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Old 12-23-05, 12:50 PM
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Abstracts of Nature/Nurture Studies (long)

Okay, I just remembered this morning that I promised some reading on genetic & environmental influences!

I have a tendency to over-rely on textbooks for a lot of my PD info, so this was a good exercise for me. Here are some abstracts of studies I thought were very interesting. They involve various personality disorders and, in some cases, interactions with other disorders. I can probably get a pdf of most of these articles.

Title: Family transmission and heritability of externalizing disorders: A twin-family study
Author: Hicks, Brian M; Krueger, Robert F; Iacono, William G; McGue, Matt; Patrick, Christopher J
Source: Archives of General Psychiatry. Vol 61(9), Sep 2004, pp. 922-928
ISSN: 0003-990X

Abstract: Background: Antisocial behavior and substance dependence disorders exact a heavy financial and human cost on society. A better understanding of the mechanisms of familial transmission for these "externalizing" disorders is necessary to better understand their etiology and to help develop intervention strategies. Objectives: To determine the extent to which the family transmission of externalizing disorders is due to a general vs a disorder-specific vulnerability and, owing to the genetically informative nature of our data, to estimate the heritable vs environmental nature of these transmission effects. Design: We used structural equation modeling to simultaneously estimate the general and specific transmission effects of 4 externalizing disorders: conduct disorder, adult antisocial behavior, alcohol dependence, and drug dependence. Setting: Participants were recruited from the community and were interviewed in a university laboratory. Participants: The sample consisted of 542 families participating in the Minnesota Twin Family Study. All families included 17-year-old twins and their biological mother and father. Main Outcome Measures: Symptom counts of conduct, disorder, the adult criteria for antisocial personality disorder, alcohol dependence, and drug dependence. Results: Transmission of a general vulnerability to all the externalizing disorders accounted for most familial resemblance. This general vulnerability was highly heritable (h=0.80). Disorder-specific vulnerabilities were also detected for conduct disorder, alcohol dependence, and drug dependence. Conclusions: The mechanism underlying the familial transmission of externalizing disorders is primarily a highly heritable general vulnerability. This general vulnerability or common risk factor should be the focus of research regarding the etiology and treatment of externalizing disorders.

Title: Nature and Nurture in Personality Disorders
Monograph Title: Handbook of personology and psychopathology.
Author: Paris, Joel
Source: Strack, Stephen (Ed). (2005). Handbook of personology and psychopathology. (pp. 24-38). Hoboken, NJ, John Wiley & Sons, Inc. xix, 580 pp.

Abstract: (From the chapter) Controversy about the relative importance of nature and nurture in human behavior has raged for generations, and the struggle is far from over. Two conceptual problems have delayed resolution of the nature-nurture problem. First, it is easier to think in a linear than in a multivariate, nonlinear fashion. A second problem derives from a failure to consider psychological phenomena from a systems perspective. Applying general systems theory, we can take the biological roots of behavior into account without being reductionistic. While mental processes ultimately derive from neurochemical and neurophysiological processes, they have emergent properties that cannot be explained at other levels of analysis. These principles can usefully be applied to the understanding of personality disorders. Multivariate approaches and systems theory illuminate complex forms of psychopathology, in which genetic-biological, experiential-psychological, and social factors all play a role. Applying nonlinear models to personality disorder would be consistent with general theories of developmental psychopathology. The stress-diathesis model is a general model for conceptualizing the causes of psychopathology. This model helps us understand how adverse life events contribute to the development of psychopathology.

Title: Etiological Relationships Between Eating Disorder Symptoms and Dimensions of Personality Disorder
Author: Livesley, W John; Jang, Kerry L; Thordarson, Dana S
Source: Eating Disorders: The Journal of Treatment & Prevention. Special Issue: Personality Disorders & Eating Disorders. Vol 13(1), Jan-Feb 2005, pp. 23-35
ISSN: 1064-0266

A preliminary exploration of the etiological factors that may contribute to the relationship between eating disorder symptoms and personality disordergenetic influences were observed on Concern for Overeating, possible non-additive genetic effects on Purging, and substantial additive genetic effects for BMI. Substantial nonshared environmental effects occurred with the Concern with Overeating and Purging scales, and common environmental effects were noted for the Concern with Overeating scale. Personality disorder traits were assessed using the Dimensional Assessment of Personality Pathology-Basic Questionnaire (DAPP-BQ). Phenotypic, genetic, and environmental correlations between the HIQ scales and higher-order personality disorder traits is reported based on a general-population twin sample of 221 pairs. Symptoms of eating disorder, assessed using the Health Information Questionnaire (HIQ), formed 3 factors: Concern for Overeating, Purging, and Body Mass Index (BMI). Modest factors were modest. The strongest relationship was between Concern with Overeating and Emotional Dysregulation. Relationships among DAPP-BQ basic trait scales and eating disorder symptoms were modest and relatively non-specific. The strongest relationships were with the Concern with Overeating scale. Purging also showed a modest relationship with affective lability and self-harm.

