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Kirkpatrick RM, Neale MC. Applying Multivariate Discrete Distributions to Genetically Informative Count Data. Behav Genet 2015; 46:252-68. [PMID: 26497008 DOI: 10.1007/s10519-015-9757-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 10/06/2015] [Indexed: 11/26/2022]
Abstract
We present a novel method of conducting biometric analysis of twin data when the phenotypes are integer-valued counts, which often show an L-shaped distribution. Monte Carlo simulation is used to compare five likelihood-based approaches to modeling: our multivariate discrete method, when its distributional assumptions are correct, when they are incorrect, and three other methods in common use. With data simulated from a skewed discrete distribution, recovery of twin correlations and proportions of additive genetic and common environment variance was generally poor for the Normal, Lognormal and Ordinal models, but good for the two discrete models. Sex-separate applications to substance-use data from twins in the Minnesota Twin Family Study showed superior performance of two discrete models. The new methods are implemented using R and OpenMx and are freely available.
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Affiliation(s)
- Robert M Kirkpatrick
- Virginia Institute for Psychiatric & Behavioral Genetics, Virginia Commonwealth University, Richmond, VA, 23298-0126, USA.
| | - Michael C Neale
- Virginia Institute for Psychiatric & Behavioral Genetics, Virginia Commonwealth University, Richmond, VA, 23298-0126, USA
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Malone SM, Vaidyanathan U, Basu S, Miller MB, McGue M, Iacono WG. Heritability and molecular-genetic basis of the P3 event-related brain potential: a genome-wide association study. Psychophysiology 2015; 51:1246-58. [PMID: 25387705 DOI: 10.1111/psyp.12345] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
P3 amplitude is a candidate endophenotype for disinhibitory psychopathology, psychosis, and other disorders. The present study is a comprehensive analysis of the behavioral- and molecular-genetic basis of P3 amplitude and a P3 genetic factor score in a large community sample (N = 4,211) of adolescent twins and their parents, genotyped for 527,829 single nucleotide polymorphisms (SNPs). Biometric models indicated that as much as 65% of the variance in each measure was due to additive genes. All SNPs in aggregate accounted for approximately 40% to 50% of the heritable variance. However, analyses of individual SNPs did not yield any significant associations. Analyses of individual genes did not confirm previous associations between P3 amplitude and candidate genes but did yield a novel association with myelin expression factor 2 (MYEF2). Main effects of individual variants may be too small to be detected by GWAS without larger samples.
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Affiliation(s)
- Stephen M Malone
- Department of Psychology, University of Minnesota, Minneapolis, Minnesota, USA
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Malone SM, Burwell SJ, Vaidyanathan U, Miller MB, McGue M, Iacono WG. Heritability and molecular-genetic basis of resting EEG activity: a genome-wide association study. Psychophysiology 2015; 51:1225-45. [PMID: 25387704 DOI: 10.1111/psyp.12344] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Several EEG parameters are potential endophenotypes for different psychiatric disorders. The present study consists of a comprehensive behavioral- and molecular-genetic analysis of such parameters in a large community sample (N = 4,026) of adolescent twins and their parents, genotyped for 527,829 single nucleotide polymorphisms (SNPs). Biometric heritability estimates ranged from .49 to .85, with a median of .78. The additive effect of all SNPs (SNP heritability) varied across electrodes. Although individual SNPs were not significantly associated with EEG parameters, several genes were associated with delta power. We also obtained an association between the GABRA2 gene and beta power (p < .014), consistent with findings reported by others, although this did not survive Bonferroni correction. If EEG parameters conform to a largely polygenic model of inheritance, larger sample sizes will be required to detect individual variants reliably.
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Affiliation(s)
- Stephen M Malone
- Department of Psychology, University of Minnesota, Minneapolis, Minnesota, USA
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54
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Vaidyanathan U, Isen JD, Malone SM, Miller MB, McGue M, Iacono WG. Heritability and molecular genetic basis of electrodermal activity: a genome-wide association study. Psychophysiology 2015; 51:1259-71. [PMID: 25387706 DOI: 10.1111/psyp.12346] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The molecular genetic basis of electrodermal activity (EDA) was analyzed using 527,829 single nucleotide polymorphisms (SNPs) in a large population-representative sample of twins and parents (N = 4,424) in relation to various EDA indices. Biometric analyses suggested that approximately 50% or more of variance in all EDA indices was heritable. The combined effect of all SNPs together accounted for a significant amount of variance in each index, affirming their polygenic basis and heritability. However, none of the SNPs were genome-wide significant for any EDA index. Previously reported SNP associations with disorders such as substance dependence or schizophrenia, which have been linked to EDA abnormalities, were not significant; nor were associations between EDA and genes in specific neurotransmitter systems. These results suggest that EDA is influenced by multiple genes rather than by polymorphisms with large effects.
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Affiliation(s)
- Uma Vaidyanathan
- Department of Psychology, University of Minnesota, Minneapolis, Minnesota, USA
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55
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Blonigen DM, Durbin CE, Hicks BM, Johnson W, McGue M, Iacono WG. Alcohol use initiation is associated with changes in personality trait trajectories from early adolescence to young adulthood. Alcohol Clin Exp Res 2015; 39:2163-70. [PMID: 26419887 DOI: 10.1111/acer.12878] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 08/11/2015] [Indexed: 11/28/2022]
Abstract
BACKGROUND Recent work has demonstrated the codevelopment of personality traits and alcohol use characteristics from early adolescence to young adulthood. Few studies, however, have tested whether alcohol use initiation impacts trajectories of personality over this time period. We examined the effect of alcohol use initiation on personality development from early adolescence to young adulthood. METHODS Participants were male (nmen = 2,350) and female (nwomen = 2,618) twins and adoptees from 3 community-based longitudinal studies conducted at the Minnesota Center for Twin and Family Research. Data on personality traits of Positive Emotionality (PEM; Well-being), Negative Emotionality (NEM; Stress Reaction, Alienation, and Aggression), and Constraint (CON; Control and Harm Avoidance)-assessed via the Multidimensional Personality Questionnaire (MPQ)-and age of first drink were collected for up to 4 waves spanning ages 10 to 32. RESULTS Alcohol use initiation was associated with significant decreases in levels of Well-being and CON traits, most notably Control; and significant increases in levels of all NEM traits, particularly Aggression. In general, the effects of alcohol use initiation on personality traits were moderated by gender and enhanced among those with earlier age of first drink. CONCLUSIONS From early adolescence to young adulthood, alcohol use initiation predicts deviations from normative patterns of personality maturation. Such findings offer a potential mechanism underlying the codevelopment of personality traits and alcohol use characteristics during this formative period of development.
