Abnormal functional connectivity of dynamic brain network in toddlers with autism and its correlation with symptoms

Background: The pathogenesis of autism spectrum disorder(ASD) is still unclear at present. Diagnosis mainly relies on the symptoms of the individual and relevant scales, which is highly subjective. Moreover, the majority of diagnoses are made after the age of 3, seriously delaying the best treatment opportunity. This study aims to explore the brain functional connectivity (FC) of toddlers with ASD aged 1 to 3 years old to characterize the related neuro-pathological mechanisms and attempt to provide objective biomarkers for the early diagnosis of ASD. Methods: Magnetic resonance imaging data of 41 toddlers diagnosed with ASD and 23 age- and sex-matched normal development control (NC) were collected. The evaluation focused on the between-group differences in the temporal characteristics of state, and subsequently, a correlation analysis was conducted to examine the relationship between these differences and autistic traits in individuals with ASD. Results: Compared to NC group, toddlers with ASD exhibited a significant increase in mean dwell time(MDT) and occurrence rate(OR) in State 1, characterized by weaker within-network connectivity and a significant reduction in MDT in State 4,which distinguished by stronger connectivity, demonstrating modularization within various networks. Correlation analysis showed that the Childhood Autism Rating Scale(CARS) scores and MDT were positively correlated in State 1, and significantly positively correlated with number of transitions(NT) between states. MDT in State 4 was negatively correlated with sensation scores in the Autism Behavior Checklist (ABC). Conclusions: Toddlers with ASD show disrupted connectivity networks, while abnormal dynamic brain FC correlates with ASD severity. These findings suggest new neural mechanisms underlying ASD, providing possible neuroimaging markers for early diagnosis.