No abstract

Studies of the association between polymorphisms of the serotonin transporter gene (5-HTT) and trait anxiety have produced inconsistent results, raising questions about the strength of the relationship and the methodological conditions under which the relationship holds. We conducted a meta-analysis of existing studies to provide formal statistical measures of the strength of the linked polymorphic region of the serotonin transporter gene (5-HTTLPR)-anxiety relationship. For the entire collection of 26 studies, results provided no support for a relationship between anxiety and the presence of the short form of the 5-HTTLPR polymorphism. There was strong evidence of the presence of moderating variables, however, and subsequent analysis revealed that choice of the measure of trait anxiety was significant. Studies using the Neuroticism scale of Costa and McCrae were found to produce a small positive effect (d¼0.23). Other potential moderators (country of study origin, type of subject) did not have a meaningful impact on d statistics. These findings indicate that 5-HTTLPR may in fact have a small but reliable influence on personality, particularly in the manifestation of trait anxiety when measured with a neuroticism scale based on the five-factor model of personality. Our results suggest that the success of future personality genetics research will be maximized by the use of personality measures from both the psychobiological and five-factor models.

In this meta-analysis we examined Five-Factor Model of personality (FFM) characteristics of externalizing disorders. Two pathologies, Antisocial Personality Disorder (APD) and Substance Use Disorder (SUD), have significant levels of co-occurrence that may be due to shared personality traits. Results from 63 samples (N = 15,331) were analyzed in order to summarize and compare five-factor results for APD, SUD, and co-occurring APD/SUD. Shared and unique personality features were identified at both the domain and the facet level of the FFM. Moderation analyses indicated that sample source (clinical versus community) and diagnosis (psychopathy versus DSM-based APD) accounted for some of the variability at the domain level. Results are discussed with respect to personality and externalizing disorders.

Studies of the association between polymorphisms within and near the dopamine D4 receptor (DRD4) gene and novelty seeking (NS) have produced inconsistent results, raising questions about the strength of the relationship and the methodological conditions under which the relationship holds. We conducted three meta-analyses of existing studies to provide formal statistical measures of the strength of the DRD4-NS relationship. Results provided no support for a relationship between NS and the presence of the 7-repeat allele of the VNTR polymorphism. A small positive effect, however, was found for long repeats of the same polymorphism. The most promising findings were obtained for the relationship with the -521 C/T promoter polymorphism, for which the analysis showed an effect size of 0.32. The positive findings are consistent with a polygenic model of influence on fundamental personality dimensions.