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Affiliation(s)
- Daniel M Blonigen
- Center for Innovation to Implementation, Veterans Affairs Palo Alto Health Care System, Menlo Park, California
| | - C Emily Durbin
- Department of Psychology, Michigan State University, East Lansing, Michigan
| | - Brian M Hicks
- Department of Psychiatry, University of Michigan, Ann Arbor, Michigan
| | - Wendy Johnson
- Department of Psychology, University of Edinburgh, Edinburgh, United Kingdom
| | - Matt McGue
- Department of Psychology, University of Minnesota, Minneapolis, Minnesota
| | - William G Iacono
- Department of Psychology, University of Minnesota, Minneapolis, Minnesota
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Durbin CE, Hicks BM, Blonigen DM, Johnson W, Iacono WG, McGue M. Personality trait change across late childhood to young adulthood: Evidence for nonlinearity and sex differences in change. EUROPEAN JOURNAL OF PERSONALITY 2015; 30:31-44. [PMID: 26997753 DOI: 10.1002/per.2013] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We explored patterns of self-reported personality trait change across late childhood through young adulthood in a sample assessed up to 4 times on the lower-order facets of Positive Emotionality (PEM), Negative Emotionality (NEM), and Constraint (CON). Multilevel modeling analyses were used to describe both group- and individual-level change trajectories across this time span. There was evidence for nonlinear age-related change in most traits, and substantial individual differences in change for all traits. Gender differences were detected in the change trajectories for several facets of NEM and CON. Findings add to the literature on personality development by demonstrating robust nonlinear change in several traits across late childhood to young adulthood, as well as deviations from normative patterns of maturation at the earliest ages.
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Isen JD, McGue MK, Iacono WG. Aggressive-antisocial boys develop into physically strong young men. Psychol Sci 2015; 26:444-55. [PMID: 25717041 DOI: 10.1177/0956797614567718] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 12/17/2014] [Indexed: 11/15/2022] Open
Abstract
Young men with superior upper-body strength typically show a greater proclivity for physical aggression than their weaker male counterparts. The traditional interpretation of this phenomenon is that young men calibrate their attitudes and behaviors to their physical formidability. Physical strength is thus viewed as a causal antecedent of aggressive behavior. The present study is the first to examine this phenomenon within a developmental framework. We capitalized on the fact that physical strength is a male secondary sex characteristic. In two longitudinal cohorts of children, we estimated adolescent change in upper-body strength using the slope parameter from a latent growth model. We found that males' antisocial tendencies temporally precede their physical formidability. Boys, but not girls, with greater antisocial tendencies in childhood attained larger increases in physical strength between the ages of 11 and 17. These results support sexual selection theory, indicating an adaptive congruence between male-typical behavioral dispositions and subsequent physical masculinization during puberty.
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Hicks BM, Johnson W, Durbin CE, Blonigen DM, Iacono WG, McGue M. Delineating selection and mediation effects among childhood personality and environmental risk factors in the development of adolescent substance abuse. JOURNAL OF ABNORMAL CHILD PSYCHOLOGY 2015; 42:845-59. [PMID: 24337735 DOI: 10.1007/s10802-013-9831-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Utilizing the large, longitudinal Minnesota Twin Family Study (N = 2510; 96 % European American ancestry), we examined the influence of several person-environment transactions on adolescent substance abuse. We focused on the two childhood personality traits found to be most predictive of substance abuse in this sample-socialization (willingness to follow rules and endorse conventional values) and boldness (social engagement and assurance, stress resilience, thrill seeking)-and the environmental variables of antisocial and prosocial peers, academic engagement, parent-child relationship quality, and stressful life events. Path analysis revealed that low socialization had a selection effect for each environmental risk factor, that is, socialization at age 11 predicted environmental risk at age 14, after controlling for the stability of the environmental variables from ages 11 to 14. Antisocial peers and academic engagement at age 14 then mediated some of the risk of low socialization on substance abuse at age 17, but the majority of risk for substance abuse was accounted for by the stability of socialization from age 11 to 14. Boldness at age 11 also increased risk for substance abuse, but did so primarily via a direct effect. The findings help to parse the nature of person-environment transactions across multiple personality traits and contextual risk factors that contribute to adolescent substance abuse.
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Affiliation(s)
- Brian M Hicks
- Department of Psychiatry, University of Michigan, 4250 Plymouth Rd, Ann Arbor, MI, 48109, USA,
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59
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Kirkpatrick RM, McGue M, Iacono WG. Replication of a gene-environment interaction Via Multimodel inference: additive-genetic variance in adolescents' general cognitive ability increases with family-of-origin socioeconomic status. Behav Genet 2014; 45:200-14. [PMID: 25539975 DOI: 10.1007/s10519-014-9698-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Accepted: 12/07/2014] [Indexed: 10/24/2022]
Abstract
The present study of general cognitive ability attempts to replicate and extend previous investigations of a biometric moderator, family-of-origin socioeconomic status (SES), in a sample of 2,494 pairs of adolescent twins, non-twin biological siblings, and adoptive siblings assessed with individually administered IQ tests. We hypothesized that SES would covary positively with additive-genetic variance and negatively with shared-environmental variance. Important potential confounds unaddressed in some past studies, such as twin-specific effects, assortative mating, and differential heritability by trait level, were found to be negligible. In our main analysis, we compared models by their sample-size corrected AIC, and base our statistical inference on model-averaged point estimates and standard errors. Additive-genetic variance increased with SES-an effect that was statistically significant and robust to model specification. We found no evidence that SES moderated shared-environmental influence. We attempt to explain the inconsistent replication record of these effects, and provide suggestions for future research.
