Lisa Legrand - Academia.edu (original) (raw)
Papers by Lisa Legrand
Obesity and depression in adolescence and beyond: reciprocal risks
International journal of obesity (2005), 2014
Obesity and major depressive disorder (MDD) are associated, but evidence about how they relate ov... more Obesity and major depressive disorder (MDD) are associated, but evidence about how they relate over time is conflicting. The goal of this study was to examine prospective associations between depression and obesity from early adolescence through early adulthood. Participants were drawn from a statewide, community-based, Minnesota sample. MDD and obesity with onsets by early adolescence (by age 14), late adolescence (between 14 and 20) and early adulthood (ages 20-24) were assessed via structured interview (depression) and study-measured height and weight. Cross-sectional results indicated that depression and obesity with onsets by early adolescence were concurrently associated, but the same was not true later in development. Prospective results indicated that depression by early adolescence predicted the onset of obesity (odds ratio (OR)=3.76, confidence interval =1.33-10.59) during late adolescence among female individuals. Obesity that developed during late adolescence predicted t...
Predicting Addiction
American Scientist, 2005
Pronóstico del alcoholismo y las toxicomanías
Mente Y Cerebro, 2005
Acceso de usuarios registrados. Acceso de usuarios registrados Usuario Contraseña. ...
The environments of adopted and non-adopted youth: evidence on range restriction from the Sibling Interaction and Behavior Study (SIBS)
Behavior Genetics, Feb 6, 2007
Previous reviews of the literature have suggested that shared environmental effects may be undere... more Previous reviews of the literature have suggested that shared environmental effects may be underestimated in adoption studies because adopted individuals are exposed to a restricted range of family environments. A sample of 409 adoptive and 208 non-adoptive families from the Sibling Interaction and Behavior Study (SIBS) was used to identify the environmental dimensions on which adoptive families show greatest restriction and to determine the effect of this restriction on estimates of the adoptive sibling correlation. Relative to non-adoptive families, adoptive families experienced a 41% reduction of variance in parent disinhibitory psychopathology and an 18% reduction of variance in socioeconomic status (SES). There was limited evidence for range restriction in exposure to bad peer models, parent depression, or family climate. However, restriction in range in parent disinhibitory psychopathology and family SES had no effect on adoptive-sibling correlations for delinquency, drug use, and IQ. These data support the use of adoption studies to obtain direct estimates of the importance of shared environmental effects on psychological development.
Behavior genetics, Jan 21, 2015
The mu1 opioid receptor gene, OPRM1, has long been a high-priority candidate for human genetic st... more The mu1 opioid receptor gene, OPRM1, has long been a high-priority candidate for human genetic studies of addiction. Because of its potential functional significance, the non-synonymous variant rs1799971 (A118G, Asn40Asp) in OPRM1 has been extensively studied, yet its role in addiction has remained unclear, with conflicting association findings. To resolve the question of what effect, if any, rs1799971 has on substance dependence risk, we conducted collaborative meta-analyses of 25 datasets with over 28,000 European-ancestry subjects. We investigated non-specific risk for "general" substance dependence, comparing cases dependent on any substance to controls who were non-dependent on all assessed substances. We also examined five specific substance dependence diagnoses: DSM-IV alcohol, opioid, cannabis,…
Searching for interactive effects in the etiology of early-onset substance use
Behavior genetics, 1999
This study sought to expand the modest literature investigating gene x environment interactions i... more This study sought to expand the modest literature investigating gene x environment interactions in the prediction of substance use. Our sample consisted of 591 male twins from the Minnesota Twin Family Study. Their relative genetic risk was estimated from their parents' substance-related diagnoses and their environmental risk from their affiliations at age 11 with social groups likely to either encourage or discourage substance use. At age 14, the boys' own substance use was assessed. We hypothesized both main effects and an interaction between our genetic- and environmental-risk variables in the prediction of substance use by this young age. We further theorized that the boys' inherited risk might take the form of temperament, specifically externalizing tendencies. Using regression analyses and biometrical modeling, we corroborated earlier research by finding evidence for a significant interactive effect in the etiology of substance use. Our results suggest that low lev...
