Biomedical subjects

G A Chase

Publications and source records attributed to G A Chase.

At least 73 records · Page 4Linked to original sources

PubMed1990

A family history study of neuropsychiatric disorders in the adult siblings of autistic individuals.

The family history method was used to obtain developmental, social, and psychiatric histories on the 67 adult siblings of 37 autistic probands. Two of 67 siblings (3.0%) were autistic, three siblings (4.4%) had severe social dysfunction and isolation, 10 (15%) had cognitive disorders, and 10 (15%) had received treatment for affective disorder. This study is the first to investigate the frequency of disorders in the adult siblings of autistic probands. These results suggest aggregation of a variety of neuropsychiatric disorders in the siblings of autistic individuals.

Adolescent↗

PubMed1990

Association between family history of affective disorder and the depressive syndrome of Alzheimer's disease.

For each of 41 index patients with probable Alzheimer's disease and a first episode of major depression and 71 nondepressed Alzheimer's disease patients, two first-degree relatives were interviewed by a rater blind to presence or absence of depression in the proband. The depressed patients had significantly more first- and second-degree relatives with depression than did control subjects. The lifetime risk for major depression, adjusted for differences in age distribution, was significantly greater in first-degree relatives of index patients, suggesting that depression in Alzheimer's disease is genetically related to primary affective disorder. Alzheimer's disease may be useful for studying aspects of depressive pathophysiology.

Age Factors↗

PubMed1990

Psychiatric symptoms and nursing home placement of patients with Alzheimer's disease.

Two hundred ten community-dwelling patients with Alzheimer's disease were examined prospectively by psychiatrists as part of a longitudinal study. Twenty-five of these patients who were institutionalized during the next 3 years were then matched to 25 patients who were not institutionalized, and the groups were compared. The patients who had been institutionalized had higher scores on standardized psychiatric rating scales but not on formal neuropsychological tests of cognition. These results suggest that potentially treatable (noncognitive) behavioral and psychiatric symptoms are risk factors for institutionalization, and that treating these symptoms might delay or prevent institutionalization of some patients.

Aged↗

PubMed1989

Ventricle-brain ratio, computed tomographic density, and brain area in 50 schizophrenics.

A sample of 50 DSM-III-diagnosed schizophrenics (mean age, 34 years) intentionally biased to contain a relatively high proportion of persistently unemployed persons was compared with a sample of 87 normal volunteers on three computed tomographic measures. These were lateral ventricle-brain ratio, regional brain computed tomographic density values, and brain slice area. Images were made with the same computed tomographic scanner and identical scan parameters. Computed tomographic data were assessed blindly using a computer-linked image array processor and electronic planimeter. Ventricle-brain ratios were significantly higher in schizophrenics, with 28% of the patient sample exceeding 2 SDs of the control mean. Brain area measures were not associated with an enlarged ventricle-brain ratio. Contrary to our prediction, ventricular enlargement was unassociated with most negative symptom ratings, but was correlated with the absence of positive symptoms. A history of abnormal delivery and the presence of left-handedness were significant predictors of an enlarged ventricle-brain ratio on multiple regression analysis. Schizophrenics had a significantly smaller brain slice area compared with normal controls, a finding not attributable to height differences between groups. Brain slice area was inversely correlated with computed tomographic brain density across all subjects. After correction of computed tomographic density values for area using a linear regression model, no significant regional density differences were detectable between normal controls and schizophrenics. Within normal controls there was a significant relationship between social class and brain slice area, but not ventricle-brain ratio.

Adult↗

PubMed1989

Simulation of Huntington's disease onset.

Previous investigators have noted that the type of sampling scheme used to study the natural history of Huntington's disease can affect the observed age of onset distribution. Simulated data are presented to demonstrate that bias is introduced when onset characteristics derived from prevalence samples (i.e., samples of affected individuals alive in the population) are used to evaluate cofactors of disease onset and to compute genetic risk estimates for persons "at risk" of developing the disease. This study demonstrates that prevalence sampling underestimates the proportion of Huntington's disease cases in the population with later onset ages. Using plausible values for onset time, duration, and life expectancy, simulation results suggest that the paternal transmission effect on Huntington's disease onset is overestimated when based on prevalence data.

