Evidence for an Extended Externalizing Spectrum in Youth: Associations between Psychopathology, Personality, and Behavior Restricted; Files Only
Poore, Holly (Spring 2021)
Published
Abstract
Personality-psychopathology associations have long been documented, leading researchers to propose alternative models that seek to explain the mechanism of these associations. One such model, termed a spectrum model, posits that both constructs exist along the same continuum. Herein, I present three studies that examine evidence for an Externalizing Spectrum in youth using phenotypic (Study 1), quantitative genetic (Study 2), and molecular genetic analyses (Study 3). Studies 1 and 2 relied on a representative sample of twins and their siblings who are part of the Georgia Twin Registry (Npairs = 875, Ntotal = 2208). Study 3 relied on publicly available genome-wide association study (GWAS) summary statistics for externalizing disorders and related traits. In Study 1, we use Structural Equation Modeling and Item Response Theory to test the hypothesis that relevant personality and behavioral traits perform well as indicators of an Externalizing Spectrum model. We found evidence that traits reflecting narcissism, impulsivity, agreeableness, conscientiousness, behavioral disinhibition, and reactive, proactive, and relational aggression, load strongly with symptoms of externalizing disorders. We also found that many of these traits extend the levels of Externalizing captured, such that we were able to capture lower and higher levels of Externalizing relative to the symptom dimensions alone. In Study 2, we used quantitative genetic (i.e., twin) models to estimate the amount of etiological variance that these candidate traits share in common with Externalizing. We found that most candidate traits share substantial genetic, but not environmental, variance with externalizing symptom dimensions. Further, we found support for a model in which etiological influences on each disorder and trait predominantly exert their influence through a higher-order Externalizing factor that captures the genetic and environmental variance shared among its indicators, as well as genetic and environmental variance unique to each disorder and trait. Finally, in Study 3, we leveraged genetic correlations among externalizing disorders and related traits using GWAS summary statistics to test alternative models of the Externalizing Spectrum at the genomic level. We found support for the inclusion of aggression, agreeableness, risk tolerance, and number of sexual partners in the Externalizing spectrum. Taken together, our findings have several important implications. First, results from all studies support the existence of a broad Externalizing factor in youth that confers risk for many disorders and traits. Second, results from Studies 1 and 2 support the retention of specific facets of externalizing that represent unique variance not shared with other externalizing indicators. Finally, we found that the observed phenotypic associations between disorders and traits is due, at least in part, to shared etiological mechanisms, particularly common genetic influences. Overall, our findings support the existence of an Externalizing spectrum in youth, which should be the target of future studies examining the structure, nature, and treatment of externalizing problems in children and adolescents.
Table of Contents
Table of Contents
General Introduction 1
Study 1: Examining Phenotypic Structural Models of the Externalizing Spectrum in Youth
Abstract 13
Introduction 14
Method 21
Results 31
Discussion 41
Tables 53
Figures 63
Study 2: Etiological Covariance Between Psychopathology and Personality Traits
Abstract 90
Introduction 91
Method 95
Results 99
Discussion 102
Tables 108
Figures 114
Study 3: Examining Evidence for an Externalizing Spectrum at the Genomic Level
Abstract 119
Introduction 120
Method 122
Results 127
Discussion 129
Tables 132
Figures 137
General Discussion 151
References 159
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File download under embargo until 25 May 2027 | 2021-04-08 16:07:36 -0400 | File download under embargo until 25 May 2027 |
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