Background Studies of gene-environment (G-E) interplay in the development of psychiatric and substance use disorders are rapidly accumulating. However, few attempts have been made to integrate findings and articulate general mechanisms of G-E influence in the emergence of psychopathology. Objective Identify patterns of G-E interplay between externalizing (EXT; antisocial behavior and substance use) disorders and several environmental risk factors. Design We used quantitative genetic models to examine how genetic and environmental risk for EXT disorders changes as a function of environmental context. Setting Participants were recruited from the community and took part in a day-long assessment at a university laboratory. Participants The sample consisted of 1315 male and female twin pairs participating in the age 17 assessment of the Minnesota Twin Family Study. Main Outcome Measures Multiple measures and informants were employed to construct a composite of EXT disorders and composite measures of 6 environmental risk factors including academic achievement and engagement, antisocial and prosocial peer affiliation, mother-child and father-child relationship problems, and stressful life events. Results A significant G × E interaction was detected between each environmental risk factor and EXT such that greater environmental adversity was associated with increased genetic risk in EXT. Conclusion Our findings demonstrate that in the context of environmental adversity, genetic factors become more important in the etiology of EXT disorders. The consistency of the results further suggests a general mechanism of environmental influence on EXT disorders regardless of the specific form of the environmental risk.

Background-Newer behavior genetic methods can better elucidate gene-environment (G-E) interplay in the development of internalizing (INT) disorders (i.e., major depression and anxiety disorders). However, no study to date has conducted a comprehensive analysis examining multiple environmental risks with the purpose of delineating how general G-E mechanisms influence the development of INT disorders.

No abstract

Background A well-established body of literature demonstrates concurrent associations between personality traits and major depressive disorder (MDD), but there have been relatively fewer investigations of their dynamic interplay over time. Methods Prospective interrelationships between late adolescent personality and MDD in early adulthood were examined in a community sample of male and female twins from the Minnesota Twin Family Study (N = 1252). Participants were classified into naturally occurring MDD groups based on the timing (adolescent- versus adult-onset) and course (chronic/recurrent versus remitting) of MDD. MDD diagnoses were assessed at ages 17, 20, 24, and 29, and personality traits (Negative Emotionality [NEM], Positive Emotionality [PEM], Constraint [CON]) were assessed at ages 17, 24, and 29. Results Multilevel modeling analyses indicated that higher age-17 NEM was associated with the subsequent development of MDD, and any MDD, regardless of onset or course, was associated with higher NEM through age 29. Moreover, the chronic/recurrent MDD groups failed to show the normative decrease in NEM from late adolescence to early adulthood. Lower age-17 PEM was also associated with the subsequent development of MDD, but only among the chronic/recurrent MDD groups. Finally, the adolescent-onset MDD groups reported lower age-17 CON relative to the never depressed and adult-onset MDD groups. Conclusions Taken together, results speak to the role of personality traits for conferring risk for the onset of MDD in late adolescence and early adulthood, as well as the pernicious implications of chronic/recurrent MDD, particularly when it onsets during adolescence, for adaptive personality development.