Objectives: The objective of this study is to examine the influence of serotonin transporter polymorphisms on the role of the amygdala when controls and subjects with Austism process fearful faces.
Methods: 13 adults with ASD and 11 matched controls performed an event-related functional Magnetic Resonance implicit fear processing task on a GE 1.5T Signa Scanner. All participants were male, right-handed, with an IQ >70. All individuals with ASD met algorithm cut-offs for autism on the ADI or ADOS. Subjects viewed expressions of fear contrasted with a cross hair baseline condition. The BOLD signal was extracted from the left amygdala for both groups of subjects. Genotyping was performed to ascertain the allelic varation of the 5-HTT for either the short containing (SS+SL) or long (LL). Self-reporting psychiatric inventories and neuropsychological tests were performed.
Results: Genotyping revealed that the controls had 2 subjects with LL and 9 subjects with SS+SL, while the ASD group had 3 subjects with LL and 10 subjects with SS+SL. For the controls, there was a significant linear increase in amygdalar activation for the SS+SL group compared to the LL group. In contrast, subjects with ASD showed no difference dependant on 5-HTT variation.
Conclusions: These results suggest that there are variations in the influence of 5-HTT variation on the activity of the amygdale between people with ASD and controls.