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Biomedical subjects

G Downey

Publications and source records attributed to G Downey.

32 records · Page 2Linked to original sources
PubMed1991

Twin studies of psychopathology: why do the concordance rates vary?

Many current discussions of hereditary factors in psychopathology focus on twin studies as the primary source of evidence supporting the importance of genetic determinants. In summarizing the results of these studies, authors often derive estimates of concordance rates by collapsing across studies and presenting mean or median rates. This practice implicitly assumes that the concordance rates yielded by different studies represent equally reliable estimates of the population mean. The present study evaluates the validity of this assumption. Reports of twin studies of schizophrenia and affective disorder were reviewed. A meta-analysis was conducted to examine the influence of methodological factors on concordance rates. Analyses indicated that both sample-selection and zygosity-determination procedure are systematically associated with concordance rates. For schizophrenia, MZ concordance rates are significantly lower when samples are selected from a twin register as opposed to a psychiatric facility. Lower MZ concordance rates are also yielded by studies that employ laboratory procedures to determine zygosity. Implications of the findings for future research are discussed.

Affective Disorders, Psychotic↗
PubMed1990

The effects of familial risk factors on social-cognitive abilities in children.

Consistent with the results of previous studies of children with depressed parents, the present investigation of social-cognitive abilities with schizophrenic parents yields no evidence of deleterious effects of parental psychopathology. Similarly, maltreatment was not associated with social-cognitive deficits. The central conclusion to be drawn from these results is that social-cognition does not mediate the effects of these risk factors on child behavior, although social-cognition may serve as a moderator.

Adolescent↗
PubMed1990

Reconsidering the attribution-adjustment relation following a major negative event: coping with the loss of a child.

Field studies have not yet conclusively established how attributions affect adjustment to unanticipated traumatic events. This may be due, in part, to the adoption of several untested assumptions in most prior research. It has usually been assumed that attributional issues are important to people who experience a traumatic event, that such concern is adaptive, and that specific attributions (e.g., self-blame) influence subsequent adjustment. These assumptions were tested with longitudinal data collected over 18 months from 124 parents whose child died of Sudden Infant Death Syndrome. By 3 weeks postloss, 45% of parents were not concerned with attributional issues. These parents were less distressed and less likely to blame themselves or others for the death. Longitudinal analyses did not support the assumption that attributions influence subsequent adjustment. Rather, attributions to onself or others appear to be symptomatic of distress.

Adaptation, Psychological↗
PubMed1990

Children of depressed parents: an integrative review.

This article reviews the various literatures on the adjustment of children of depressed parents, difficulties in parenting and parent-child interaction in these families, and contextual factors that may play a role in child adjustment and parent depression. First, issues arising from the recurrent, episodic, heterogeneous nature of depression are discussed. Second, studies on the adjustment of children with a depressed parent are summarized. Early studies that used depressed parents as controls for schizophrenic parents found equivalent risk for child disturbance. Subsequent studies using better-defined samples of depressed parents found that these children were at risk for a full range of adjustment problems and at specific risk for clinical depression. Third, the parenting difficulties of depressed parents are described and explanatory models of child adjustment problems are outlined. Contextual factors, particularly marital distress, remain viable alternative explanations for both child and parenting problems. Fourth, important gaps in the literature are identified, and a consistent, if unintentional, "mother-bashing" quality in the existing literature is noted. Given the limitations in knowledge, large-scale, long-term, longitudinal studies would be premature at this time.

Adaptation, Psychological↗
PubMed1990

Activation of mechanical responses in leukocytes.

Different kinds of leukocytes undergo cytoskeleton-dependent mechanical responses associated with their specific physiological functions. We have investigated cellular stiffening of several types of leukocytes using a method which measures the force resisting cellular indentation. We have found that lymphocytes stiffen in response to crosslinking cell surface antigens in a process associated with the much studied capping and patching processes. Further studies of myosin-deficient mutants of the ameba Dictyostelium discoideum suggest that this stiffening process results from a myosin dependent contractile process. Rat basophilic leukemia cells and pancreatic islet cells stiffen when triggered to secrete. The function of these cytoskeleton dependent processes is now unknown, but, at least in the islet cells, may be related to a regulation of the rate of secretion. Primary neutrophils stiffen in response to the chemotactic agent, fMet-Leu-Phe. This stiffening may be responsible for retention of these cells in the pulmonary microcirculation during response to inflammation. These observations pose the challenge of determining the structural basis, mechanism, and physiological function of each of these cellular responses.

Animals↗
PubMed1989

Network television news stories about suicide and short-term changes in total U.S. suicides.

A number of recent reports have documented a positive association between mass media news stories about suicide and subsequent short-term increases in total U.S. suicides. However, the estimated magnitude of this association varies considerably across these published reports and tends to be smaller in the more comprehensive studies. A detailed investigation of all network television suicide news stories broadcast between January 1, 1973, and December 31, 1984, was undertaken to resolve this inconsistency. The information about television coverage of suicides was more comprehensive than in previous studies. The analyses show that there was no reliable association between news stories and suicides among adults at any time over the 12 years investigated. A reliable association existed among teenagers between 1973 and 1980. This association reversed in 1981, however, and the relative risk of suicide associated with network news stories was consistently less than 1.0 through the end of the study period.

Adolescent↗
PubMed1989

The effects of parental psychopathology and maltreatment on child behavior: a test of the diathesis-stress model.

Past research on risk factors in child development has tended to focus on 1 risk factor rather than examining the effects of multiple factors simultaneously. The present research examines the main and interactive effects of parental psychopathology (schizophrenia, psychiatric control, and normal control) and maltreatment on child behavior. Child aggression, delinquency, and social withdrawal were assessed at 2 times so that the effects of risk factors on behavioral change could also be examined. The results indicate significant relations between the risk factors and child behavior. Most notably, parental psychiatric status and maltreatment interacted significantly, such that offspring of schizophrenic parents from maltreating families showed increases in externalized behavior problems over time. These results support a diathesis-stress model of psychopathology.

Aggression↗
PubMed1988

Clustering of teenage suicides after television news stories about suicides: a reconsideration.

A recent study reported a significant increase in teenage suicides after television newscasts about suicide in the period 1973-1979 and suggested that the increase might have resulted from an imitative effect of television. In the present study, the authors found no significant association between newscasts and subsequent teenage suicides over the period 1973-1984. Although teenage suicides increased after newscasts in 1973-1980, the authors identify reasons why this increase is not consistent with an imitative effect of television. Furthermore, during 1981-1984 teenage suicides decreased after newscasts about suicide; the reversal differs significantly from the association before 1981.

Adolescent↗
PubMed1976

Endorphin activity in anterior, intermediate, and posterior pituitary.

The content of endogenous morphine-like substance in bovine pituitary and brain was determined by an opiate radioreceptor assay. The intermediate lobe was most concentrated in activity and the brain least concentrated. Most of the endorphin is obtained in a 120 000 g-min fraction from pituitary or brain homogenates.

Animals↗