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Affiliation(s)
- Robert M Kirkpatrick
- Department of Psychology, University of Minnesota, 75 E. River Rd, Minneapolis, MN, 55455, USA,
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60
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Isen J, McGue M, Iacono W. Genetic influences on the development of grip strength in adolescence. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2014; 154:189-200. [PMID: 24936605 DOI: 10.1002/ajpa.22492] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Enhanced physical strength is a secondary sex characteristic in males. Sexual dimorphism in physical strength far exceeds sex differences in stature or total body mass, suggesting a legacy of intense sexual selection. Upper-body strength is a particularly promising marker of intrasexual competitiveness in young men. Consequently, it is assumed that sex-influenced gene expression contributes to the development of physical strength. It is unclear, however, whether the underlying sources of individual differences in strength development are comparable across sex. We obtained three measurements of hand-grip strength (HGS) over a six-year period spanning adolescence in male and female same-sex twins (N = 2,513). Biometrical latent growth models were used to partition the HGS variance at age 11 (intercept) and its growth over time (slope) into genetic and environmental components. Results demonstrated that variance around the intercept was highly heritable in both males and females (88% and 79%, respectively). In males, variance around the slope exceeded that of the intercept, while the reverse held for females. Additive genetic effects accounted for most (80%) of the variance around the slope in males, but were of less importance in females (heritability = 28%). Absolute genetic variance around the slope was nearly nine-fold higher in males. This striking disparity suggests that the developmental processes shaping HGS growth are different between the sexes. We propose that this might account for the sex-specific pattern of associations between HGS and external measures (e.g., digit ratio and physical aggression) typically reported in the literature. Our results underscore the role of endogenous androgenic influences in the development of physical strength.
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61
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Vaidyanathan U, Malone SM, Donnelly JM, Hammer MA, Miller MB, McGue M, Iacono WG. Heritability and molecular genetic basis of antisaccade eye tracking error rate: a genome-wide association study. Psychophysiology 2014; 51:1272-84. [PMID: 25387707 PMCID: PMC4238043 DOI: 10.1111/psyp.12347] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Antisaccade deficits reflect abnormalities in executive function linked to various disorders including schizophrenia, externalizing psychopathology, and neurological conditions. We examined the genetic bases of antisaccade error in a sample of community-based twins and parents (N = 4,469). Biometric models showed that about half of the variance in the antisaccade response was due to genetic factors and half due to nonshared environmental factors. Molecular genetic analyses supported these results, showing that the heritability accounted for by common molecular genetic variants approximated biometric estimates. Genome-wide analyses revealed several SNPs as well as two genes-B3GNT7 and NCL-on Chromosome 2 associated with antisaccade error. SNPs and genes hypothesized to be associated with antisaccade error based on prior work, although generating some suggestive findings for MIR137, GRM8, and CACNG2, could not be confirmed.
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Affiliation(s)
- Uma Vaidyanathan
- Department of Psychology, University of Minnesota, Minneapolis, Minnesota, USA
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62
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Iacono WG, Malone SM, Vaidyanathan U, Vrieze SI. Genome-wide scans of genetic variants for psychophysiological endophenotypes: a methodological overview. Psychophysiology 2014; 51:1207-24. [PMID: 25387703 PMCID: PMC4231489 DOI: 10.1111/psyp.12343] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
This article provides an introductory overview of the investigative strategy employed to evaluate the genetic basis of 17 endophenotypes examined as part of a 20-year data collection effort from the Minnesota Center for Twin and Family Research. Included are characterization of the study samples, descriptive statistics for key properties of the psychophysiological measures, and rationale behind the steps taken in the molecular genetic study design. The statistical approach included (a) biometric analysis of twin and family data, (b) heritability analysis using 527,829 single nucleotide polymorphisms (SNPs), (c) genome-wide association analysis of these SNPs and 17,601 autosomal genes, (d) follow-up analyses of candidate SNPs and genes hypothesized to have an association with each endophenotype, (e) rare variant analysis of nonsynonymous SNPs in the exome, and (f) whole genome sequencing association analysis using 27 million genetic variants. These methods were used in the accompanying empirical articles comprising this special issue, Genome-Wide Scans of Genetic Variants for Psychophysiological Endophenotypes.
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Affiliation(s)
- William G Iacono
- Department of Psychology, University of Minnesota, Minneapolis, Minnesota, USA
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63
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Iacono WG, Vaidyanathan U, Vrieze SI, Malone SM. Knowns and unknowns for psychophysiological endophenotypes: integration and response to commentaries. Psychophysiology 2014; 51:1339-47. [PMID: 25387720 PMCID: PMC4231488 DOI: 10.1111/psyp.12358] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
We review and summarize seven molecular genetic studies of 17 psychophysiological endophenotypes that comprise this special issue of Psychophysiology, address criticisms raised in accompanying Perspective and Commentary pieces, and offer suggestions for future research. Endophenotypes are polygenic, and possibly influenced by rare genetic variants. Because they are not simpler genetically than clinical phenotypes, they are unlikely to assist gene discovery for psychiatric disorder. Once genetic variants for clinical phenotypes are identified, associated endophenotypes are likely to provide valuable insights into the psychological and neural mechanisms important to disorder pathology. This special issue provides a foundation for informed future steps in endophenotype genetics, including the formation of large sample consortia capable of fleshing out the many genetic variants contributing to individual differences in psychophysiological measures.
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Affiliation(s)
- William G Iacono
- Department of Psychology, University of Minnesota, Minneapolis, Minnesota, USA
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64
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Vrieze SI, Malone SM, Pankratz N, Vaidyanathan U, Miller MB, Kang HM, McGue M, Abecasis G, Iacono WG. Genetic associations of nonsynonymous exonic variants with psychophysiological endophenotypes. Psychophysiology 2014; 51:1300-8. [PMID: 25387709 PMCID: PMC4231532 DOI: 10.1111/psyp.12349] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
We mapped ∼85,000 rare nonsynonymous exonic single nucleotide polymorphisms (SNPs) to 17 psychophysiological endophenotypes in 4,905 individuals, including antisaccade eye movements, resting EEG, P300 amplitude, electrodermal activity, affect-modulated startle eye blink. Nonsynonymous SNPs are predicted to directly change or disrupt proteins encoded by genes and are expected to have significant biological consequences. Most such variants are rare, and new technologies can efficiently assay them on a large scale. We assayed 247,870 mostly rare SNPs on an Illumina exome array. Approximately 85,000 of the SNPs were polymorphic, rare (MAF < .05), and nonsynonymous. Single variant association tests identified a SNP in the PARD3 gene associated with theta resting EEG power. The sequence kernel association test, a gene-based test, identified a gene PNPLA7 associated with pleasant difference startle, the difference in startle magnitude between pleasant and neutral images. No other single nonsynonymous variant, or gene-based group of variants, was strongly associated with any endophenotype.
