduated from medical school, and among those willing to offer a new low-cost, accurate predictive test when none of their colleagues do. TFA was lower among those who indicated that attendance at religious services was important, among those who would make a recommendation to their patients regarding pregnancy termination after prenatal diagnosis, and among those who would withhold negative genetic test results. Future research is needed on the scale itself, and to assess factors affecting TFA, such as its susceptibility to modification, and its potential association with clinical practice in other areas of medicine that are characterized by ambiguity.

Abortion, Therapeutic↗
PubMed1993

Volumetric MRI changes in basal ganglia of children with Tourette's syndrome.

To define the site of pathology in Tourette's syndrome (TS), we performed a volumetric MRI study of basal ganglia structures and lateral ventricles on 37 children with this disorder and 18 controls. There were no statistically significant differences in the size of the right or left caudate, putamen, globus pallidus, or ventricles in these populations. In contrast, there were significant differences for measures of symmetry in the putamen and the lenticular region. Virtually all controls (17 right- and one left-handed) had a left-sided predominance of the putamen, whereas in 13 of 37 TS subjects, a right predominance exceeded that of any control. Statistical comparisons among TS patients, with (n = 18) or without (n = 19) attention-deficit hyperactivity disorder (ADHD), and controls showed significant differences for the volume of the left globus pallidus and for lenticular asymmetry. Post hoc evaluations showed that in the TS + ADHD group, the volume of the left globus pallidus was significantly smaller than the volume of the right and that lenticular asymmetry was due to a greater right-sided predominance in the TS+ADHD group. This study lends further support to proposals that claim the basal ganglia is involved in the pathogenesis of TS and also suggests that the comorbid problem of ADHD is related to regional changes that differ from those primarily associated with tics.

Adolescent↗
PubMed1993

Improving response rates through incentive and follow-up: the effect on a survey of physicians' knowledge of genetics.

OBJECTIVES: This study assessed efforts to increase response rates to a mailed physician survey and examined whether, as a result, nonresponse bias was reduced. METHODS: Randomly selected physicians and geneticists were mailed a questionnaire concerning genetics knowledge and attitudes. In the final but not the pilot survey, a $25 incentive and intensive follow-up were used to increase the response rate. RESULTS: The response rate from physicians in the final survey was 64.8% (n = 1140), compared with 19.6% in the pilot test (n = 69). Sample representatives in sociodemographic and practice characteristics was improved by follow-up. Respondents recruited with more difficulty did not differ on the principal outcome variable, genetics knowledge, except on one subscore. Pilot study and final survey respondents did not differ in knowledge. CONCLUSIONS: Although the effect of increased response rates on the principal outcome variable in this study was minimal, this may not be the case for other studies. Every effort should be made to attain as high a response rate as is practical and to establish that respondents are representative of the population being sampled.

Adult↗
PubMed1993

Anticipation in bipolar affective disorder.

Anticipation refers to the increase in disease severity or decrease in age at onset in succeeding generations. This phenomenon, formerly ascribed to observation biases, correlates with the expansion of trinucleotide repeat sequences (TNRs) in some disorders. If present in bipolar affective disorder (BPAD), anticipation could provide clues to its genetic etiology. We compared age at onset and disease severity between two generations of 34 unilineal families ascertained for a genetic linkage study of BPAD. Life-table analyses showed a significant decrease in survival to first mania or depression from the first to the second generation (P < .001). Intergenerational pairwise comparisons showed both a significantly earlier age at onset (P < .001) and a significantly increased disease severity (P < .001) in the second generation. This difference was significant under each of four data-sampling schemes which excluded probands in the second generation. The second generation experienced onset 8.9-13.5 years earlier and illness 1.8-3.4 times more severe than did the first generation. In additional analyses, drug abuse, deaths of affected individuals prior to interview, decreased fertility, censoring of age at onset, and the cohort effect did not affect our results. We conclude that genetic anticipation occurs in this sample of unilineal BPAD families. These findings may implicate genes with expanding TNRs in the genetic etiology of BPAD.

Adult↗
PubMed1992

Quantitative changes in mesial temporal volume, regional cerebral blood flow, and cognition in Alzheimer's disease.

