Salivary Oxytocin Levels in Children With and Without Autism: Group Similarities and Subgroup Variability

Background: Oxytocin (OXT), a neuropeptide involved in social bonding, has been proposed as a potential biomarker for autism spectrum disorder (ASD) due to its role in modulating social behaviors. However, prior studies on peripheral OXT levels in individuals with ASD have yielded inconsistent results, partly due to methodological and developmental variability. This study aimed to compare baseline salivary OXT concentrations between children with ASD and typically developing controls. Methods: In this cross-sectional, case-control study, salivary OXT levels were measured in 35 children aged 6-9 years (18 with ASD, 17 controls) using a standardized ELISA protocol. Samples were collected under controlled conditions and analyzed in duplicate. Between-group differences in raw and log-transformed OXT levels were examined using t-tests. Subgroup analyses were conducted by sex, and correlations with autism symptom severity (Aberrant Behavior Checklist, ABC) were assessed within the ASD group. Results: Children with ASD showed higher mean salivary OXT levels than controls (21.5 pg/mL vs. 14.0 pg/mL), but the difference was not statistically significant (Welch's t = -1.79, p = 0.088). Log transformation of OXT values confirmed the non-significant group difference (t = 1.68, p = 0.102). Female participants with ASD had significantly higher OXT than female controls (p = 0.048), while no difference was observed among males. OXT levels did not significantly correlate with autism severity (r = -0.04, p = 0.88). Conclusions: Baseline salivary OXT levels do not significantly differ between children with and without ASD and do not correlate with behavioral symptom severity. However, elevated OXT in females with ASD warrants cautious interpretation and further investigation. Salivary OXT may not be a reliable standalone diagnostic biomarker but could have exploratory value for understanding sex-specific neurobiological profiles in autism.