Title: Evidence for substantial genetic risk for psychopathy in 7-year-olds
Author: Viding, Essi; Blair, R James R; Moffitt, Terrie E; Plomin, Robert
Source: Journal of Child Psychology and Psychiatry. Vol 46(6), Jun 2005, pp. 592-597
ISSN: 0021-9630

Background: Individuals with early warning signs of life-long psychopathy, callous-unemotional traits (CU) and high levels of antisocial behaviour (AB) can be identified in childhood. We report here the first twin study of high levels of psychopathic tendencies in young children. Methods: At the end of the first school year, teachers provided ratings of CU and AB for 3687 twin pairs from the Twins Early Development Study (TEDS). For the analyses of extreme CU, we selected same-sex twin pairs where at least one twin scored 1.3 or more standard deviations above the mean on the CU scale (612 probands, 459 twin pairs). For the analysis of extreme AB, we selected same-sex twin pairs where at least one twin scored 1.3 or more standard deviations above the mean on AB scale (444 probands, 364 twin pairs). Furthermore, the extreme AB sample was divided into those who were also extreme on CU (children with psychopathic tendencies; 234 probands, 187 twin pairs) and those who did not score in the extreme for CU (children without psychopathic tendencies; 210 probands, 177 twin pairs). Results: DeFries-Fulker extremes analysis indicated that exhibiting high levels of CU is under strong genetic influence. Furthermore, separating children with AB into those with high and low levels of CU showed striking results: AB in children with high levels of CU is under extremely strong genetic influence and no influence of shared environment, whereas AB in children with low levels of CU shows moderate genetic and shared environmental influence. Conclusions: The remarkably high heritability for CU, and for AB children with CU, suggests that molecular genetic research on antisocial behaviour should focus on the CU core of psychopathy. Our findings also raise questions for public policy on interventions for antisocial behaviour.

Title: The Genetic and Environmental Basis of the Relationship Between Schizotypy and Personality: A Twin Study
Author: Jang, Kerry L; Woodward, Todd S; Lang, Donna; Honer, William G; Livesley, W John
Source: Journal of Nervous and Mental Disease. Vol 193(3), Mar 2005, pp. 153-159
ISSN: 0022-3018

Abstract: The clinical phenotype commonly referred to as schizotypy is used in two different ways in psychiatric practice. One usage emphasizes psychosis-proneness where schizotypy is considered part of the schizophrenia spectrum. The other emphasizes personality aberrations and is classed as a personality disorder. The present study provides evidence that schizotypy is a unitary construct and that features like schizophrenia and personality share a common genetic basis. A sample of 102 monozygotic and 90 dizygotic general population twin pairs completed measures of psychosis-proneness and traits delineating personality disorder. Multivariate genetic analyses showed that the observed relationship between psychotic and personality features is caused almost entirely by common genetic factors. Environmental factors appear to be unique to each measure. On the basis of these findings, it is suggested that the environment mediates change in personality function to psychosis as proposed by Meehl's original concept of schizotaxia.

Title: Neurological soft signs in homicidal men with antisocial personality disorder
Author: Lindberg, Nina; Tani, Pekka; Stenberg, Jan-Henry; Appelberg, Bjorn; Porkka-Heiskanen, Tarja; Virkkunen, Matti
Source: European Psychiatry. Vol 19(7), Nov 2004, pp. 433-437
ISSN: 0924-9338

Neurological soft signs (NSS) are characterized by abnormalities in motor, sensory, and integrative functions. NSS have been regarded as a result of neurodevelopmental dysfunction, and as evidence of a central nervous system defect, resulting in considerable sociopsychological dysfunction. During the last decade there has been growing evidence of brain dysfunction in severe aggressive behavior. As a symptom, aggression overlaps a number of psychiatric disorders, but it is commonly associated with antisocial personality disorder. The aim of the present study was to examine NSS in an adult criminal population using the scale by Rossi et al. 29; see record 1991-15500-001. Subjects comprised 14 homicidal men with antisocial personality disorder recruited from a forensic psychiatric examination. Ten age- and gender-matched healthy volunteers as well as eight patients with schizophrenia, but no history of physical aggression, served as controls. The NSS scores of antisocial offenders were significantly increased compared with those of the healthy controls, whereas no significant differences were observed between the scores of offenders and those of patients with schizophrenia. It can be speculated that NSS indicate a nonspecific vulnerability factor in several psychiatric syndromes, which are further influenced by a variety of genetic and environmental components. One of these syndromes may be antisocial personality disorder with severe aggression.
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