Harm avoidance

Abstract: Recently, there has been growing enthusiasm for exploring biological approaches to personality, especially in the area of genetic research into the identification of those genes responsible for particular personality traits. The aim of this study was to investigate the association between the serotonin transporter-linked promoter region (5-HTTLPR) polymorphism and personality traits. We recruited 211 unrelated, normal subjects. The Korean version of the Temperament and Character Inventory (TCI) was used to assess certain personality traits. From blood samples taken from the subjects, DNA was isolated using standard techniques and the 5-HTTLPR polymorphism was genotyped by means of polymerase chain reaction and electrophoresis. We classified the subject into the s/s, s/l, and l/l groups according to their genotype. The differences in the temperament factors of the TCI between group S (s/s genotype) and group L (s/l + l/l genotype) were assessed, after the inclusion of gender and age as covariates in the analysis of variance. After controlling for gender and age, there were no associations between the harm avoidance, novelty seeking, and reward dependence scores and the genotypes. However, the persistence score of group S was significantly higher than that of group L. Our results suggest that the 5-HTTLPR polymorphism may be associated with the persistence score of the TCI in a normal Korean population.

Abstract: Although the serotonin transporter length polymorphic region (5-HTTLPR) polymorphism is an extensively-investigated genetic marker of anxiety related personality traits (neuroticism and harm avoidance) and affective disorders, effect sizes in meta-analyses are small, if present at all, and all available primary studies to date lack mandatory statistical power. Moreover, questionnaire data is prone to confounding by variables such as social desirability. Therefore, extreme response style (ERS) is suggested as a new approach to elucidate the relationship between 5-HTTLPR and negative emotionality, as it is more implicit and of high reliability. N = 1075 healthy subjects were genotyped for 5-HTTLPR and a flanking polymorphism (rs25531) and filled out the NEO Five Factor Inventory and the Temperament Character Inventory. As dependent variable the number of extreme responses across all items was calculated. Using the common genotype or the triallelic approach (including rs25531) the meta-analytic findings could not be replicated. However, there was a significant association between 5-HTTLPR and extreme response style. Carriers of the L-allele or the L'-allele, respectively, had a significantly higher number of extreme responses than homozygous SS carriers across all items of the NEO Five Factor Inventory. This finding could be replicated in an alternative personality questionnaire (Affective Neuroscience Personality Scales, ANPS). There is a long tradition in psychological assessment indicating that ERS is an implicit measure of personality. Given the positive findings of the present study, ERS qualifies as a promising endophenotype in future genetic association studies on personality and affective disorders.

Abstract: Rationale: A number of studies have reported abnormalities of serotonin function in aggressive and impulsive behaviours in psychiatric and forensic populations. It is unknown whether this is because serotonin function plays a part in determining the dimension of trait impulsiveness in the general population or whether this is restricted to these behaviourally extreme groups. Method: The prolactin response to d-fenfluramine was measured in subjects scoring high and low on a scale of impulsiveness selected from a panel of healthy volunteers screened for impulsiveness. Measures included the I7 impulsiveness scale, State Trait Anger Expression Inventory (STAngXI) and the Tridimensional Personality Questionnaire (TPQ). Plasma cortisol was also determined along with fenfluramine and its metabolite norfenfluramine. Results: The high impulsive group had reduced AUC (PRL) compared with the low impulsive group; this remained significant after adjusting for baseline prolactin, cortisol and drug levels. There was no significant association between impulsiveness, the harm avoidance subscale of the TPQ or trait anger (STAngXI) and prolactin rise. Repeated serum prolactin measures were not significantly different between the two groups. Conclusions: This study provides some support to the hypothesis that reduced serotonin function contributes to high trait impulsiveness and is not restricted to behaviourally extreme populations.