A – 99 Left Brain, Left Hand? Rethinking Language Lateralization in Autism

Abstract Objective This study investigates whether handedness moderates social communication and expressive language abilities in children with Autism Spectrum Disorder (ASD), measured by the Autism Diagnostic Observation Schedule (ADOS) and Vineland Adaptive Behavior Scales (VABS). Given the link between language abilities and the left brain hemisphere, we examined whether left-handedness impacts social communication and expressive language deficits in ASD. Method Data from the Autism Brain Imaging Data Exchange (ABIDE I) included 49 participants (43 male and 6 female) with complete ADOS Total scores, VABS Expressive Language V-scores, and handedness scores. Handedness was analyzed as a moderator in the relationship between ADOS Total scores and VABS Expressive Language V-score using a hierarchical regression model with an interaction term. Data Processing and Analysis was performed using Julius AI. Results The hierarchical regression revealed that ADOS Total scores did not significantly predict Vineland Expressive Language scores (R2 = 0.00, F(1,47) = .01, p = 0.9201). Adding Handedness marginally improved R2 (ΔR2 = 0.0249, F(2,46) = .59, p = 0.5576). The interaction term (ADOS x Handedness) was nonsignificant (ΔR2 = 0.0004, F(1,45) = 0.0194, p = 0.8898). Indicating no moderating effect of handedness. Conclusion Handedness did not significantly influence social communication or expressive language abilities in children with ASD. These results align with prior research, suggesting brain lateralization does not mediate expressive language abilities in this population. Future research should explore atypical cerebral hemisphere organization in children with ASD in relation to handedness and language-associated cortical areas.