Normative modeling of intrinsic brain activity reveals multiscale heterogeneity in autism spectrum disorder

Autism spectrum disorder (ASD) is characterized by profound clinical and biological heterogeneity, which limits the reproducibility and individual specificity of findings from traditional case-control studies. However, quantitative characterization of individualized patterns of spontaneous neural activity and their biological correlates remains limited in ASD. Resting-state functional magnetic resonance imaging data, including 349 individuals with ASD and 459 typical controls, from the Autism Brain Imaging Data Exchange database were used to characterize spontaneous neural activity via the amplitude of low-frequency fluctuations (ALFF). Non-negative matrix factorization was applied to extract latent functional factors from ALFF patterns. Normative modeling was then employed to construct normative trajectories and quantify individual-level deviations in ASD relative to typical development. Subsequently, clustering was utilized to identify neurobiological subtypes based on individualized deviation profiles, and representational similarity analysis was used to examine their clinical associations. Finally, spatial correlations with transcriptomic data, neurotransmitter maps, and cognitive functional domains were explored to delineate the multiscale biological correlates of functional factors. Five latent factors spanning socio-sensorimotor integration, action-related processing, executive control, emotional processing, and attentional processing domains were successfully identified, revealing two neurobiologically distinct subtypes of ASD. Subtype-specific associations were found between individualized functional deviation profiles and clinical symptoms. Furthermore, distinct spatial associations between functional factors and gene expression profiles as well as neurotransmitter systems were observed. This study maps individualized functional heterogeneity in ASD and provides multiscale insights into the biological correlates underlying functional alterations.