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Affiliation(s)
- Scott I. Vrieze
- Department of Biostatistics, University of Michigan, Ann Arbor, Michigan, USA
| | - Stephen M. Malone
- Department of Psychology, University of Minnesota, Minneapolis, Minnesota, USA
| | - Nathan Pankratz
- Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, Minnesota, USA
| | - Uma Vaidyanathan
- Department of Psychology, University of Minnesota, Minneapolis, Minnesota, USA
| | - Michael B. Miller
- Department of Psychology, University of Minnesota, Minneapolis, Minnesota, USA
| | - Hyun Min Kang
- Department of Biostatistics, University of Michigan, Ann Arbor, Michigan, USA
| | - Matt McGue
- Department of Psychology, University of Minnesota, Minneapolis, Minnesota, USA
| | - Gonçalo Abecasis
- Department of Biostatistics, University of Michigan, Ann Arbor, Michigan, USA
| | - William G. Iacono
- Department of Psychology, University of Minnesota, Minneapolis, Minnesota, USA
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Results of a "GWAS plus:" general cognitive ability is substantially heritable and massively polygenic. PLoS One 2014; 9:e112390. [PMID: 25383866 PMCID: PMC4226546 DOI: 10.1371/journal.pone.0112390] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Accepted: 05/04/2014] [Indexed: 11/24/2022] Open
Abstract
We carried out a genome-wide association study (GWAS) for general cognitive ability (GCA) plus three other analyses of GWAS data that aggregate the effects of multiple single-nucleotide polymorphisms (SNPs) in various ways. Our multigenerational sample comprised 7,100 Caucasian participants, drawn from two longitudinal family studies, who had been assessed with an age-appropriate IQ test and had provided DNA samples passing quality screens. We conducted the GWAS across ∼2.5 million SNPs (both typed and imputed), using a generalized least-squares method appropriate for the different family structures present in our sample, and subsequently conducted gene-based association tests. We also conducted polygenic prediction analyses under five-fold cross-validation, using two different schemes of weighting SNPs. Using parametric bootstrapping, we assessed the performance of this prediction procedure under the null. Finally, we estimated the proportion of variance attributable to all genotyped SNPs as random effects with software GCTA. The study is limited chiefly by its power to detect realistic single-SNP or single-gene effects, none of which reached genome-wide significance, though some genomic inflation was evident from the GWAS. Unit SNP weights performed about as well as least-squares regression weights under cross-validation, but the performance of both increased as more SNPs were included in calculating the polygenic score. Estimates from GCTA were 35% of phenotypic variance at the recommended biological-relatedness ceiling. Taken together, our results concur with other recent studies: they support a substantial heritability of GCA, arising from a very large number of causal SNPs, each of very small effect. We place our study in the context of the literature–both contemporary and historical–and provide accessible explication of our statistical methods.
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66
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Isen JD, Sparks JC, Iacono WG. Predictive validity of delay discounting behavior in adolescence: a longitudinal twin study. Exp Clin Psychopharmacol 2014; 22:434-43. [PMID: 24999868 PMCID: PMC4180746 DOI: 10.1037/a0037340] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
A standard assumption in the delay discounting literature is that individuals who exhibit steeper discounting of hypothetical rewards also experience greater difficulty deferring gratification to real-world rewards. There is ample cross-sectional evidence that delay discounting paradigms reflect a variety of maladaptive psychosocial outcomes, including substance use pathology. We sought to determine whether a computerized assessment of hypothetical delay discounting (HDD) taps into behavioral impulsivity in a community sample of adolescent twins (N = 675). Using a longitudinal design, we hypothesized that greater HDD at age 14-15 predicts real-world impulsive choices and risk for substance use disorders in late adolescence. We also examined the genetic and environmental structure of HDD performance. Individual differences in HDD behavior showed moderate heritability, and were prospectively associated with real-world temporal discounting at age 17-18. Contrary to expectations, HDD was not consistently related to substance use or trait impulsivity. Although a significant association between HDD behavior and past substance use emerged in males, this effect was mediated by cognitive ability. In both sexes, HDD failed to predict a comprehensive index of substance use problems and behavioral disinhibition in late adolescence. In sum, we present some of the first evidence that HDD performance is heritable and predictive of real-world temporal discounting of rewards. Nevertheless, HDD might not serve as a valid marker of substance use disorder risk in younger adolescents, particularly females.
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67
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Malone SM, Luciana M, Wilson S, Sparks JC, Hunt RH, Thomas KM, Iacono WG. Adolescent drinking and motivated decision-making: a cotwin-control investigation with monozygotic twins. Behav Genet 2014; 44:407-18. [PMID: 24676464 PMCID: PMC4058380 DOI: 10.1007/s10519-014-9651-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Accepted: 03/07/2014] [Indexed: 10/25/2022]
Abstract
The present study used a monozygotic (MZ) cotwin-control (CTC) design to investigate associations between alcohol use and performance on the Iowa gambling task (IGT) in a sample of 96 adolescents (half female). The MZ CTC design is well suited to shed light on whether poor decision-making, as reflected on IGT performance, predisposes individuals to abuse substances or is a consequence of use. Participants completed structural MRI scans as well, from which we derived gray matter volumes for cortical and subcortical regions involved in IGT performance and reduced in adolescents with problematic alcohol use. Drinking was associated with poorer task performance and with reduced volume of the left lateral orbital-frontal cortex. CTC analyses indicated that the former was due to differences between members of twin pairs in alcohol use (suggesting a causal effect of alcohol), whereas the latter was due to factors shared by twins (consistent with a pre-existing vulnerability for use). Although these preliminary findings warrant replication, they suggest that normative levels of alcohol use may diminish the quality of adolescent decision-making and thus have potentially important public health implications.
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Affiliation(s)
- Stephen M Malone
- Department of Psychology, University of Minnesota - Twin Cities, Minneapolis, MN, 55455, USA,
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68
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McLoughlin G, Makeig S, Tsuang MT. In search of biomarkers in psychiatry: EEG-based measures of brain function. Am J Med Genet B Neuropsychiatr Genet 2014; 165B:111-21. [PMID: 24273134 DOI: 10.1002/ajmg.b.32208] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Accepted: 09/12/2013] [Indexed: 11/09/2022]
Abstract
Current clinical parameters used for diagnosis and phenotypic definitions of psychopathology are both highly variable and subjective. Intensive research efforts for specific and sensitive biological markers, or biomarkers, for psychopathology as objective alternatives to the current paradigm are ongoing. While biomarker research in psychiatry has focused largely on functional neuroimaging methods for identifying the neural functions that associate with psychopathology, scalp electroencephalography (EEG) has been viewed, historically, as offering little specific brain source information, as scalp appearance is only loosely correlated to its brain source dynamics. However, ongoing advances in signal processing of EEG data can now deliver functional EEG brain-imaging with distinctly improved spatial, as well as fine temporal, resolution. One computational approach proving particularly useful for EEG cortical brain imaging is independent component analysis (ICA). ICA decomposition can be used to identify distinct cortical source activities that are sensitive and specific to the pathophysiology of psychiatric disorders. Given its practical research advantages, relatively low cost, and ease of use, EEG-imaging is now both feasible and attractive, in particular for studies involving the large samples required by genetically informative designs to characterize causal pathways to psychopathology. The completely non-invasive nature of EEG data acquisition, coupled with ongoing advances in dry, wireless, and wearable EEG technology, makes EEG-imaging increasingly attractive and appropriate for psychiatric research, including the study of developmentally young samples. Applied to large genetically and developmentally informative samples, EEG imaging can advance the search for robust diagnostic biomarkers and phenotypes in psychiatry.
