Subchronic duloxetine administration alters the extended amygdala circuitry in healthy individuals

Neuroimaging studies have consistently linked depression to hyperactivation of a (para)limbic affective processing network centered around the amygdala. Recent studies have started to investigate how antidepressant drugs affect amygdala reactivity in healthy individuals, but the influence of their subchronic administration on the functional integrity of the affective neurocircuitry as a whole remains unknown. Therefore, we used functional magnetic resonance imaging in nineteen healthy volunteers to assess the effect of two weeks of administration of the combined serotonin and norepinephrine reuptake inhibitor duloxetine (60 mg) on reactivity and functional connectivity within the affective neurocircuitry in a double-blind, placebo-controlled, crossover design. Using an emotional face matching task we demonstrated that duloxetine reduced neural responses in affect processing regions including the amygdala, the anterior insula, the thalamus and the ventral aspect of the anterior cingulate cortex. Additionally, functional coupling between the amygdala and the anterior insula was enhanced by the drug. These results suggest that duloxetine attenuates the bottom-up processing of biologically salient information in an extended amygdala circuitry, while at the same time possibly potentiating the effective communication between its subparts. Since hyperactivation of the same affective neurocircuitry is thought to underlie emotional dysfunction in depression, these results suggest a putative neural mechanism through which duloxetine could normalize typical negativity biases in depression.