Twin Research and Human Genetics, 2008
A lthough life events are often conceptualized as reflecting exogenous risk factors for psychopat... more A lthough life events are often conceptualized as reflecting exogenous risk factors for psychopathology, twin studies have suggested they are heritable. We undertook a mixed twin/adoption study to further explore genetic and environmental contributions to individual differences in the experience of life events. Specifically, a sample of 618 pairs of like-sex adolescent twins, 244 pairs of likesex adopted adolescent and young adult siblings, and 128 pairs of like-sex biological siblings completed a life events interview. Events were classified as independent (not likely to have been influenced by respondent's behavior), dependent (likely to have been influenced by respondent's behavior), or familial (experienced by a family member), and then summed to form three life event scales. Variance on the scales was assumed to be a function of four factors: additive genetic effects (a 2 ), shared environmental effects (c 2 ), twin-specific effects (t 2 ), and nonshared environmental effects (e 2 ). Data were analyzed using standard biometrical models. Shared environmental effects were found to be the largest contributor to variance in familial events (c 2 = .71; 95% confidence interval of .65, .76); additive genetic effects were the largest contributor to dependent events (a 2 = .45; CI = .31, .58); and nonshared environmental effects were found to be the largest contributor independent events (e 2 = .57; CI = .51, .64). A significant twin-specific effect was also found for independent life events, indicating that twins are more likely to be exposed to such events than nontwin biological siblings. Findings are discussed in terms of their implication for understanding the nature of psychosocial risk.
Pronóstico del alcoholismo y las toxicomanías El estudio de hermanos gemelos a lo largo del tiempo podría desentrañar el origen de las conductas
Acceso de usuarios registrados. Acceso de usuarios registrados Usuario Contraseña. ...
Twin Research and Human Genetics, 2009
The Enrichment Study (ES) was designed to extend the Minnesota Twin Family Study (MTFS) by oversa... more The Enrichment Study (ES) was designed to extend the Minnesota Twin Family Study (MTFS) by oversampling 11-year-old twins at especially high risk for substance use disorders by virtue of having a childhood disruptive disorder. The sample was ascertained from Minnesota birth records. To identify high-risk twins, we conducted telephone screening interviews for parent-reported symptoms of attention-deficit/hyperactivity disorder (ADHD) and conduct disorder (CD) as well as indications of academic disengagement. Twins who exceeded a predetermined threshold were invited to participate. To facilitate comparison with the previously ascertained MTFS participants, a random sample of 11-year-old twins was also recruited. As part of the ES study, 499 twin pairs, and their parents, visited the University of Minnesota where each participant completed a clinical interview, psychophysiological evaluation, and thorough assessment of environmental risk. We were highly successful in recruiting at-risk twins; 52% of the screened male twins and 41% of the screened females met criteria for a diagnosis of ADHD, CD, or oppositional defiant disorder (ODD). At the pair level, 63% of the screened pairs had at least one member with a childhood disruptive disorder. This article provides an overview of the study design and includes a review of recent findings using this sample of twins.
Psychology of Addictive Behaviors, 2012
Despite the consensus that criteria for cannabis abuse and dependence and symptoms of withdrawal ... more Despite the consensus that criteria for cannabis abuse and dependence and symptoms of withdrawal are best explained by a single latent liability, it remains unknown whether alternative models provide a better explanation of these criteria. A series of latent factor, latent class, and hybrid factor mixture models were fitted to data from 872 recent cannabis users from the Minnesota Twin Family Study who completed Diagnostic and Statistical Manual of Mental Disorders (3rd ed., revised, and 4th ed.) diagnostic criteria for cannabis abuse, dependence, and symptoms of withdrawal. Despite theoretical appeal, results did not support latent class or factor mixture modeling. Instead, symptoms of abuse, dependence, and withdrawal were better summarized by a single latent factor Cannabis Use Disorder (CUD) for male and female young adults. An almost 2-fold sex difference in item endorsement was best explained by a single mean difference on the CUD factor, indicating that young men have a greater latent liability toward expressing CUD.