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Affiliation(s)
- Gráinne McLoughlin
- Swartz Center for Computational Neuroscience, Institute for Neural Computation, University of California San Diego, La Jolla, California; Department of Psychiatry, Center for Behavioral Genomics, Institute for Genomic Medicine University of California San Diego, La Jolla, California; MRC Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, King's College London, London, UK
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69
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The effect of paternal age on offspring intelligence and personality when controlling for paternal trait level. PLoS One 2014; 9:e90097. [PMID: 24587224 PMCID: PMC3934965 DOI: 10.1371/journal.pone.0090097] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Accepted: 01/28/2014] [Indexed: 12/02/2022] Open
Abstract
Paternal age at conception has been found to predict the number of new genetic mutations. We examined the effect of father’s age at birth on offspring intelligence, head circumference and personality traits. Using the Minnesota Twin Family Study sample we tested paternal age effects while controlling for parents’ trait levels measured with the same precision as offspring’s. From evolutionary genetic considerations we predicted a negative effect of paternal age on offspring intelligence, but not on other traits. Controlling for parental intelligence (IQ) had the effect of turning an initially positive association non-significantly negative. We found paternal age effects on offspring IQ and Multidimensional Personality Questionnaire Absorption, but they were not robustly significant, nor replicable with additional covariates. No other noteworthy effects were found. Parents’ intelligence and personality correlated with their ages at twin birth, which may have obscured a small negative effect of advanced paternal age (<1% of variance explained) on intelligence. We discuss future avenues for studies of paternal age effects and suggest that stronger research designs are needed to rule out confounding factors involving birth order and the Flynn effect.
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70
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Preference on cash-choice task predicts externalizing outcomes in 17-year-olds. Behav Genet 2014; 44:102-12. [PMID: 24442381 DOI: 10.1007/s10519-013-9638-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 12/23/2013] [Indexed: 10/25/2022]
Abstract
Delay-discounting, the tendency to prefer a smaller-sooner reward to a larger-later reward, has been associated with a range of externalizing behaviors. Laboratory delay-discounting tasks have emerged as a useful measure to index impulsivity and a proclivity towards externalizing pyschopathology. While many studies demonstrate the existence of a latent externalizing factor that is heritable, there have been few genetic studies of delay-discounting. Further, the increased vulnerability for risky behavior in adolescence makes adolescent samples an attractive target for future research, and expeditious, ecologically-valid delay-discounting measures are helpful in this regard. The primary goal of this study was to help validate the utility of a "cash-choice" measure for use in a sample of older adolescents. We used a sample of 17-year-old twins (n = 791) from the Minnesota Twin Family Enrichment study. Individuals who chose the smaller-sooner reward were more likely to have used a range of addictive substances, engaged in sexual intercourse, and earned lower GPAs. Best fitting biometric models from univariate analyses supported the heritability of cash-choice and externalizing, but bivariate modeling results indicated that the correlation between cash-choice and externalizing was determined largely by shared environmental influences, thus failing to support cash-choice as a possible endophenotype for externalizing in this age group. Our findings lend further support to the utility of cash-choice as a measure of individual differences in decision making and suggest that, by late adolescence, this task indexes shared environmental risk for externalizing behavior.
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71
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Kirkpatrick RM, McGue M, Iacono WG, Miller MB, Basu S, Pankratz N. Low-Frequency Copy-Number Variants and General Cognitive Ability: No Evidence of Association. INTELLIGENCE 2014; 42:98-106. [PMID: 24497650 PMCID: PMC3909536 DOI: 10.1016/j.intell.2013.11.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Although twin, family, and adoption studies have shown that general cognitive ability (GCA) is substantially heritable, GWAS has not uncovered a genetic polymorphism replicably associated with this phenotype. However, most polymorphisms used in GWAS are common SNPs. The present study explores use of a different class of genetic variant, the copy-number variant (CNV), to predict GCA in a sample of 6,199 participants, combined from two longitudinal family studies. We aggregated low-frequency (<5%) CNV calls into eight different mutational burden scores, each reflecting a different operationalization of mutational burden. We further conducted three genome-wide association scans, each of which utilized a different subset of identified low-frequency CNVs. Association signals from the burden analyses were generally small in effect size, and none were statistically significant after a careful Type I error correction was applied. No signal from the genome-wide scans significantly differed from zero at the adjusted Type I error rate. Thus, the present study provides no evidence that CNVs underlie heritable variance in GCA, though we cannot rule out the possibility of very rare or small-effect CNVs for this trait, which would require even larger samples to detect. We interpret these null results in light of recent breakthroughs that aggregate SNP effects to explain much, but not all, of the heritable variance in some quantitative traits.
