Authors:Seth J. Gillihan, Geena Mary V. Sankoorikal, Edward S. Brodkin and Martha J. Farah
Despite the significant associations between the short (S) allele of the serotonin transporter-linked polymorphic region (5-HTTLPR) and various psychiatric disorders, the S allele has persisted at relatively high prevalence in the human population worldwide. Based on findings of greater amygdala activity among S allele carriers both at rest and in response to threat-relevant stimuli, the S allele appears to be associated with greater vigilance for danger; therefore we hypothesized that the S allele would be associated with lower scores on risk-related traits. In order to test this hypothesis we assessed the 5-HTTLPR genotype of 81 individuals of European ancestry and tested for an effect of genotype on two dimensions of risk-related behavior: venturesomeness and impulsivity. Results revealed significantly lower venturesomeness and a trend toward lower impulsivity associated with the S allele. We speculate that relatively greater vigilance for and avoidance of danger may counteract the disease risk associated with the 5-HTTLPR S allele and contribute to its persistence at high prevalence in the human population. Replication in a larger sample is necessary in order to confirm these associations.