An Assessment of the Individual and Collective Effects of Variants on Height Using Twins and a Developmentally Informative Study Design
PLoS Genetics, 2011
In a sample of 3,187 twins and 3,294 of their parents, we sought to investigate association of bo... more In a sample of 3,187 twins and 3,294 of their parents, we sought to investigate association of both individual variants and a genotype-based height score involving 176 of the 180 common genetic variants with adult height identified recently by the GIANT consortium. First, longitudinal observations on height spanning pre-adolescence through adulthood in the twin sample allowed us to investigate the separate effects of the previously identified SNPs on pre-pubertal height and pubertal growth spurt. We show that the effect of SNPs identified by the GIANT consortium is primarily on prepubertal height. Only one SNP, rs7759938 in LIN28B, approached a significant association with pubertal growth. Second, we show how using the twin data to control statistically for environmental variance can provide insight into the ultimate magnitude of SNP effects and consequently the genetic architecture of a phenotype. Specifically, we computed a genetic score by weighting SNPs according to their effects as assessed via meta-analysis. This weighted score accounted for 9.2% of the phenotypic variance in height, but 14.3% of the corresponding genetic variance. Longitudinal samples will be needed to understand the developmental context of common genetic variants identified through GWAS, while genetically informative designs will be helpful in accurately characterizing the extent to which these variants account for genetic, and not just phenotypic, variance.
PEDIATRICS, 2008
Prenatal alcohol exposure is associated with increased rates of externalizing behaviors; however,... more Prenatal alcohol exposure is associated with increased rates of externalizing behaviors; however, the effects of this exposure may be confounded by genetic vulnerability to disinhibitory behavior and/or the effects of cigarette smoking in pregnancy.
Learning and Individual Differences, 2011
Existing behavior-genetic research implicates substantial influence of heredity and modest influe... more Existing behavior-genetic research implicates substantial influence of heredity and modest influence of shared environment on reading achievement and reading disability. Applying DeFries-Fulker analysis to a combined sample of twins and adoptees (N = 4886, including 266 reading-disabled probands), the present study replicates prior findings of considerable heritability for both reading achievement and reading disability. A simple biometric model adequately described parent and offspring data (combined N = 9430 parents and offspring) across differing types of families present in the sample Analyses yielded a high heritability estimate (around 0.70) and a negligible shared-environmentality estimate for both reading achievement and reading disability. No evidence of gene × environment interaction was found for parental reading ability and parental educational attainment, the two moderators analyzed.
Journal of Youth and Adolescence, 2007
cence. Boys and girls were grouped by history of DSM-III-R conduct disorder (CD) and ASPD: Contro... more cence. Boys and girls were grouped by history of DSM-III-R conduct disorder (CD) and ASPD: Controls (n = 340) had neither diagnosis; CD Only (n = 77) had CD by age 17 but no ASPD through age 20; Adolescent ASPD (n = 64) had ASPD by age 17. The Adolescent ASPD group was then compared to 20 young adult men who met criteria for ASPD (ASPD group). As expected, the Adolescent ASPD group had significantly more depression and substance use disorders, a greater performance >verbal IQ discrepancy, more deviant peers, and poorer academic functioning than the CD Only group and Controls. The Adolescent ASPD and ASPD groups did not differ on most variables. Results support the construct validity of Adolescent ASPD and suggest that such a diagnosis could help identify adolescents at risk for persistent antisocial behavior.
Journal of Personality, 2009
We tested the structure and magnitude of genetic and environmental influences on the overlap amon... more We tested the structure and magnitude of genetic and environmental influences on the overlap among self-esteem, negative emotionality, and major depression symptoms in adolescent girls (N 5 706) from the Minnesota Twin Family Study. Genetic and environmental influences on all three operated via a general, heritable factor. Genetic influences explained the majority of overlap among the three constructs, as well as most of the variance in self-esteem and negative emotionality. Genetic influences on depression were more modest and largely due to genetic factors specific to depression. These findings support the theory that self-esteem, depression, and neuroticism represent aspects of a common temperamental core. The interrelations among the three constructs in mid-adolescence is consistent with their interrelations in adulthood.
A Twin Study of State and Trait Anxiety in Childhood and Adolescence
Journal of Child Psychology and Psychiatry, 1999
Little research has addressed the relative influence of genetic and environmental factors on subc... more Little research has addressed the relative influence of genetic and environmental factors on subclinical levels of anxiety in children. Of the two twin studies to date, one concluded that measures of adolescents' self-reported trait anxiety were best explained by shared environmental factors (Thapar & McGuffin, 1995), while the second determined that approximately half the variance was attributable to genetic effects (Topolski et al., 1997). The present study, using a sample of 547 twin pairs, reached conclusions similar to those of Topolski et al. Heritability was estimated at 45%. Measures of state anxiety conformed more closely to Thapar and McGuffin's findings, with environmental factors accounting for the variance.
