Serotonin transporter polymorphisms predict response inhibition in healthy volunteers.

Serotoninergic transmission is reliably implicated in inhibitory control processes. The aim of this study was to test the hypothesis if serotonin transporter polymorphisms mediate inhibitory control in healthy people. 141 healthy subjects, carefully screened for previous and current psychopathology, were genotyped for the 5-HTTLPR and rs25531 polymorphisms. Inhibitory control was ascertained with the Stop Signal Task (SST) from the Cambridge Neuropsychological Test Automated Battery (CANTAB). The triallelic gene model, reclassified and presented in a biallelic functional model, revealed a dose-dependent gene effect on SST performance with Individuals carrying the low expressive allele had inferior inhibitory control compared to high expressive carriers. This directly implicates serotonin transporter polymorphisms (5-HTTLPR plus rs25531) in response inhibition in healthy subjects.