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Affiliation(s)
- Robert M. Kirkpatrick
- University of Minnesota Department of Psychology, 75 E. River Rd, Minneapolis, MN 55455
| | - Matt McGue
- University of Minnesota Department of Psychology, 75 E. River Rd, Minneapolis, MN 55455
| | - William G. Iacono
- University of Minnesota Department of Psychology, 75 E. River Rd, Minneapolis, MN 55455
| | - Michael B. Miller
- University of Minnesota Department of Psychology, 75 E. River Rd, Minneapolis, MN 55455
| | - Saonli Basu
- University of Minnesota School of Public Health, Division of Biostatistics, 420 Delaware St SE, Minneapolis, MN 55455
| | - Nathan Pankratz
- University of Minnesota Medical School, Department of Laboratory Medicine & Pathology, 420 Delaware St. SE, Minneapolis, MN 55455
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72
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The adolescent origins of substance use disorders: a behavioral genetic perspective. NEBRASKA SYMPOSIUM ON MOTIVATION. NEBRASKA SYMPOSIUM ON MOTIVATION 2014; 61:31-50. [PMID: 25306778 DOI: 10.1007/978-1-4939-0653-6_3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Over the past twenty years there has been an increasing recognition within the substance abuse research field that substance use disorders (SUDs) are usefully conceptualized within a developmental framework. That is, initiation of substance use in adolescence and escalation to substance abuse in early adulthood are strongly age-graded, with the relevant behavioral risk and protective factors manifesting early in development, often prior to substance use onset. In this chapter we review a program of research that seeks to provide a behavioral genetic perspective on the development of SUDs. The Minnesota Center for Twin and Family Research (MCTFR) undertakes longitudinal research on families including twins, adopted siblings and non-adopted siblings spanning early adolescence through early adulthood. A total of nearly 10,000 individuals in 2500 families have participated in MCTFR research. We review findings from the MCTFR to establish four general features of the development of SUDs informed by behavioral genetic research: 1) Both general and specific processes contribute to the aggregation of SUDs in families; 2) genetic contributions to SUD risk appear to be primarily at the general factor level, although the contribution of the general factor appears to decrease with age; 3) SUD risk is manifested before initiation of substance use in terms of elevated levels of externalizing psychopathology and personality characteristics indicative of low self-control; and 4) the genetic factors that contribute to SUD risk appear to be numerous with very small phenotypic effects, making them difficult to identify.
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73
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Identifying childhood characteristics that underlie premorbid risk for substance use disorders: socialization and boldness. Dev Psychopathol 2013; 26:141-57. [PMID: 24280373 DOI: 10.1017/s0954579413000862] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We utilized a longitudinal twin study (N = 2,510) to identify the child characteristics present prior to initiation of substance use that best predicted later substance use disorders. Two independent traits accounted for the majority of premorbid risk: socialization (conformity to rules and conventional values) and boldness (sociability and social assurance, stress resilience, and thrill seeking). Low socialization was associated with disruptive behavior disorders, parental externalizing disorders, and environmental adversity and exhibited moderate genetic (0.45) and shared environmental influences (0.30). Boldness was highly heritable (0.71) and associated with less internalizing distress and environmental adversity. In combination, these traits exhibited robust associations with adolescent and young adult substance use disorders (R = .48 and .50, respectively) and incremental prediction over disruptive behavior disorders, parental externalizing disorders, and environmental adversity. The results were replicated in an independent sample. Socialization and boldness offer a novel conceptualization of underlying risk for substance use disorders that has the potential to improve prediction and theory with implications for basic research, prevention, and intervention.
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74
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Gene-environment correlation in the development of adolescent substance abuse: selection effects of child personality and mediation via contextual risk factors. Dev Psychopathol 2013; 25:119-32. [PMID: 23398757 DOI: 10.1017/s0954579412000946] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We used a longitudinal twin design to examine selection effects of personality traits at age 11 on high-risk environmental contexts at age 14 and the extent to which these contexts mediated risk for substance abuse at age 17. Socialization at age 11 (willingness to follow rules and endorse conventional values) predicted exposure to contextual risk at age 14. Contextual risk partially mediated the effect of socialization on substance abuse, though socialization also had a direct effect. In contrast, boldness at age 11 (social engagement and assurance, thrill seeking, and stress resilience) also predicted substance abuse directly but was unrelated to contextual risk. There was substantial overlap in the genetic and shared environmental influences on socialization and contextual risk, and genetic risk in socialization contributed to substance abuse indirectly via increased exposure to contextual risk. This suggests that active gene-environment correlations related to individual differences in socialization contributed to an early, high-risk developmental trajectory for adolescent substance abuse. In contrast, boldness appeared to index an independent and direct genetic risk factor for adolescent substance abuse.
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75
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Bornovalova MA, Blazei R, Malone SH, McGue M, Iacono WG. Disentangling the relative contribution of parental antisociality and family discord to child disruptive disorders. Personal Disord 2013; 4:239-46. [PMID: 22888991 PMCID: PMC3499649 DOI: 10.1037/a0028607] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
A number of familial risk factors for childhood disruptive disorders have been identified. However, many of these risk factors often co-occur with parental antisociality, which by itself may account for both the familial risk factors and the increased likelihood of offspring disruptive behavior disorders (DBDs). The current study aimed to examine the association of parenting behaviors, marital conflict, and divorce with child DBDs while accounting for (a) coparent parenting behaviors, and (b) parental adult antisocial behavior (AAB). A series of regressions tested the association between family-level variables (namely, parent-child relationship quality, parental willingness to use physical punishment, marital adjustment, and history of divorce) and DBDs (attention deficit hyperactivity disorder, conduct disorder, and oppositional defiant disorder) alone and after statistically adjusting for coparent variables and parental AAB. Results indicated that parents with AAB were more likely to engage in various forms of maladaptive parenting, to divorce, and to have conflictual marriages. Maladaptive parenting, marital conflict, and divorce were associated with heightened rates of child DBDs, and these associations persisted after adjusting for coparent parenting and parental AAB. Finally, the mother's parenting behaviors had a higher impact on child DBDs than the father's parenting behaviors. Thus, familial variables continue to have an effect on childhood DBDs even after accounting for confounding influences. These variables should be a focus of research on etiology and intervention.
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Affiliation(s)
- Marina A Bornovalova
- Department of Psychology , University of South Florida, 4202 East Fowler Avenue, Tampa, FL 33620, USA.
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76
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The Minnesota Center for Twin and Family Research genome-wide association study. Twin Res Hum Genet 2013; 15:767-74. [PMID: 23363460 DOI: 10.1017/thg.2012.62] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
As part of the Genes, Environment and Development Initiative, the Minnesota Center for Twin and Family Research (MCTFR) undertook a genome-wide association study, which we describe here. A total of 8,405 research participants, clustered in four-member families, have been successfully genotyped on 527,829 single nucleotide polymorphism (SNP) markers using lllumina's Human660W-Ouad array. Quality control screening of samples and markers as well as SNP imputation procedures are described. We also describe methods for ancestry control and how the familial clustering of the MCTFR sample can be accounted for in the analysis using a Rapid Feasible Generalized Least Squares algorithm. The rich longitudinal MCTFR assessments provide numerous opportunities for collaboration.