Journal of Abnormal Psychology, 2010
Existing structural models of psychopathology need to be expanded to include additional diagnosti... more Existing structural models of psychopathology need to be expanded to include additional diagnostic constructs beyond mood, anxiety, substance use, and antisocial behavior disorders. The goal of this study was to locate eating disorders within a hierarchical structural model of psychopathology that is anchored by broad Internalizing and Externalizing factors. Participants were female adolescent twins (N = 1,434) from the Minnesota Twin Family Study. We compared the fit of four models in which eating disorders (a) defined their own diagnostic class, (b) represented a subclass within Internalizing, (c) formed a subclass within Externalizing, and (d) were allowed to cross-load on both Internalizing and Externalizing. In the best-fitting model, eating disorders formed a sub-factor within Internalizing. These findings underscore the value of developing more comprehensive empirically based models of psychopathology to increase our understanding of diverse mental disorders.
The Environments of Adopted and Non-adopted Youth: Evidence on Range Restriction From the Sibling Interaction and Behavior Study (SIBS)
Behavior Genetics, 2007
Previous reviews of the literature have suggested that shared environmental effects may be undere... more Previous reviews of the literature have suggested that shared environmental effects may be underestimated in adoption studies because adopted individuals are exposed to a restricted range of family environments. A sample of 409 adoptive and 208 non-adoptive families from the Sibling Interaction and Behavior Study (SIBS) was used to identify the environmental dimensions on which adoptive families show greatest restriction and to determine the effect of this restriction on estimates of the adoptive sibling correlation. Relative to non-adoptive families, adoptive families experienced a 41% reduction of variance in parent disinhibitory psychopathology and an 18% reduction of variance in socioeconomic status (SES). There was limited evidence for range restriction in exposure to bad peer models, parent depression, or family climate. However, restriction in range in parent disinhibitory psychopathology and family SES had no effect on adoptive-sibling correlations for delinquency, drug use, and IQ. These data support the use of adoption studies to obtain direct estimates of the importance of shared environmental effects on psychological development.
Parental Smoking and Adolescent Problem Behavior: An Adoption Study of General and Specific Effects
American Journal of Psychiatry, 2008
It is essential to understand the effect of parental smoking on offspring tobacco use. In biologi... more It is essential to understand the effect of parental smoking on offspring tobacco use. In biologically related families, parents who smoke may transmit a nonspecific genetic risk for offspring disinhibited behavior, including tobacco use. Studying adoptive families allows one to control for genetic confounding when examining the environmental effect of exposure to parental smoking. The purpose of this study was to examine the genetic and environmental contributions to the risk represented by exposure to parental smoking and to assess the specificity of that risk. Adolescents adopted in infancy were systematically ascertained from records of three private Minnesota adoption agencies; nonadopted adolescents were ascertained from Minnesota birth records. Adolescents and their rearing parents participated in all assessments in person. The main outcome measures were self-reports of behavioral deviance, substance use, and personality, as well as DSM-IV clinical assessments of childhood disruptive disorders. The data from adoptive families suggest that exposure to parental smoking represents an environmental risk for substance use in adolescent offspring. In biologically related families, the effect of exposure to parental smoking is larger and more diverse, including substance use, disruptive behavior disorders, delinquency, deviant peer affiliations, aggressive attitudes, and preference for risk taking. This study provides evidence for an environmentally mediated pathway by which parental smoking increases risk specifically for substance use in adolescent offspring. The data are also consistent with a genetically mediated pathway by which nonadoptive parents who smoke may also transmit a nonspecific genetic risk to their offspring for disinhibited behavior.
Alcoholism: Clinical and Experimental Research, 2001
Background: Although an early age at first drink has been repeatedly associated with substantiall... more Background: Although an early age at first drink has been repeatedly associated with substantially elevated rates of alcoholism, the mechanisms underlying this association remain unclear. We investigated whether the association of age at first drink (AFD) with alcoholism was more consistent with the hypothesis that the former causes the latter or the hypothesis that both are manifestations of some common vulnerability.
