TPH2 and Anxiety: However, we did not expect to find significant differences between TPH2 G‐703T variants on impulsivity, aggression, and anxiety (direct effect), but assumed that the relation between TPH2 G‐703T and impulsivity, aggression, and anxiety was mediated by neural structure and/or function (indirect effects), for example, of the prefrontal cortex and the amygdala.