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77
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Quantifying the Association between Personality Similarity and Marital Adjustment Using Profile Correlations: A Cautionary Tale. JOURNAL OF RESEARCH IN PERSONALITY 2013; 47:97-106. [PMID: 23459440 DOI: 10.1016/j.jrp.2012.09.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Profile correlations are sometimes used to quantify personality trait similarity between relationship partners. These coefficients are then used to test whether similar couples are happier couples. The current paper describes several different methods of calculating profile correlations and outlines procedures for testing whether these coefficients are related to marital adjustment in a sample of 1,643 couples. There was little evidence that profile correlations were related to marital adjustment after accounting for normativeness (i.e., the degree to which individual's matched the typical personality profile) and when accounting for each individual's personality attributes. Results suggest that researchers using profile correlations should be cautious given that the interpretation and psychological meaning of results often depend on how the coefficients are calculated.
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78
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Bornovalova MA, Huibregtse BM, Hicks BM, Keyes M, McGue M, Iacono W. Tests of a direct effect of childhood abuse on adult borderline personality disorder traits: a longitudinal discordant twin design. JOURNAL OF ABNORMAL PSYCHOLOGY 2013; 122:180-94. [PMID: 22686871 PMCID: PMC3482426 DOI: 10.1037/a0028328] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We used a longitudinal twin design to examine the causal association between sexual, emotional, and physical abuse in childhood (before age 18) and borderline personality disorder (BPD) traits at age 24 using a discordant twin design and biometric modeling. Additionally, we examined the mediating and moderating effects of symptoms of childhood externalizing and internalizing disorders on the link between childhood abuse and BPD traits. Although childhood abuse, BPD traits, and internalizing and externalizing symptoms were all correlated, the discordant twin analyses and biometric modeling showed little to no evidence that was consistent with a causal effect of childhood abuse on BPD traits. Instead, our results indicate that the association between childhood abuse and BPD traits stems from common genetic influences that, in some cases, also overlap with internalizing and externalizing disorders. These findings are inconsistent with the widely held assumption that childhood abuse causes BPD, and they suggest that BPD traits in adulthood are better accounted for by heritable vulnerabilities to internalizing and externalizing disorders.
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79
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Hicks BM, Iacono WG, McGue M. Index of the transmissible common liability to addiction: heritability and prospective associations with substance abuse and related outcomes. Drug Alcohol Depend 2012; 123 Suppl 1:S18-23. [PMID: 22245078 PMCID: PMC3330176 DOI: 10.1016/j.drugalcdep.2011.12.017] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Revised: 11/19/2011] [Accepted: 12/05/2011] [Indexed: 11/18/2022]
Abstract
BACKGROUND Substance use disorders (SUDs) are highly comorbid and exhibit a relatively late onset. As such, many behaviors and personality traits present prior to the initiation of substance use can be used to predict later SUDs. The transmissible liability index (TLI) is a quantitative measure of such behaviors that indexes the common liability to SUDs. We examined the predictive utility and heritability of the TLI in a large community twin sample. METHODS Using the Minnesota Twin Family Study (N=2510), we estimated TLI scores from mother, child, and teacher reports of symptom and personality measures assessed at age 11. We then estimated the genetic and environmental contributions to the association between TLI scores at age 11 and composite measures of substance abuse and behavioral disinhibition (antisocial behavior) at age 17. RESULTS For both male and female twins, TLI scores were highly heritable (.76) and exhibited moderate associations with adolescent substance abuse (r=.29) and behavioral disinhibition (r=.40). Genetic factors accounted for the association between TLI scores and the adolescent outcomes. CONCLUSIONS Findings support the utility of the TLI as a measure of the inherited, common liability to SUDs.
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Affiliation(s)
- Brian M Hicks
- Department of Psychiatry, University of Michigan, 4250 Plymouth Rd, Ann Arbor, MI 48109, USA.
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80
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Bornovalova MA, Hicks BM, Iacono WG, McGue M. Longitudinal twin study of borderline personality disorder traits and substance use in adolescence: developmental change, reciprocal effects, and genetic and environmental influences. Personal Disord 2012; 4:23-32. [PMID: 22642461 DOI: 10.1037/a0027178] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Although the comorbidity between borderline personality disorder (BPD) and substance abuse is well established, there are few longitudinal studies that have examined its developmental origins or whether the comorbidity is due to common genetic or environmental risk factors. To fill this gap, we used a large sample of female adolescent twins (N = 1,280) to examine the developmental course, reciprocal influences, and the genetic and environmental factors underlying the co-occurrence of BPD traits and substance use from age 14 to 18. Rank-order stability was moderate to high for both BPD traits (r = .58) and substance use (r = .51), whereas mean levels of substance use increased substantially from age 14 to 18 (d = 0.77) and BPD traits showed a small decline (d = -0.21). BPD traits and substance use exhibited concurrent and prospective associations; however, the longitudinal associations dropped to nonsignificance after accounting for the temporal stability of each trait. Twin analyses revealed that shared environmental factors accounted for the association between BPD traits and substance use at age 14, but genetic factors accounted for the association at age 18. These results indicate that, at least in adolescence, the comorbidity between BPD traits and substance use is a consequence of common risk factors rather than due to one being a casual antecedent of the other.
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81
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Human aggression across the lifespan: genetic propensities and environmental moderators. ADVANCES IN GENETICS 2012; 75:171-214. [PMID: 22078481 DOI: 10.1016/b978-0-12-380858-5.00007-1] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
This chapter reviews the recent evidence of genetic and environmental influences on human aggression. Findings from a large selection of the twin and adoption studies that have investigated the genetic and environmental architecture of aggressive behavior are summarized. These studies together show that about half (50%) of the variance in aggressive behavior is explained by genetic influences in both males and females, with the remaining 50% of the variance being explained by environmental factors not shared by family members. Form of aggression (reactive, proactive, direct/physical, indirect/relational), method of assessment (laboratory observation, self-report, ratings by parents and teachers), and age of the subjects-all seem to be significant moderators of the magnitude of genetic and environmental influences on aggressive behavior. Neither study design (twin vs. sibling adoption design) nor sex (male vs. female) seems to impact the magnitude of the genetic and environmental influences on aggression. There is also some evidence of gene-environment interaction (G × E) from both twin/adoption studies and molecular genetic studies. Various measures of family adversity and social disadvantage have been found to moderate genetic influences on aggressive behavior. Findings from these G × E studies suggest that not all individuals will be affected to the same degree by experiences and exposures, and that genetic predispositions may have different effects depending on the environment.