Obesity and depression in adolescence and beyond: reciprocal risks
International journal of obesity (2005), 2014
Obesity and major depressive disorder (MDD) are associated, but evidence about how they relate ov... more Obesity and major depressive disorder (MDD) are associated, but evidence about how they relate over time is conflicting. The goal of this study was to examine prospective associations between depression and obesity from early adolescence through early adulthood. Participants were drawn from a statewide, community-based, Minnesota sample. MDD and obesity with onsets by early adolescence (by age 14), late adolescence (between 14 and 20) and early adulthood (ages 20-24) were assessed via structured interview (depression) and study-measured height and weight. Cross-sectional results indicated that depression and obesity with onsets by early adolescence were concurrently associated, but the same was not true later in development. Prospective results indicated that depression by early adolescence predicted the onset of obesity (odds ratio (OR)=3.76, confidence interval =1.33-10.59) during late adolescence among female individuals. Obesity that developed during late adolescence predicted t...
Predicting Addiction
American Scientist, 2005
Pronóstico del alcoholismo y las toxicomanías
Mente Y Cerebro, 2005
Acceso de usuarios registrados. Acceso de usuarios registrados Usuario Contraseña. ...
The environments of adopted and non-adopted youth: evidence on range restriction from the Sibling Interaction and Behavior Study (SIBS)
Behavior Genetics, Feb 6, 2007
Previous reviews of the literature have suggested that shared environmental effects may be undere... more Previous reviews of the literature have suggested that shared environmental effects may be underestimated in adoption studies because adopted individuals are exposed to a restricted range of family environments. A sample of 409 adoptive and 208 non-adoptive families from the Sibling Interaction and Behavior Study (SIBS) was used to identify the environmental dimensions on which adoptive families show greatest restriction and to determine the effect of this restriction on estimates of the adoptive sibling correlation. Relative to non-adoptive families, adoptive families experienced a 41% reduction of variance in parent disinhibitory psychopathology and an 18% reduction of variance in socioeconomic status (SES). There was limited evidence for range restriction in exposure to bad peer models, parent depression, or family climate. However, restriction in range in parent disinhibitory psychopathology and family SES had no effect on adoptive-sibling correlations for delinquency, drug use, and IQ. These data support the use of adoption studies to obtain direct estimates of the importance of shared environmental effects on psychological development.
Behavior genetics, Jan 21, 2015
The mu1 opioid receptor gene, OPRM1, has long been a high-priority candidate for human genetic st... more The mu1 opioid receptor gene, OPRM1, has long been a high-priority candidate for human genetic studies of addiction. Because of its potential functional significance, the non-synonymous variant rs1799971 (A118G, Asn40Asp) in OPRM1 has been extensively studied, yet its role in addiction has remained unclear, with conflicting association findings. To resolve the question of what effect, if any, rs1799971 has on substance dependence risk, we conducted collaborative meta-analyses of 25 datasets with over 28,000 European-ancestry subjects. We investigated non-specific risk for "general" substance dependence, comparing cases dependent on any substance to controls who were non-dependent on all assessed substances. We also examined five specific substance dependence diagnoses: DSM-IV alcohol, opioid, cannabis,…
Searching for interactive effects in the etiology of early-onset substance use
Behavior genetics, 1999
This study sought to expand the modest literature investigating gene x environment interactions i... more This study sought to expand the modest literature investigating gene x environment interactions in the prediction of substance use. Our sample consisted of 591 male twins from the Minnesota Twin Family Study. Their relative genetic risk was estimated from their parents' substance-related diagnoses and their environmental risk from their affiliations at age 11 with social groups likely to either encourage or discourage substance use. At age 14, the boys' own substance use was assessed. We hypothesized both main effects and an interaction between our genetic- and environmental-risk variables in the prediction of substance use by this young age. We further theorized that the boys' inherited risk might take the form of temperament, specifically externalizing tendencies. Using regression analyses and biometrical modeling, we corroborated earlier research by finding evidence for a significant interactive effect in the etiology of substance use. Our results suggest that low lev...
