Background
ASD, impairments in social communication, Autism spectrum disorder, early-onset neurodevelopmental condition, repetitive behaviors, autism
Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by impairments in social communication and interaction, combined with restricted and repetitive behaviors and interests [Following a myriad of single-dose proof-of-principle studies [Given that autism is an early-onset neurodevelopmental condition, it is important to extend these insights to pediatric populations, allowing evaluations of the efficacy of OT administration within an early developmental window and whether it can be facilitatory for enriching social behaviors and experiences from an early age onwards. To date, a handful of trials explored the effects of multiple-dose OT administration in children with ASD. Two initial trials reported a consistent pattern of results, indicating improvements in the social domain (parent-reported social responsiveness) after 5 weeks of OT administration (12 IU 2x/day) in 3- to 6-year-old children with ASD (Several factors have been put forward to understand these inconsistent results, ranging from heterogeneity in trial design (e.g., parallel versus crossover design, adopted outcomes, dosing scheme) to variation in participant characteristics. For instance, the above-mentioned well-powered confirmatory trial covered a broad age range (3–17 years) [Here, results are presented from a single-center, randomized, double-blind, placebo-controlled clinical trial (RCT with parallel design), testing efficacy on outcomes of social functioning and safety of multiple-dose OT administration (4 weeks of twice daily intranasal administration of 12 IU) in a representative sample of 8- to 12-year-old children with ASD (40 OT/40 placebo). Accordingly, by examining OT administration effects in a relatively strict age range of pre-pubertal, school-aged children, the current trial particularly aimed to minimize the potential influence of sample heterogeneity on treatment outcome. Further, following prior observations of long-lasting retention effects of OT administration in adults with ASD [Finally, a series of exploratory analyses were conducted to examine whether individual variation in treatment response may relate to particular moderator variables. First, considering prior notions that expectancies about allocated treatment can impact treatment outcome [