The effect of the serotonin transporter polymorphism (5-HTTLPR) on empathic and self-conscious emotional reactivity.

We examined the relationship between a functional polymorphism of the serotonin transporter gene (5-HTTLPR) and individual differences in emotional reactivity in two laboratory studies. In Study 1, empathic responding and physiological reactivity to viewing films of others in distress were assessed in healthy adults in three age groups. In Study 2, emotional responding to watching oneself in an embarrassing situation was assessed in healthy adults and in patients with neurodegenerative diseases. In Study 1, participants with two short alleles of 5-HTTLPR reported more personal distress and showed higher levels of physiological responses in response to the films than participants with long alleles. In Study 2, participants with two short alleles reported more anger and amusement and displayed more emotional expressive behaviors in response to the embarrassing situation than participants with long alleles. These two findings from diverse samples of participants converge to indicate that individuals who are homozygous for the short allele variant of 5-HTTLPR have greater levels of emotional reactivity in two quite different socially embedded contexts.