Twin Research and Human Genetics, 2008
A lthough life events are often conceptualized as reflecting exogenous risk factors for psychopat... more A lthough life events are often conceptualized as reflecting exogenous risk factors for psychopathology, twin studies have suggested they are heritable. We undertook a mixed twin/adoption study to further explore genetic and environmental contributions to individual differences in the experience of life events. Specifically, a sample of 618 pairs of like-sex adolescent twins, 244 pairs of likesex adopted adolescent and young adult siblings, and 128 pairs of like-sex biological siblings completed a life events interview. Events were classified as independent (not likely to have been influenced by respondent's behavior), dependent (likely to have been influenced by respondent's behavior), or familial (experienced by a family member), and then summed to form three life event scales. Variance on the scales was assumed to be a function of four factors: additive genetic effects (a 2 ), shared environmental effects (c 2 ), twin-specific effects (t 2 ), and nonshared environmental effects (e 2 ). Data were analyzed using standard biometrical models. Shared environmental effects were found to be the largest contributor to variance in familial events (c 2 = .71; 95% confidence interval of .65, .76); additive genetic effects were the largest contributor to dependent events (a 2 = .45; CI = .31, .58); and nonshared environmental effects were found to be the largest contributor independent events (e 2 = .57; CI = .51, .64). A significant twin-specific effect was also found for independent life events, indicating that twins are more likely to be exposed to such events than nontwin biological siblings. Findings are discussed in terms of their implication for understanding the nature of psychosocial risk.
Pronóstico del alcoholismo y las toxicomanías El estudio de hermanos gemelos a lo largo del tiempo podría desentrañar el origen de las conductas
Acceso de usuarios registrados. Acceso de usuarios registrados Usuario Contraseña. ...
Twin Research and Human Genetics, 2009
The Enrichment Study (ES) was designed to extend the Minnesota Twin Family Study (MTFS) by oversa... more The Enrichment Study (ES) was designed to extend the Minnesota Twin Family Study (MTFS) by oversampling 11-year-old twins at especially high risk for substance use disorders by virtue of having a childhood disruptive disorder. The sample was ascertained from Minnesota birth records. To identify high-risk twins, we conducted telephone screening interviews for parent-reported symptoms of attention-deficit/hyperactivity disorder (ADHD) and conduct disorder (CD) as well as indications of academic disengagement. Twins who exceeded a predetermined threshold were invited to participate. To facilitate comparison with the previously ascertained MTFS participants, a random sample of 11-year-old twins was also recruited. As part of the ES study, 499 twin pairs, and their parents, visited the University of Minnesota where each participant completed a clinical interview, psychophysiological evaluation, and thorough assessment of environmental risk. We were highly successful in recruiting at-risk twins; 52% of the screened male twins and 41% of the screened females met criteria for a diagnosis of ADHD, CD, or oppositional defiant disorder (ODD). At the pair level, 63% of the screened pairs had at least one member with a childhood disruptive disorder. This article provides an overview of the study design and includes a review of recent findings using this sample of twins.
Psychology of Addictive Behaviors, 2012
Despite the consensus that criteria for cannabis abuse and dependence and symptoms of withdrawal ... more Despite the consensus that criteria for cannabis abuse and dependence and symptoms of withdrawal are best explained by a single latent liability, it remains unknown whether alternative models provide a better explanation of these criteria. A series of latent factor, latent class, and hybrid factor mixture models were fitted to data from 872 recent cannabis users from the Minnesota Twin Family Study who completed Diagnostic and Statistical Manual of Mental Disorders (3rd ed., revised, and 4th ed.) diagnostic criteria for cannabis abuse, dependence, and symptoms of withdrawal. Despite theoretical appeal, results did not support latent class or factor mixture modeling. Instead, symptoms of abuse, dependence, and withdrawal were better summarized by a single latent factor Cannabis Use Disorder (CUD) for male and female young adults. An almost 2-fold sex difference in item endorsement was best explained by a single mean difference on the CUD factor, indicating that young men have a greater latent liability toward expressing CUD.