Adolescent↗

PubMed1989

A chart review study of late-onset and early-onset schizophrenia.

This chart review study compared 54 schizophrenic patients with onset of illness after age 45 years to 54 young and 22 elderly patients with early-onset schizophrenia (before age 45). The index group was more likely to have visual, tactile, and olfactory hallucinations; a greater number of different types of hallucinations; persecutory delusions; and premorbid schizoid personality traits, and was less likely to have thought disorder and affective flattening, than was either comparison group. Among the two elderly groups, index patients had more auditory and visual sensory impairment. Nearly half (48.1%) of the index patients responded to neuroleptic treatment with complete remission.

Adolescent↗

PubMed1988

Linkage studies of Best's macular dystrophy.

Genetic linkage studies are presented for nine kindreds with Best's vitelliform macular dystrophy (BVMD). This condition is an autosomal dominant macular dystrophy with reduced penetrance and highly variable expressivity. Asymptomatic carriers were identified with electro-oculography, fundus photographs and fluorescein angiography. Blood and saliva specimens were obtained from informative family members and genotyped for 26 polymorphic genetic traits. No firm evidence was found for linkage between BVMD and 18 informative markers; the highest positive lod score was z = 0.57 for GPT1 at a recombination fraction of theta = 0.30. An atypical form of vitelliform macular dystrophy (VMD-1) is linked to GPT1 (theta less than 0.05) and is provisionally assigned to chromosome 16pter-p11. Our data are not sufficient to rule out loose linkage for GPT1 and BVMD. Thus we were not able to determine whether BVMD and VMD-1 are allelic mutations or separate genetic disorders. Additional linkage and gene mapping studies of these loci and BVMD (as well as other atypical forms of macular dystrophy) would be useful to further delineate these disorders.

Gene Expression Regulation↗

PubMed1987

Delivery of fertility control services by male and female obstetrician-gynecologists.

Sex differences in the delivery of fertility control services were explored in a national survey of 1420 recently trained obstetrician-gynecologists in active practice. Women were found to be more likely than men to provide abortion services but less likely than men to provide amniocentesis and certain infertility services. Women were found to contribute less than their proportionate share of two services for which volume was measured: artificial inseminations and sterilizations. Physician gender, however, was a less important predictor of volume of sterilizations delivered than were a set of practice-related variables. Overall our findings suggest that the increased representation of women among obstetrician-gynecologists could influence the delivery of a few specific services.

Family Planning Services↗

PubMed1987

An epidemiologic approach to the evaluation of the effect of inbreeding on prereproductive mortality.

Although many studies report deleterious effects of inbreeding on prereproductive mortality (death before age 20 years), such effects are usually measured in terms of genetic load, a concept much debated in the literature. To evaluate the public health impact of inbreeding on prereproductive mortality in terms of relative and attributable risks, the authors reviewed 31 studies with 294 observations comparing various stages of infant and child mortality in offspring of unrelated parents with offspring of first cousin, first cousin once removed, and second cousin marriages, respectively. Compared with offspring of unrelated parents, offspring of first cousin marriages have a higher risk of prereproductive mortality (median relative risk (RR) = 1.41, signed-rank test, p less than 0.01). Offspring of first cousin once removed and second cousin marriages had median relative risks of 1.16 and 1.26, respectively. Countries with relatively higher rates of consanguineous marriages (greater than 5%) had lower median relative risks than did countries with lower consanguinity rates. Also, the higher the mortality rate in the population, the lower the effect of consanguinity (median relative risk). Because of the rarity (less than 5%) and declining trends of consanguineous marriages in many places of the world, and because of their modest effect on prereproductive mortality (RR less than 2.0), it can be shown that the attributable risk of prereproductive mortality due to consanguineous marriages is less than 5%. Except for a few places with very high inbreeding levels, inbreeding has a minor impact on mortality in the prereproductive period.

Consanguinity↗

PubMed1987

Inbreeding and prereproductive mortality in the Old Order Amish. I. Genealogic epidemiology of inbreeding.

