Interest of Oxytocin as an Adjuvant Treatment of Psycho-educational Measures in Challenging Behaviors in Children With Autism Spectrum Disorders and Moderate to Severe Intellectual Disability: Feasibility and Safety Study.

Inclusion Criteria: * Minor benefiting from a social security scheme. * Diagnosis:autism spectrum disorder according to the Diagnostic and Statistical Manual DSM -5 of severe intensity; * Comorbidities: * Moderate to severe intellectual disability * Presence of challenging behavior objectified by means of clinical examination and the ABC and ABC-I scales * Multi-professional psycho-educational and re-educational care : global and coordinated interventions associating, according to the needs, educational interventions by targeted objectives, therapeutic interventions involving functions that do not develop spontaneously, adaptation of the environment by structuring time and space, in close collaboration with the families. * If prescribed psychotropic treatments (antipsychotics, anxiolytics, hypnotics/sedatives, antidepressants, psychostimulants and antiepileptics), the dosages must be stable for 3 months\* * Understanding of French by both parents (if applicable) and ability for both parents to understand, in particular, the instructions for administering the product and to answer questionnaires. * Informed consent signed by the holders of parental authority Exclusion Criteria: * The refusal of the holders of parental authority * Pregnant girls, determined by a positive baseline blood pregnancy test * Criteria respecting the Syntocinon SPC: * Hypersensitivity to Syntocinon * Hyponatremia \< 135 mmol/L * Hypokalaemia \< 3.5 mmol/L * Hypertension or hypotension * Beh…