Twenty-six patients with moderately severe Alzheimer's disease (AD) and 16 normal control subjects were studied using either quantitative magnetic resonance imaging (MRI) measures of mesial temporal atrophy (15 patients with AD and 16 normal control subjects) and/or quantitative radioactive iodine 123-N-isopropyl-iodoamphetamine single-photon emission computed tomography (SPECT) assessment of regional cerebral blood flow (20 patients with AD and eight normal control subjects). Nine individuals with AD and eight normal control subjects underwent both structural and functional imaging. On MRI, patients and controls were best discriminated using left amygdala and entorhinal cortex volumes, and on SPECT they were best discriminated by relative left temporoparietal cortex blood flow. Combining these MRI and SPECT measures yielded 100% discrimination. Relative left temporoparietal SPECT regional cerebral blood flow and left superior temporal gyral MRI volume correlated best with severity of cognitive deficit in patients with AD. Mesial temporal MRI atrophy exceeded generalized cerebral shrinkage. Both SPECT and MRI regional changes accorded with areas known to be affected by AD neuropathology.

Aged↗
PubMed1992

Putamen volume reduction on magnetic resonance imaging exceeds caudate changes in mild Huntington's disease.

The characteristic pathological features of Huntington's disease (HD) are neostriatal atrophy and neuronal loss. Although neuroradiological studies often show caudate atrophy in patients with moderate HD, frequently no caudate atrophy is found early in the illness. There have been no quantitative reports to date on in vivo putamen volume measures in mild HD, although the structure is known to be neuropathologically involved in the illness. We measured volumes of caudate nucleus and putamen and bicaudate ratios (BCR) from magnetic resonance images, blind to diagnosis, in 15 patients with mild HD and 19 age- and sex-matched control subjects using a computerized image analysis system. The region showing greatest atrophy was the putamen, which was reduced 50.1% in mean volume in HD patients compared with control subjects (p less than 0.000001). In contrast, caudate volume was reduced 27.7% (p = 0.004). BCR was increased 28.5% in HD patients (p = 0.0002). Discriminant function analysis was 94% effective in identifying the diagnostic group based on putamen volume alone, whereas caudate measures had considerable overlap. Correction of putamen volume for head size led to 100% separation by group. Putamen measures and BCR correlated with neurological examination scores but caudate volume did not. Volumetric measurement of putamen is a more sensitive indicator of brain abnormalities in mild HD than measures of caudate atrophy.

Adult↗
PubMed1992

Social language use in parents of autistic individuals.

Social language use (pragmatics) in parents of autistic individuals and controls was compared. Autism parents displayed atypical pragmatic behaviours more often than controls. Preliminary factor analysis suggested three parsimonious groupings of pragmatic abnormalities: Disinhibited Social Communication, Awkward/Inadequate Expression, and Odd Verbal Interaction. The pragmatic features observed in some autism parents are milder but conceptually similar to the social language deficits of autism. Possible reasons for familial aggregation of pragmatic language deficits are discussed.

Autistic Disorder↗
PubMed1992

Discriminant validity of a reduced set of Mini-Mental State Examination items for dementia and Alzheimer's disease.

Linear discriminant analysis was used to construct a series of discriminant functions including subsets of demographic variables and Mini-Mental State Examination item responses for a case series and a population sample. A 9-item discriminant function including the variables for time orientation, recall, calculation, copying a figure, age, writing, 3-step command, naming, and race distinguished demented subjects from community controls with 91% sensitivity and 88% specificity. The same discriminant function classified Alzheimer's disease patients and controls with 96% sensitivity and 98% specificity. This discriminant function has been cross-validated as a potential screening instrument for Alzheimer's disease in a community-based sample.

Aged↗
PubMed1992

Visual hallucinations in patients with macular degeneration.