An Assessment of the Individual and Collective Effects of Variants on Height Using Twins and a Developmentally Informative Study Design
PLoS Genetics, 2011
In a sample of 3,187 twins and 3,294 of their parents, we sought to investigate association of bo... more In a sample of 3,187 twins and 3,294 of their parents, we sought to investigate association of both individual variants and a genotype-based height score involving 176 of the 180 common genetic variants with adult height identified recently by the GIANT consortium. First, longitudinal observations on height spanning pre-adolescence through adulthood in the twin sample allowed us to investigate the separate effects of the previously identified SNPs on pre-pubertal height and pubertal growth spurt. We show that the effect of SNPs identified by the GIANT consortium is primarily on prepubertal height. Only one SNP, rs7759938 in LIN28B, approached a significant association with pubertal growth. Second, we show how using the twin data to control statistically for environmental variance can provide insight into the ultimate magnitude of SNP effects and consequently the genetic architecture of a phenotype. Specifically, we computed a genetic score by weighting SNPs according to their effects as assessed via meta-analysis. This weighted score accounted for 9.2% of the phenotypic variance in height, but 14.3% of the corresponding genetic variance. Longitudinal samples will be needed to understand the developmental context of common genetic variants identified through GWAS, while genetically informative designs will be helpful in accurately characterizing the extent to which these variants account for genetic, and not just phenotypic, variance.
PEDIATRICS, 2008
Prenatal alcohol exposure is associated with increased rates of externalizing behaviors; however,... more Prenatal alcohol exposure is associated with increased rates of externalizing behaviors; however, the effects of this exposure may be confounded by genetic vulnerability to disinhibitory behavior and/or the effects of cigarette smoking in pregnancy.
Learning and Individual Differences, 2011
Existing behavior-genetic research implicates substantial influence of heredity and modest influe... more Existing behavior-genetic research implicates substantial influence of heredity and modest influence of shared environment on reading achievement and reading disability. Applying DeFries-Fulker analysis to a combined sample of twins and adoptees (N = 4886, including 266 reading-disabled probands), the present study replicates prior findings of considerable heritability for both reading achievement and reading disability. A simple biometric model adequately described parent and offspring data (combined N = 9430 parents and offspring) across differing types of families present in the sample Analyses yielded a high heritability estimate (around 0.70) and a negligible shared-environmentality estimate for both reading achievement and reading disability. No evidence of gene × environment interaction was found for parental reading ability and parental educational attainment, the two moderators analyzed.
Journal of Youth and Adolescence, 2007
cence. Boys and girls were grouped by history of DSM-III-R conduct disorder (CD) and ASPD: Contro... more cence. Boys and girls were grouped by history of DSM-III-R conduct disorder (CD) and ASPD: Controls (n = 340) had neither diagnosis; CD Only (n = 77) had CD by age 17 but no ASPD through age 20; Adolescent ASPD (n = 64) had ASPD by age 17. The Adolescent ASPD group was then compared to 20 young adult men who met criteria for ASPD (ASPD group). As expected, the Adolescent ASPD group had significantly more depression and substance use disorders, a greater performance >verbal IQ discrepancy, more deviant peers, and poorer academic functioning than the CD Only group and Controls. The Adolescent ASPD and ASPD groups did not differ on most variables. Results support the construct validity of Adolescent ASPD and suggest that such a diagnosis could help identify adolescents at risk for persistent antisocial behavior.
Journal of Personality, 2009
We tested the structure and magnitude of genetic and environmental influences on the overlap amon... more We tested the structure and magnitude of genetic and environmental influences on the overlap among self-esteem, negative emotionality, and major depression symptoms in adolescent girls (N 5 706) from the Minnesota Twin Family Study. Genetic and environmental influences on all three operated via a general, heritable factor. Genetic influences explained the majority of overlap among the three constructs, as well as most of the variance in self-esteem and negative emotionality. Genetic influences on depression were more modest and largely due to genetic factors specific to depression. These findings support the theory that self-esteem, depression, and neuroticism represent aspects of a common temperamental core. The interrelations among the three constructs in mid-adolescence is consistent with their interrelations in adulthood.
A Twin Study of State and Trait Anxiety in Childhood and Adolescence
Journal of Child Psychology and Psychiatry, 1999
Little research has addressed the relative influence of genetic and environmental factors on subc... more Little research has addressed the relative influence of genetic and environmental factors on subclinical levels of anxiety in children. Of the two twin studies to date, one concluded that measures of adolescents' self-reported trait anxiety were best explained by shared environmental factors (Thapar & McGuffin, 1995), while the second determined that approximately half the variance was attributable to genetic effects (Topolski et al., 1997). The present study, using a sample of 547 twin pairs, reached conclusions similar to those of Topolski et al. Heritability was estimated at 45%. Measures of state anxiety conformed more closely to Thapar and McGuffin's findings, with environmental factors accounting for the variance.
