Serotonin transporter promoter polymorphism genotype is associated with temperament, personality traits and illegal drugs use among adolescents

Serotonin transporter promoter polymorphism (5-HTTLPR) genotype was previously found associated with substance use disorders, particularly in the subjects with comorbid antisocial behavior, and with temperament and personality traits at risk for substance abuse. Aim of the present study was to evaluate the possible association between 5-HTTLPR genotype and the availability to experiment illegal drugs among adolescents, in relationship with psychological characteristics. 216 caucasian high school students (aged 14-19 ys), 125 abstinent subjects, who have never experimented psychotropic drugs, and 91 experimenters of illegal drugs have been genotyped. Aggressiveness levels and temperamental traits were measured in both abstinent subjects and experimenters utilizing respectively Buss-Durkee-Hostility-Inventory (BDHI) and Cloninger Three-dimensional Personality Questionnaire (TPQ). Data about school performance have been also collected. The short-short (SS) genotype frequency was significantly higher among experimenters compared with abstinent subjects (p = 0.001). The odds ratio for the SS genotype vs the long-long (LL) genotype frequency was 4.67, 95% Cl (1.97-11.04), when experimenters were compared with abstinent students. The SS genotype frequency was significantly higher among aggressive/novelty seeker (NS) experimenters with poor school achievements, compared with drugs experimenters without aggressiveness and school failure (p = 0.02). When evaluated on the entire sample, BDHI mean total scores, NS scores at TPQ and school failure frequency were significantly higher in SS individuals, in comparison with LL subjects. Our data suggest that a decreased expression of the gene encoding the 5-HTT transporter, due to "S" promoter polymorphism, may be associated with an increased availability to experiment illegal drugs among adolescents, particularly in the subjects with more consistent aggressiveness, NS temperament and learning disabilities.