Background

Autism spectrum disorder (ASD) is characterized by social communication difficulties, restricted and repetitive behaviors, and sensory atypicalities. Its pathophysiology remains poorly understood, and no diagnostic biomarker is currently available. However, studies support the hypothesis of an imbalance in the neuronal excitation/inhibition (E/I) balance. Beta and gamma oscillatory powers are described in the literature as indirect electrophysiological features reflecting network dynamics related to this balance. This study takes a dimensional approach to investigate whether alterations in these rhythms are linked to the severity of autistic symptoms.

Methods

A total of 127 individuals with ASD, including a sensory-assessed subgroup of 57 participants, all aged 5 to 17 years, underwent resting-state high-density electroencephalography (HD-EEG) recordings with eyes closed. Absolute power was extracted from the beta and gamma frequency bands for six regions of interest. Multiple linear regression models were used to investigate the relationships between beta and gamma powers and the clinical dimensions of ASD, while controlling for the effects of age and sex.

Results

Beta power was positively correlated with sensory hyposensitivity across all regions (all corrected p<.02, n = 57) and with sensory hypersensitivity in the central, parietal, and left temporal regions (all corrected p<.05, n = 57). In addition, an exploratory result suggested that an increase in gamma power may be associated with the severity of restricted and repetitive behaviors (RRBs) in the right temporal region (uncorrected p=.01, n = 127).

Conclusions

These innovative results call for further analysis, including an investigation of other electrophysiological markers providing indirect profiles of E/I balance. Nevertheless, they open new avenues for a better understanding of the neurobiological processes and early diagnosis of ASD.