Peripheral oxytocin but not vasopressin concentrations are associated with language skills in young autistic children.

BACKGROUND: Autistic children often have language development problems, and language ability is a key contributor to social behavior. There is increasing evidence for altered circulating concentrations of the neuropeptides oxytocin and vasopressin in young autistic children and exogenous treatment with either peptide can improve social symptoms. However, to date, the importance of both tonic endogenous concentrations of these two peptides and increased ones following exogenous administration for language development in autistic children has not been established. METHODS: Here we have firstly investigated the associations between blood oxytocin and vasopressin concentrations and vocabulary use and other language/communication measures in a cohort of 148 young autistic children (3-7.5 years) and also in saliva samples from another cohort of 40 autistic children (2-6 years). Furthermore, we examined whether specific improvements in language communication occurred in this latter cohort following 6 weeks of intranasal oxytocin treatment administered every other day followed by positive social interactions previously shown to improve overall social symptoms. RESULTS: Baseline plasma oxytocin, but not vasopressin, concentrations were significantly associated with both vocabulary development and other language/communication measures after controlling for age and gender in the main cohort of children and additionally in a smaller subset of them even if developmental quotient was controlled for. There was a similar association after controlling for age, gender, and the general adaptability composite score between baseline saliva oxytocin concentrations and language/communication scores in the second independent cohort. In this latter cohort, intranasal oxytocin treatment facilitated language/communication scores across several different scales, and improvement was correlated with post-treatment increases in saliva oxytocin concentrations and significantly indirectly mediated by them. CONCLUSIONS: Overall, this analysis provides support for a potentially important role of oxytocin in language development in autistic children and suggests that it may have therapeutic utility for individuals with language problems.