OBJECTIVE: This study was undertaken to determine the prevalence of visual hallucinations in patients with macular degeneration, describe such hallucinations phenomenologically, and possibly determine factors predisposing to their development. METHOD: Using a case-control design, the authors screened 100 consecutive patients with age-related macular degeneration for visual hallucinations. Each patient with visual hallucinations was matched to the next three patients without hallucinations. The patients and comparison subjects were compared in terms of scores on the Beck Depression Inventory, Eysenck Personality Questionnaire, Telephone Interview for Cognitive Status, and a structured questionnaire including demographic characteristics, family history, and medical and psychiatric history. Ophthalmologic data were obtained by chart review. RESULTS: Of the 100 patients, 13 experienced visual hallucinations. Four variables were significantly associated with having hallucinations: living alone, lower cognition score, history of stroke, and bilaterally worse visual acuity. Hallucinations were not associated with family or personal history of psychiatric disorder or with personality traits. In 11 (84.6%) of the 13 patients, the hallucinations had begun in association with an acute change in vision. CONCLUSION: These results indicate that visual hallucinations are prevalent among patients with macular degeneration. They appear unrelated to primary psychiatric disorder. The predisposing factors of bilaterally worse vision and living alone support an association with sensory deprivation, while history of stroke and worse cognition support a decreased cortical inhibition theory.

Aged↗
PubMed1991

Platelet serotonin, a possible marker for familial autism.

Serotonin (5HT) levels in platelet-rich plasma were measured in 5 autistic subjects who had siblings with either autism or pervasive developmental disorder (PDD), 23 autistic subjects without affected siblings, and 10 normal controls. The 5HT levels of autistic subjects with affected siblings were significantly higher than probands without affected siblings, and autistic subjects without affected siblings had 5HT levels significantly higher than controls. Differences in 5HT levels remained significant after adjustment for sex, age, and IQ. These results suggest that 5HT level in autistic subjects may be associated with genetic liability to autism.

Adolescent↗
PubMed1991

Psychiatric disorders in the parents of autistic individuals.

Eighty-one parents of 42 autistic probands and 34 parents of 18 Down syndrome probands were examined using a semistructured, investigator-based version of the Schedule for Affective Disorders and Schizophrenia Lifetime Version to estimate the lifetime risk of psychiatric disorder. The lifetime prevalence rate of anxiety disorder was significantly greater in parents of autistic probands than in parents of Down syndrome probands. The lifetime prevalence rate of major depressive disorder, while not significantly different in cases and controls, may be high in the parents of autistic probands (27%) in comparison with populations rates.

Anxiety Disorders↗
PubMed1991

Physician practices in the diagnosis of dementing disorders.

Because there are both treatable and untreatable causes of dementia, the physician's ability to conduct (or refer a patient for) a differential diagnosis could have a profound effect on health outcomes for patients and on health care costs. This study was undertaken to assess physician practices with regard to the diagnosis of dementing disorders. Data from 53 physicians (a response rate of 48%) in several specialties were obtained from a self-administered mail questionnaire. Results indicate that the majority of physicians provided history taking, physical examination, and neurological examination. Physicians were more likely to refer patients for psychiatric and neuropsychological examinations than to provide these services themselves. The results also point to deficiencies in two key areas: the use of formal, published diagnostic criteria, and the use of mental status and cognitive function tests. Over 75% of physicians surveyed did not use either DSM-III or NINCDS-ADRDA diagnostic criteria, and 42% of physicians did not provide any mental status tests themselves. The need for continuing education to close knowledge gaps is emphasized.

Aged↗
PubMed1991

Impact of Medicare payment policy on home health resources utilization.

In this study, the association between Medicare regulations and the provision of public home health care is examined. Medicare clients were compared with non-Medicare groups of those 65 years of age or over and those under 65. Results suggested that both age- and payer-related factors contribute to utilization of services. Older patients showed greater need for chronic illness care relative to younger patients; however, Medicare patients used fewer resources and had poorer outcomes relative to older non-Medicare patients.

Adult↗
PubMed1991

Adolescent women's contraceptive decision making.

A modified rational decision model incorporating salient events and social influences (particularly from sexual partners) is used to analyze adolescent women's consistent use of oral contraceptives (OCs) over a six-month period. Data are taken from a panel study of 308 clients of an inner-city family planning clinic. Expected OC use was computed for each subject on the basis of subjective expected utility (SEU) theory, and is found in multivariate analyses to be a significant predictor of actual OC use. In addition, variables representing baseline and follow-up partner influences, the salience of pregnancy for the subject, and positive side effects of OCs during the first months of use are found to predict OC use. Partner's support of OC use during follow-up and positive side effects of OCs are found to predict OC use among subjects for whom OC use was not the expected decision according to baseline SEU. Implications of the findings for models of adolescents' contraceptive behavior and for clinicians are discussed.

Adolescent↗