The effects of oxytocin in autism

Background: Oxytocin is considered as the hormone of calm, healing and love, and it plays an important role in establishing and maintaining social relationships. As autism is characterized by difficulties in social relationships, a dysregulated oxytocin system could possibly be an underlying factor. Aim: To investigate treatment effects of oxytocin in adults with an Autistic Spectrum Disorder (ASD) on affective empathy.Methods: A randomized placebo-controlled cross-over trial investigated the effects of oxytocin nasal spray on oxytocin blood levels and affective empathy in young men with autism (n = 32) and neurotypicals (n = 30). Brain responses (EEG Event Related Potentials) and cardiac evoked responses (ECG) were recorded while participants viewed (IAPS) pictures with or without humans. Blood samples were taken before and after taking the nasal spray in order to validate absorption.Results: Surprisingly, we found evidence for enhanced blood levels of oxytocin at baseline in high functioning males with autism, especially in those with high intelligence. Oxytocin nasal spray induced a tenfold increase in blood levels in males with and without autism. Blood levels may however not reflect brain levels of oxytocin. Therefore we looked into the effects on the brain responses and centrally controlled heart rate responses to empathy evoking pictures. A subgroup of men with autism had lower empathic orienting responses to positive human emotions, which improved after treatment with oxytocin nasal spray. This subgroup was characterized by high scores (15+) on the Personal Distress (PD) scale of the Interpersonal Reactivity Index (IRI). Those with higher baseline levels of oxytocin also showed a higher treatment effect.Conclusion: Only a subgroup of men with ASD appears to benefit from oxytocin nasal spray for enhancing affective empathy; those who are sensitive to distress of others. Higher baseline levels of oxytocin also predicted a higher treatment effect.