Concerning pharmacological therapies, there is evidence that selective serotonin reuptake inhibitors (SSRIs), the first-line pharmacological treatment for OCD [13], reduce fronto-limbic responses to threatening stimuli in non-psychiatric volunteers [56, but see 57] and are associated with lower limbic response during emotion processing and symptom provocation in OCD [36]. Further, stronger functional connectivity between the serotonergic raphe nuclei and temporal and limbic regions including the amygdala predicts better response to SSRIs in OCD [58]. Thus, SSRIs may improve OCD symptoms in part by reducing excessive limbic activity. SSRIs can also reduce IU [59], though the mechanism underlying this improvement has not been studied.
