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Biomedical subjects

L Eaves

Publications and source records attributed to L Eaves.

At least 37 records · Page 2Linked to original sources
PubMed1999

Comparing the biological and cultural inheritance of personality and social attitudes in the Virginia 30,000 study of twins and their relatives.

Measures of four dimensions of personality (Psychoticism, Extraversion, Neuroticism, and Lie scores) and six aspects of social attitudes (to sex, taxation, militarism, politics, religion and a general conservatism scale) were obtained by mailed questionnaire from 29,691 US subjects including adult twins (n = 14,761) their parents (n = 2360), their spouses (n = 4391), siblings (n = 3184) and adult children (n = 4800). After correction for the average effects of age, sex and source of sample, familial correlations were computed for 80 distinct biological and social relationships. The data allow for the estimation of the additive and non-additive effects of genes, assortative mating, vertical cultural inheritance and other non-parental effects of the shared environment on differences in personality and social attitudes. The interaction of genetic and environmental effects with sex may also be analyzed. Model-fitting analyses show that personality and social attitude measures differ markedly in major features of family resemblance. Additive and dominant genetic effects contribute to differences in both personality and attitudes, but the effects of the family environment, including vertical cultural transmission from parent to child, are much more marked for social attitudes than for personality. There is substantial assortative mating for social attitudes and almost none for personality. The causes of family resemblance depend significantly on sex for almost every variable studied. These findings clarify and extend the more tentative findings derived from previous twin, family and adoption studies.

Adult↗
PubMed1998

Co-occurrence of abuse of different drugs in men: the role of drug-specific and shared vulnerabilities.

BACKGROUND: Previous research has demonstrated genetic and environmental influences on abuse of individual substances, but there is less known about how these factors may influence the co-occurrence of abuse of different illicit drugs. METHODS: We studied 3372 male twin pairs from the Vietnam Era Twin Registry. They were interviewed using the Diagnostic Interview Schedule, Version III, Revised to investigate the extent to which the abuse of different categories of drugs occurs together within an individual, as well as the possibility that genetic and environmental factors are responsible for observed co-occurrence. Co-occurrence was quantified using odds ratios and conditional probabilities. Multivariate biometrical modeling analyses were used to assess genetic and environmental influences on co-occurrence. RESULTS: Abusing any category of drug was associated with a marked increase in the probability of abusing every other category of drugs. We found evidence for a shared or common vulnerability factor that underlies the abuse of marijuana, sedatives, stimulants, heroin or opiates, and psychedelics. This shared vulnerability is influenced by genetic, family environmental, and nonfamily environmental factors, but not every drug is influenced to the same extent by the shared vulnerability factor. Marijuana, more than other drugs, was influenced by family environmental factors. Each category of drug, except psychedelics, had genetic influences unique to itself (ie, not shared with other drug categories). Heroin had larger genetic influences unique to itself than did any other drug. CONCLUSION: There are genetically and environmentally determined characteristics that comprise a shared or common vulnerability to abuse a range of illicit drugs.

Adult↗
PubMed1998

Genetic influences on childhood hyperactivity: contrast effects imply parental rating bias, not sibling interaction.

BACKGROUND: Previous twin studies of hyperactivity have supported a 'contrast effect', whereby the more hyperactive the rating of one twin, the less the rating of the other. It has not been clear whether contrast effects occur in the twins' behaviour or in the ratings made of their behaviour but the implications for hyperactivity are different under the two models. METHOD: We use hyperactivity ratings from mothers and teachers for 1644 twin pairs in the Virginia Twin Study of Adolescent Behavioral Development (VTSABD) to explore the origin of contrast effects, making use of independent teacher reports in a proportion of twins. Models were fitted separately for the two informants and jointly to ratings combined through a latent variable, using structural equation modelling. RESULTS: Models for maternal data confirm the contrast effect previously reported. Teacher ratings show a different form of bias, with both twin confusion and correlated errors representing alternative but not mutually exclusive explanations of the data. Latent variable modelling of the joint responses allowed comparison of a model in which the contrast effect was placed on maternal ratings, representing bias, versus one in which the contrast occurred in the underlying 'true' phenotype. The fit of the former model was significantly better. CONCLUSIONS: Support is provided for the notion of contrast effects as a form of rater bias in maternal hyperactivity ratings. Different bias in teacher reports highlight that no one report can be considered a gold standard. The extent to which such biases may distort information for other data sources such as sib-pair studies of concordance/discordance is discussed.

Adolescent↗
PubMed1997

Integrating nature and nurture: implications of person-environment correlations and interactions for developmental psychopathology.

