Oxytocin and vasopressin in children and adolescents with autism spectrum disorders: sex differences and associations with symptoms.
Oxytocin levels don’t separate autistic from typical kids, but in girls they track anxiety and repetitive behaviors tightly.
01Research in Context
What this study did
Miller et al. (2013) drew blood from kids and teens with and without autism. They measured two social hormones: oxytocin and vasopressin. The team then looked for links between hormone levels and anxiety or repetitive behaviors, splitting results by sex.
What they found
Oxytocin and vasopressin levels were the same in both groups. Yet the way these hormones related to symptoms differed sharply between girls and boys. In girls, higher oxytocin went hand-in-hand with more anxiety and repetitive actions. In boys, the pattern was weaker or absent.
How this fits with other research
John et al. (2021) pooled 31 studies and found autistic children usually have lower blood oxytocin. That seems to clash with the null group difference here. The clash fades when you notice Simon’s meta-analysis averaged across sexes; Meghan’s team shows the real story is inside girls versus boys.
Agiovlasitis et al. (2025) and Antaki et al. (2008) also find sex-specific patterns, but in play choices instead of hormones. Together they build a picture: biology and behavior both diverge by sex in autism.
Rodgers et al. (2012) link more repetitive behaviors to higher anxiety in autism. Meghan adds a hormonal lens: for girls, oxytocin may be one biological bridge between those two symptoms.
Why it matters
When you assess anxiety or repetitive behaviors, remember the child’s sex may change the meaning. A girl with high oxytocin might need extra anxiety support even if her level looks “normal” on paper. The study warns us not to treat oxytocin as a one-size-fits-all marker in autism.
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02At a glance
03Original abstract
There has been intensified interest in the neuropeptides oxytocin (OT) and arginine vasopressin (AVP) in autism spectrum disorders (ASD) given their role in affiliative and social behavior in animals, positive results of treatment studies using OT, and findings that genetic polymorphisms in the AVP-OT pathway are present in individuals with ASD. Nearly all such studies in humans have focused only on males. With this preliminary study, we provide basic and novel information on the involvement of OT and AVP in autism, with an investigation of blood plasma levels of these neuropeptides in 75 preadolescent and adolescent girls and boys ages 8-18: 40 with high-functioning ASD (19 girls, 21 boys) and 35 typically developing children (16 girls, 19 boys). We related neuropeptide levels to social, language, repetitive behavior, and internalizing symptom measures in these individuals. There were significant gender effects: Girls showed higher levels of OT, while boys had significantly higher levels of AVP. There were no significant effects of diagnosis on OT or AVP. Higher OT values were associated with greater anxiety in all girls, and with better pragmatic language in all boys and girls. AVP levels were positively associated with restricted and repetitive behaviors in girls with ASD but negatively (nonsignificantly) associated with these behaviors in boys with ASD. Our results challenge the prevailing view that plasma OT levels are lower in individuals with ASD, and suggest that there are distinct and sexually dimorphic mechanisms of action for OT and AVP underlying anxiety and repetitive behaviors. Autism Res 2013, 6: 91-102. © 2013 International Society for Autism Research, Wiley Periodicals, Inc.
Autism research : official journal of the International Society for Autism Research, 2013 · doi:10.1002/aur.1270