Study Finds Autism-Related Brain Excitation-Inhibition Imbalances Vary by Region and Age
A large cross-sectional MEG study found that cortical excitation-inhibition (EI) balance in autism spectrum disorder (ASD) varies significantly by brain region and developmental stage rather than being a uniform, static deficit. Researchers analyzed resting-state brain recordings from 172 individuals aged 6–32, comparing 80 with ASD to 92 typically developing peers across childhood, adolescence, and adulthood. The findings challenge a simple global EI imbalance model of autism and may help explain the wide variability in ASD presentations across individuals and ages.
Using resting-state magnetoencephalography (MEG) and a functional EI (fEI) metric derived from critical brain dynamics, researchers examined cortical excitation-inhibition balance across 500 brain parcellations in 80 individuals with ASD and 92 typically developing (TD) controls, spanning ages 6 to 32. At the broadest level, overall topographic EI patterns were similar between groups, but age-stratified analyses revealed that children with ASD showed elevated global fEI while adolescents with ASD showed decreased fEI compared to TD peers, with no significant group difference in adulthood. A region-specific analysis identified persistently lower fEI in the right dorsolateral prefrontal cortex in ASD across all ages, independent of developmental stage. In the left inferior parietal cortex, TD individuals showed a significant age-related increase in fEI that was absent in the ASD group, indicating diverging developmental trajectories in that region. Additionally, fEI in the paracentral and precuneus regions correlated with ASD symptom severity, linking the neural measure to behavioral outcomes. The study's cross-sectional design and relatively modest subgroup sizes, particularly in childhood, are important limitations. Overall, the results argue against a single, global EI imbalance account of ASD and instead point to a regionally and developmentally nuanced picture.
What's missing
The study is a preprint posted to bioRxiv and has not yet undergone formal peer review, which limits confidence in the findings. As a cross-sectional design, it cannot directly track individual developmental change over time; longitudinal data would be needed to confirm the diverging trajectories observed. Subgroup sizes in childhood are small (N=18 ASD, N=16 TD), reducing statistical power for that age band. The fEI metric is a relatively novel, indirect proxy for EI balance and has not been fully validated against direct electrophysiological or pharmacological measures of excitation and inhibition. The study does not report medication status of ASD participants, which could influence MEG-derived neural measures.
What different sources said
- bioRxivCenter
Cortical Excitation-Inhibition Balance in Autism Varies by Brain Region and Age
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