The investigation team propose in this study to specifically evaluate the feasibility of using oxytocin in the form of an intranasal spray in a specific population of children with autism spectrum disorder and intellectual disability. The lack of studies centered on this population on the one hand, and on the other hand the severity of challenging behaviors presented by these children, make questionable the direct transfer of methods of care used in patients who do not present these challenging behavior. In this sense, the establishment of oxytocin treatment in these children requires a preliminary phase of feasibility assessment before being able to consider a comparative trial of the randomized clinical trial type.