A randomized trial shows dose-frequency and genotype may determine the therapeutic efficacy of intranasal oxytocin

Background The neuropeptide oxytocin is proposed as a promising therapy for social dysfunction by modulating amygdala-mediated social-emotional behavior. Although clinical trials report some benefits of chronic treatment it is unclear whether efficacy may be influenced by dose frequency or genotype. Methods In a randomized, double blind, placebo-controlled pharmaco-fMRI trial (150 male subjects) we investigated acute and different chronic (every day or on alternate days for 5 days) intranasal oxytocin (24IU) effects and oxytocin receptor genotype-mediated treatment sensitivity on amygdala responses to face emotions. We also investigated similar effects on resting state functional connectivity between the amygdala and prefrontal cortex. Results A single dose of oxytocin reduced amygdala responses to all face emotions but for threatening (fear and anger) and happy faces this effect was abolished after daily doses for 5 days but maintained by doses given every other day. The latter dose regime also enhanced associated anxious-arousal attenuation for fear faces. Oxytocin effects on reducing amygdala responses to face emotions only occurred in AA homozygotes of rs53576 and A carriers of rs2254298. The effects of oxytocin on resting state functional connectivity were not influenced by either dose-frequency or receptor genotype. Conclusions Infrequent chronic oxytocin administration may be therapeutically most efficient and its anxiolytic neural and behavioral actions are highly genotype-dependent in males.