Watanabe T, Kuroda M, Kuwabara H, Aoki Y, Iwashiro N, Tatsunobu N, Takao H, Nippashi Y, Kawakubo Y, Kunimatsu A, Kasai K, Yamasue H (2015) Clinical and neural effects of six-week administration of oxytocin on core symptoms of autism. Brain:awv249.
Autism spectrum disorder (ASD) is a prevalent neurodevelopmental disorder but is not given established medical treatment. Despite previous literatures showing temporal positive effects of single-dose administration of oxytocin in experimental settings, until now, it is still controversial whether such potentially beneficial reactions can yield clinically therapeutic effects after long-term intervention, which is currently impeding further development of medications for the developmental disorder.
Here, we performed a randomised, double-blind, placebo-controlled, crossover trial, and found that six-week continual administration of oxytocin significantly reduced the clinically evaluated core symptoms specifically in the social domain. Critically, this clinical improvement was associated with increases in brain activity and functional connectivity in medial prefrontal cortex. Furthermore, using the same psychological task as in our recent single-dose oxytocin trial, we showed that the long and continual administration did not magnify the effect sizes seen in the single-dose intervention, which might have made it difficult for previous trials to detect significant effects of long-term administration of this neuropeptide.
The current study, to our best of knowledge, provides the first direct clinical and biological evidence for therapeutic effects of long-term oxytocin administration; in addition, this research also indicates that we still need to seek the optimal dosing regimen to maximize such effects of continual oxytocin interventions. We believe that this study provides major observations that will stimulate and guide the future development of novel medical treatments for ASD.
