Functional connectivity alterations in high-functioning preschool boys with autism spectrum disorder

Information processing impairments are associated with the social and sensory symptoms of autism spectrum disorder (ASD). Functional connectivity forms the basis of information exchange and integration. Previous research has shown atypical functional connectivity patterns in school-aged children, adolescents, and adults with ASD. However, connectivity alterations in children with ASD in preschool years, a critical period for brain and cognition function development, are yet to be explored. Here, we compared resting-state EEG functional connectivity between high-functioning preschool boys with ASD and typically developing (TD) peers and investigated the relationships between functional connectivity and symptom severity of ASD as measured by the Childhood Autism Rating Scale (CARS). Network-based statistic (NBS) identified five intrahemispheric (left prefrontal-left central, left frontal-left central, left central-left occipital, right central-right parietal, and right temporal-right parietal) and four interhemispheric (left prefrontal-right central, left central-right parietal, left occipital-right parietal, and left parietal-right temporal) decreased long-range connections in the delta (1-4 Hz) band in ASD. Cliff's delta analysis indicated all of the alterations were of large effect sizes. Correlation analysis further revealed significant relationships between dysconnectivity and symptom severity of ASD. Findings remained significant after Benjamini-Hochberg correction. Specifically, decreased left prefrontal-right central connectivity was correlated with worse "relationship to people" and better "activity level," impaired right central-right parietal and left frontal-left central connections were individually associated with severe "listening response," and reduced left central-left occipital connectivity was related to better "taste-smell-touch response and use." In conclusion, this study suggests a trend of weakened long-range functional connectivity in high-functioning preschool boys with ASD and highlights its influence on the symptoms of ASD. Larger-scale studies are required to verify its potential as a biomarker for early screening, diagnosis, and neurophysiological intervention strategy planning of ASD.