The developmental interplay between nature and nurture is discussed, with particular reference to implications for research in developmental psychopathology. The general principles include individual differences in reactivity to the environment, two-way interplay between intraindividual biology and environmental influences, and the need to consider broader social contextual features. Individuals actively process their experiences; they also act on their environment to shape and select their experiences, and individual characteristics change over time. Key findings on genetic effects include their ubiquitous influence, the multifactorial origin of most psychopathology, the involvement of several genes in most mental disorders, some genetic effects operate through dimensional risk features rather than directly on disorder, some genetic effects are dependent on gene-environment correlations and interactions, and genetic effects increase with age. Key findings on environmental effects include their ubiquitous influence, the genetic mediation of some supposed environmental effects, the importance of passive gene-environment correlations, the paucity of evidence regarding environmental effects on lifetime liability to psychopathology, the lack of understanding of environmental effects on the organism, and the importance of nonshared environmental effects. Research strategies to investigate environmental risk mediation include the range of genetically sensitive designs, migration studies, secular trend investigations, studies of nonfamilial environments, and examination of intraindividual change in relation to measured environmental alterations. Proximal processes involved in person-environment interplay are discussed in relation to person-environment interactions and evocative and active person-environment correlations.

Adaptation, Psychological↗
PubMed1997

Age changes in the causes of individual differences in conservatism.

Age-related changes are analyzed in the correlation of 3416 monozygotic and 3780 dizygotic U.S. twin pairs aged between 9 and 75+ years for conservatism scores derived from a 28-item social attitude inventory. The effects of the shared environment are overwhelming in twins aged 20 years or younger. In older twins, genetic effects appear to play a larger role. A more dynamic conception of the interaction between genes and environment in the development of complex human differences is needed.

Adolescent↗
PubMed1996

Genetic influences on DSM-III-R drug abuse and dependence: a study of 3,372 twin pairs.

Research and clinical experience indicate that drug use disorders tend to run in families. The objective of this study was to distinguish between the family environment and genetic factors as the source of this observed family resemblance. Data were collected by telephone interview from members of the Vietnam Era Twin Registry, comprising male twin pairs who served in the U.S. military between 1965 and 1975. There were 3,372 pairs in which both twins participated. Drug use disorder was defined as receiving a diagnosis of drug abuse or dependence according to DSM-III-R; 10.1% of the sample had abused or been dependent on at least one illicit drug. A significant difference between concordance rates for monozygotic (26.2%) vs. dizygotic (16.5%) twins indicated a genetic influence on drug use disorder. Biometrical modeling indicated that genetic factors (34% of the variance), the environment shared by twins (28% of the variance), and the nonshared environment (38% of the variance) had significant influences of similar magnitudes on the individual's risk of developing a drug use disorder. These results support the application of molecular genetic approaches to elucidate the genetic influence on drug use disorder, as well as the potential efficacy of environmental intervention to reduce risk.

Adult↗
PubMed1996

Heterogeneity among juvenile antisocial behaviours: findings from the Virginia Twin Study of Adolescent Behavioural Development.

The examination of heterogeneity in antisocial behaviour was accomplished by applying latent class analytic methods to multivariate categorical data on 389 same-sex male twins, aged 11 to 16 from the Virginia Twin Study of Adolescent Behavioural Development (VTSABD). The data included multiple measures of oppositional and conduct disorder, attention deficit disorder, hyperactivity, impulsivity, reading disability and anxiety from mother, teacher, and child report from both questionnaire and interview (child and adult psychiatric assessment; CAPA). A latent four-class model provided a good fit to the data and yielded four phenotypically and aetiologically distinct latent classes: (1) a non-symptomatic class influenced by both additive genetic and shared environmental factors; (2) a hyperactivity-conduct disturbance class accounted for by both additive and non-additive genetic effects; (3) a 'pure' conduct disturbance class with a very strong shared environmental component; and (4) a multisymptomatic class explained entirely by the additive effect of the genes. Further characterization of these four latent classes by age of the child and parental psychiatric history is also shown.

Adolescent↗
PubMed1996

Genetic and environmental influences on the covariation between hyperactivity and conduct disturbance in juvenile twins.

Structural equation models were applied to the maternal ratings of 265 MZ and 163 DZ male-male, 347 MZ and 160 DZ female-female, and 262 male-female twin pairs, aged 8-16 years, who participated in the Virginia Twin Study of Adolescent Behavioral Development (VTSABD). Substantial additive genetic influences and contrast effects were found for hyperactivity, and additive genetic and shared environmental effects or positive comparison effects (particularly for the girls) for oppositional/ conduct disturbance. Bivariate model fitting showed that the covariation between hyperactivity and oppositional/conduct problems in both younger and older boys and girls is almost entirely attributable to genetic factors. However, whereas in the younger males and females the same set of genes explain all the variation in hyperactivity and conduct disturbance, in the older cohort at least some of the genetic effects are behavior- and gender-specific.

Adolescent↗