The genetic and environmental structure of Cloninger's model of personality

Cloninger's trait theory is a neurobiological-based model of personality that attempts to assess genetically homogenous and independent temperament dimensions: novelty-seeking, harm-avoidance, reward-dependence and persistence. While most personality research has focused on adults or childhood temperament, very little is known about the etiological influences on personality during adolescence. This study aims to establish that Cloninger's personality constructs are heritable in adolescence. Secondly, four candidate genes in the dopaminergic and the serotonergic systems (DRD2, DRD4, DAT1, and 5-HTT), were examined in association with Cloninger's personality constructs. As Cloninger's theory is profile driven, in addition to looking at each trait independently, personality as a profile was examined in multivariate analyses of these candidate genes. Multivariate analyses were also conducted at the genotype level, in which the simultaneous effect of more than one candidate gene on personality were examined.;Participants were drawn from the Center for Antisocial Drug Dependence (CADD; PI: Thomas J. Crowley)—an ongoing, multi-component, collaborative study underway at the University of Colorado. 2524 Adolescent participants (ages 11–18) were drawn from a community sample and a clinical sample of adolescents in treatment for conduct disorder and substance use disorder.;Biometrical analyses confirmed that Cloninger's personality dimensions (except for persistence, as measured by the J-TCI and TPQ) are moderately heritable phenotypes, and not influenced by common environmental effects. Heritability ranged from 28% to 36%. No significant association was found between any of Cloninger's personality dimensions and the four candidate genes using between family association tests. However, sibling-based association results that account for population stratification showed specific genes that may play a role in these personality constructs. DRD4 was significantly associated with novelty seeking, DRD2 and 5-HTT with harm avoidance, and DAT1 with reward dependence. The contribution of polymorphisms of these genes to the phenotypic variance was small, ranging from 2.8%–4.6%. An extended multivariate sibling-based analysis found an additive simultaneous association between DRD2 and 5-HTT with harm avoidance. In summary, Cloninger's personality scales are probably influenced by multiple additional genetic factors not examined in the present study. Multivariate analyses suggest that personality is multifaceted both at a genetic level and a phenotypic level.