Somatic markers mediate the effect of serotonin transporter gene polymorphisms on Iowa Gambling Task.

This study investigated whether somatic markers mediate the effect of serotonin transporter genotype on Iowa Gambling Task (IGT) performance. Participants (N = 135) were genotyped for the insertion/deletion and single-nucleotide (rs25531) polymorphisms in the promoter region of the serotonin transporter gene (5-HTTLPR). The results of mediation analyses indicated that skin conductance responses that anticipated IGT card selections partially (i.e. 42% of the total effect) mediated the effect of genotype on IGT performance. In comparison with high-functioning 5-HTTLPR genotypes, the low-functioning genotypes were associated with higher total IGT scores. This suggests that the higher synaptic availability of serotonin, associated with the low-functioning 5-HTTLPR genotypes, may confer differential susceptibility to decision making under risk, and that almost half of this effect is explained by facilitated somatic markers during IGT.