Epidemiologic patterns of inbreeding in the Old Order Amish were investigated using a unique genealogic registry of Lancaster County, Pennsylvania, Amish that contains information on 8,163 marriages, dating back to the time of the pioneer migrants in the 1700s and spanning more than 10 generations. The kinship coefficient for each marriage was computed using the path method of tracing common ancestors in the multigenerational pedigrees. Because of extensive genealogic connections, mean kinship coefficients and the proportion of related marriages have increased significantly over time, from 0.004 and 37%, respectively, for marriages before 1850 to 0.012 and 98%, respectively, for marriages after 1950. Demographic factors related to higher kinship levels include young age at marriage, large sibship size for both husband and wife, husband being a farmer, and marriages occurring in the marriage season (November or December). The rise in inbreeding levels in the Amish over time can be uniquely contrasted with the decline in inbreeding in most areas of the world. Furthermore, because some of the demographic factors related to high inbreeding levels may be associated with levels of mortality, such factors have to be taken into account when studying the effects of inbreeding on mortality in the Amish. This study uses an epidemiologic approach to the evaluation of inbreeding patterns in a population over time.

Consanguinity↗

PubMed1987

Inbreeding and prereproductive mortality in the Old Order Amish. III. Direct and indirect effects of inbreeding.

Direct and indirect (mediated by biologic factors) effects of inbreeding on prereproductive mortality (death before age 20 years) were investigated in a case-control study conducted in the Lancaster County, Pennsylvania, Old Order Amish. A total of 211 cases of prereproductive death between 1969 and 1980 and 213 live controls were compared for differences in inbreeding coefficients, congenital malformations, birth weight, gestational age, birth complications, and other demographic factors, obtained by linking cases and controls to vital records and the Amish genealogic registry dating back to the 1700s. Inbreeding coefficients (F) for cases and controls were computed using the path method of tracing common ancestors in the multigenerational pedigrees. Close inbreeding (F greater than or equal to 1/64) was a significant risk factor for prereproductive mortality; odds ratio = 1.55. Using the log-linear model, the effect of close inbreeding on mortality was found to be mediated by three indirect casual mechanisms: Regardless of case-control status, inbreeding was significantly related to congenital malformations (recorded at birth), intrauterine growth retardation (birth weight less than 10th percentile for gestational age), and the occurrence of other deaths in the sibship. In turn, each of these factors was independently related to mortality regardless of inbreeding. No significant direct effect of inbreeding remained after adjustment for these factors. There were no effects of inbreeding on prematurity (less than 37 weeks), or birth complications. This study suggests that inbreeding increases the risk of prereproductive mortality by increasing the risk of intrauterine growth retardation and congenital malformations but not prematurity. The log-linear model provides a useful approach to the analysis of direct and indirect risk factors using biologic mechanisms.

Congenital Abnormalities↗

PubMed1987

Prenatal screening and pregnant women's attitudes toward the abortion of defective fetuses.

We studied the attitudes of 490 pregnant women toward the abortion of defective fetuses. Three hundred of these women were participating in a prenatal screening program for neural tube defects. Although theoretical accounts of the effects of behavior on attitude would suggest that participation in a screening program would affect abortion attitudes, evidence in support of such an association was weak. The overwhelming majority of women, regardless of whether they had participated in the screening program, believed that women are justified in having an abortion in the face of fetal abnormality. There was a sharp increase in the number of screening program participants who said they would have an abortion when the probability of the fetus being affected with a neural tube defect rose from 95 per cent to 100 per cent.

Abortion, Induced↗

PubMed1987

Huntington disease in Maryland: clinical aspects of racial variation.

In a Maryland survey of Huntington disease, the prevalence in blacks was unexpectedly high and equal to that in whites. Age at onset was earlier in blacks, and their clinical features, at all ages at onset, were similar to those seen in juvenile-onset Huntington disease. Blacks had more severe bradykinesia and abnormalities of eye movement and less frequent psychiatric disorder, particularly depression.

Adolescent↗

PubMed1986

The abridged census method as an estimator of lifetime risk.