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82
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South SC, Krueger RF, Iacono WG. Understanding general and specific connections between psychopathology and marital distress: a model based approach. JOURNAL OF ABNORMAL PSYCHOLOGY 2011; 120:935-47. [PMID: 21942335 DOI: 10.1037/a0025417] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Marital distress is linked to many types of mental disorders; however, no study to date has examined this link in the context of empirically based hierarchical models of psychopathology. There may be general associations between low levels of marital quality and broad groups of comorbid psychiatric disorders as well as links between marital adjustment and specific types of mental disorders. The authors examined this issue in a sample (N = 929 couples) of currently married couples from the Minnesota Twin Family Study who completed self-report measures of relationship adjustment and were also assessed for common mental disorders. Structural equation modeling indicated that (a) higher standing on latent factors of internalizing (INT) and externalizing (EXT) psychopathology was associated with lower standing on latent factors of general marital adjustment for both husbands and wives, (b) the magnitude of these effects was similar across husbands and wives, and (c) there were no residual associations between any specific mental disorder and overall relationship adjustment after controlling for the INT and EXT factors. These findings point to the utility of hierarchical models in understanding psychopathology and its correlates. Much of the link between mental disorder and marital distress operated at the level of broad spectrums of psychopathological variation (i.e., higher levels of marital distress were associated with disorder comorbidity), suggesting that the temperamental core of these spectrums contributes not only to symptoms of mental illness but to the behaviors that lead to impaired marital quality in adulthood.
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Affiliation(s)
- Susan C South
- Department of Psychological Sciences, Purdue University, West Lafayette, IN 47907, USA.
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83
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Bezdjian S, Krueger RF, Derringer J, Malone S, McGue M, Iacono WG. The structure of DSM-IV ADHD, ODD, and CD criteria in adolescent boys: a hierarchical approach. Psychiatry Res 2011; 188:411-21. [PMID: 21470694 PMCID: PMC3146630 DOI: 10.1016/j.psychres.2011.02.027] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Revised: 01/31/2011] [Accepted: 02/04/2011] [Indexed: 11/15/2022]
Abstract
Numerous studies have examined the structure of the childhood externalizing disorder symptoms of Attention Deficit Hyperactivity Disorder (ADHD), Oppositional Defiant Disorder (ODD), and Conduct Disorder (CD), both separately as well as simultaneously. The present study expanded on previous findings by implementing a multi-level hierarchical approach to investigating the component structure of ADHD, ODD, and CD criteria in 487 14-year-old boys from the Minnesota Twin Family Study (MTFS). We found support for a hierarchical conceptualization of externalizing behavior criteria in early adolescent boys by specifying how one-, two-, three-, four-, five- and six-factor models of externalizing criteria can be integrated. These results suggest that it may be more beneficial to conceptualize different levels of this hierarchy as relevant to different issues in case conceptualization and research design, from the broad level of an overall externalizing spectrum, to the level of finer-grained subtypes within specific disorders.
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Affiliation(s)
- Serena Bezdjian
- University of Southern California, Department of Psychology, 3620 S. McClintock Ave. Los Angeles, CA 90089-1061, United States.
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84
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Kirkpatrick RM, Legrand LN, Iacono WG, McGue M. A Twin and Adoption Study of Reading Achievement: Exploration of Shared-Environmental and Gene-Environment-Interaction Effects. LEARNING AND INDIVIDUAL DIFFERENCES 2011; 21:368-375. [PMID: 21743785 DOI: 10.1016/j.lindif.2011.04.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
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 = 4,886, 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 = 9,430 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.
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85
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Elkins IJ, Malone S, Keyes M, Iacono WG, McGue M. The impact of attention-deficit/hyperactivity disorder on preadolescent adjustment may be greater for girls than for boys. JOURNAL OF CLINICAL CHILD AND ADOLESCENT PSYCHOLOGY : THE OFFICIAL JOURNAL FOR THE SOCIETY OF CLINICAL CHILD AND ADOLESCENT PSYCHOLOGY, AMERICAN PSYCHOLOGICAL ASSOCIATION, DIVISION 53 2011; 40:532-45. [PMID: 21722026 PMCID: PMC3132116 DOI: 10.1080/15374416.2011.581621] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Whether gender differences exist in the impairment associated with attention-deficit/hyperactivity disorder (ADHD) is still largely unknown, because most samples have few affected girls or include only one sex. The current study evaluated whether ADHD affects adjustment differently for girls than boys in a population-based cohort of 11-year-olds (520 girls, 478 boys). Those with a DSM-IV diagnosis of ADHD (predominantly inattentive, hyperactive-impulsive, or combined) were compared to those without ADHD on teacher, parent, and child reports of academics, peer relationships, self-concept, clinical symptoms, and treatment. Although boys and girls with ADHD experienced difficulties in all areas, girls with ADHD, especially the inattentive subtype, were more negatively affected in academics and peer relationships. Inattentive girls were less popular and more likely to be bullied than girls without ADHD, whereas inattentive boys were not. The social isolation experienced by many girls with ADHD deserves greater attention.
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Affiliation(s)
- Irene J Elkins
- Department of Psychology, University of Minnesota, Twin Cities Campus, Minneapolis, MN 55455, USA.
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86
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Hicks BM, Schalet BD, Malone SM, Iacono WG, McGue M. Psychometric and genetic architecture of substance use disorder and behavioral disinhibition measures for gene association studies. Behav Genet 2010; 41:459-75. [PMID: 21153693 DOI: 10.1007/s10519-010-9417-2] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Accepted: 11/16/2010] [Indexed: 12/11/2022]
Abstract
Using large twin, family, and adoption studies conducted at the Minnesota Center for Twin and Family Research, we describe our efforts to develop measures of substance use disorder (SUD) related phenotypes for targets in genome wide association analyses. Beginning with a diverse set of relatively narrow facet-level measures, we identified 5 constructs of intermediate complexity: nicotine, alcohol consumption, alcohol dependence, illicit drug, and behavioral disinhibition. The 5 constructs were moderately correlated (mean r = .57) reflecting a general externalizing liability to substance abuse and antisocial behavior. Analyses of the twin and adoption data revealed that this general externalizing liability accounted for much of the genetic risk in each of the intermediate-level constructs, though each also exhibited significant unique genetic and environmental risk. Additional analyses revealed substantial effects for age and sex, significant shared environmental effects, and that the mechanism of these shared environmental effects operates via siblings rather than parents. Our results provide a foundation for genome wide association analyses to detect risk alleles for SUDs as well as novel insights into genetic and environmental risk for SUDs.
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Affiliation(s)
- Brian M Hicks
- Department of Psychiatry, University of Michigan, Ann Arbor, MI 48105, USA.
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