Journal of Abnormal Psychology, 2010
Existing structural models of psychopathology need to be expanded to include additional diagnosti... more Existing structural models of psychopathology need to be expanded to include additional diagnostic constructs beyond mood, anxiety, substance use, and antisocial behavior disorders. The goal of this study was to locate eating disorders within a hierarchical structural model of psychopathology that is anchored by broad Internalizing and Externalizing factors. Participants were female adolescent twins (N = 1,434) from the Minnesota Twin Family Study. We compared the fit of four models in which eating disorders (a) defined their own diagnostic class, (b) represented a subclass within Internalizing, (c) formed a subclass within Externalizing, and (d) were allowed to cross-load on both Internalizing and Externalizing. In the best-fitting model, eating disorders formed a sub-factor within Internalizing. These findings underscore the value of developing more comprehensive empirically based models of psychopathology to increase our understanding of diverse mental disorders.
The Environments of Adopted and Non-adopted Youth: Evidence on Range Restriction From the Sibling Interaction and Behavior Study (SIBS)
Behavior Genetics, 2007
Previous reviews of the literature have suggested that shared environmental effects may be undere... more Previous reviews of the literature have suggested that shared environmental effects may be underestimated in adoption studies because adopted individuals are exposed to a restricted range of family environments. A sample of 409 adoptive and 208 non-adoptive families from the Sibling Interaction and Behavior Study (SIBS) was used to identify the environmental dimensions on which adoptive families show greatest restriction and to determine the effect of this restriction on estimates of the adoptive sibling correlation. Relative to non-adoptive families, adoptive families experienced a 41% reduction of variance in parent disinhibitory psychopathology and an 18% reduction of variance in socioeconomic status (SES). There was limited evidence for range restriction in exposure to bad peer models, parent depression, or family climate. However, restriction in range in parent disinhibitory psychopathology and family SES had no effect on adoptive-sibling correlations for delinquency, drug use, and IQ. These data support the use of adoption studies to obtain direct estimates of the importance of shared environmental effects on psychological development.
Parental Smoking and Adolescent Problem Behavior: An Adoption Study of General and Specific Effects
American Journal of Psychiatry, 2008
It is essential to understand the effect of parental smoking on offspring tobacco use. In biologi... more It is essential to understand the effect of parental smoking on offspring tobacco use. In biologically related families, parents who smoke may transmit a nonspecific genetic risk for offspring disinhibited behavior, including tobacco use. Studying adoptive families allows one to control for genetic confounding when examining the environmental effect of exposure to parental smoking. The purpose of this study was to examine the genetic and environmental contributions to the risk represented by exposure to parental smoking and to assess the specificity of that risk. Adolescents adopted in infancy were systematically ascertained from records of three private Minnesota adoption agencies; nonadopted adolescents were ascertained from Minnesota birth records. Adolescents and their rearing parents participated in all assessments in person. The main outcome measures were self-reports of behavioral deviance, substance use, and personality, as well as DSM-IV clinical assessments of childhood disruptive disorders. The data from adoptive families suggest that exposure to parental smoking represents an environmental risk for substance use in adolescent offspring. In biologically related families, the effect of exposure to parental smoking is larger and more diverse, including substance use, disruptive behavior disorders, delinquency, deviant peer affiliations, aggressive attitudes, and preference for risk taking. This study provides evidence for an environmentally mediated pathway by which parental smoking increases risk specifically for substance use in adolescent offspring. The data are also consistent with a genetically mediated pathway by which nonadoptive parents who smoke may also transmit a nonspecific genetic risk to their offspring for disinhibited behavior.
Alcoholism: Clinical and Experimental Research, 2001
Background: Although an early age at first drink has been repeatedly associated with substantiall... more Background: Although an early age at first drink has been repeatedly associated with substantially elevated rates of alcoholism, the mechanisms underlying this association remain unclear. We investigated whether the association of age at first drink (AFD) with alcoholism was more consistent with the hypothesis that the former causes the latter or the hypothesis that both are manifestations of some common vulnerability.