Amygdala-Hippocampal Connectivity Is Associated With Endogenous Levels of Oxytocin and Can Be Altered by Exogenously Administered Oxytocin in Adults With Autism.

Background: Oxytocin (OT) plays a pivotal role in interpersonal bonding, affiliation, and trust, and its intranasal administration is increasingly considered as a potential treatment for autism spectrum disorder.

Methods: We explored whether variations in endogenous salivary OT concentration are related to interindividual differences in core autism symptoms and expressions of attachment in 38 male adults with autism spectrum disorder. Further, resting-state functional magnetic resonance imaging was adopted to specifically explore whether interindividual differences are reflected in the intrinsic network organization of key regions of the central oxytocinergic system.

Results: Positive correlations were identified between peripheral OT and expressions of secure attachment (the State Adult Attachment Measure and the Inventory of Peer Attachment), but no significant relationships were identified with scales assessing core autism symptom domains (the Social Responsiveness Scale and the Repetitive Behavior Scale). At the neural level, higher levels of endogenous OT were associated with lower degrees of interregional functional coupling between the amygdala and hippocampal regions. Interestingly, a single dose of exogenously administered OT induced a further reduction in amygdala-hippocampal connectivity, indicating that a higher availability of OT can alter the degree of amygdala-hippocampal connectivity.

Conclusions: The identified associations between the oxytocinergic system, expressions of secure attachment, and amygdala-hippocampal pathways are anticipated to be of relevance for understanding the role of OT in modulating appropriate neural and physiological responses to stress and restoring homeostasis.