The abridged census estimator, also known as Weinberg's shorter method, is a device used to estimate lifetime incidence from the observed age distribution of a population at risk coupled with data on the current prevalence of a mental disorder. This method, which still enjoys considerable popularity, should have been replaced many years ago by more accurate techniques for making such estimates using similar information. In particular, the abridged census method uses the assumption that the remaining life expectancy of incident cases equals that of non-cases. This assumption is likely to lead to an underestimate of the lifetime risk. Two examples are presented from published literature which illustrate some problems encountered with the use of the abridged census method. Some alternative estimation methods are presented which can be implemented using only a hand calculator and which lead to more accurate results.

Alzheimer Disease↗

PubMed1986

Sex differences in the practice patterns of recently trained obstetrician-gynecologists.

Sex differences in practice patterns, as modified by family roles, are investigated in a national survey of 1420 active obstetrician-gynecologists who graduated from medical school between 1974 and 1979. Women are more likely than men to be practicing in multispecialty groups, and men are more likely than women to be practicing in obstetrics-gynecology partnerships. On average, men and women report working over 60 hours per week. In all practice arrangements except academic medicine, women work fewer total hours per week, although the differences are small and translate into significantly fewer patient encounters than men in only two practice arrangements: partnerships and multispecialty groups. When marital status and presence of children under age 18 are controlled, significant sex differences in hours worked remain only for married respondents with children. Family roles have an opposite effect on hours of work reported by men and women, decreasing the number of hours worked by women and increasing the number worked by men.

Adult↗

PubMed1986

Epidemiological approach to the evaluation of genetic screening in the workplace.

Using several examples of genetic marker and disease associations in the workplace, the authors have applied formulas to estimate the sensitivity, specificity, and positive predictive value (PPV) of screening for these markers. Sensitivity, specificity, and PPV are affected independently by characteristics of the population being screened, ie, the genetic marker frequency, the disease frequency, and the magnitude of the relative risk (R). For a given disease frequency, when the genetic marker is less frequent than the disease, PPV increases with relative risk, although sensitivity remains low. When the genetic marker is more frequent than the disease, PPV remains low while sensitivity increases with R. When marker and disease frequencies are equal, PPV and sensitivity are equal and increase with R. However, when the disease frequency is very low, R must approach 100 before PPV or sensitivity approaches 50%. These relationships may be used effectively in the decision whether to implement a screening program in the workplace.

Disease Susceptibility↗

PubMed1986

The impact of the Mississippi Improved Child Health Project on prenatal care and low birthweight.

A quasi-experimental, nonequivalent control group design was used to evaluate the Improved Child Health Projects in northwest Mississippi (ICHP1 and ICHP2). Control counties were selected for each project that on average were similar to ICHP counties on racial composition, median family income in 1970 and 1980, and number of births in 1978-79. The study population comprised all resident births in the ICHP and control counties during a pre-ICHP period (1975-78) and the ICHP period (1979-81). The percentage of women with adequate prenatal care rose between the two periods for all counties; the rise was greater for the study than for the control counties for ICHP1; the reverse was found for ICHP2. For both projects, the low birthweight rate remained constant in the pre-ICHP and ICHP periods for the study and control counties. Adjustment for changes in the childbearing characteristics between the two periods did not alter these results. Community involvement in its development and coordination may explain ICHP1's impressive rise in the use of prenatal care.

Child Health Services↗

PubMed1986

Covariate-dependent genetic counseling in Huntington's disease.

From detailed study of a population-based sample of active cases of Huntington's disease it is known that the age of onset of Huntington's disease is strongly affected by whether Huntington's disease was inherited from mother or father. Standard methods for genetic counseling risk computations use age of unaffected consultant as a covariate affecting the quoted risk, but no other covariates are used in these risk computations. We demonstrate the feasibility of using a proportional hazards approach to computation of the penetrance function which in turn enables a risk to be computed incorporating other covariates besides age of consultant. When there is only one significant covariate other than age, direct estimation of age-of-onset distributions corresponding to various values of the covariate also gives useful results. Our analyses show that genetic counseling risks based on covariates are feasible to compute and offer additional accuracy to the recipient of the information.

Adult↗