Resting state aperiodic and periodic EEG activity in preschool-aged autistic children: differences from neurotypical peers and links to language skills.

backgroundThe neural mechanisms underpinning language development in autism spectrum disorder remain unclear. While prior studies have identified associations between resting-state EEG absolute power and language skills in autistic children, none have examined the distinct roles of aperiodic and periodic activity decomposed from the absolute power spectra on language development in autistic children.

methodsAt the group level, we examined resting-state power spectra differences between 64 neurotypical and 64 age-matched autistic children from 2 to 6 years old, as well as within the autistic group based on language impairment status. At the individual level, we examined whether aperiodic and periodic EEG features were associated with concurrent language skills measured by natural language samples and a standardized language assessment in participants with autism spectrum disorder.

resultsAutistic children exhibited higher aperiodic offset, but not aperiodic slope, compared to their neurotypical peers. While we did not find significant differences in peak alpha frequency and alpha peak amplitude between neurotypical and autistic children, after separating the autistic group by language impairment status, we found that autistic children with language impairment had significantly lower alpha peak amplitude compared to autistic children without language impairment and their age-matched neurotypical peers. Regarding the brain-language association, autistic children with lower aperiodic offset demonstrated better concurrent expressive and receptive language skills, but not nonverbal developmental quotient. Autistic children with higher alpha peak amplitude demonstrated better concurrent language and nonverbal developmental skills. LIMITATIONS: Findings were based on cross-sectional data from children with relatively higher socioeconomic backgrounds. Future studies are needed to explore the longitudinal relation between resting-state EEG aperiodic and periodic features and language development in autistic children, while accounting for potential confounding effects of demographic variability and data quality.

conclusionsThe characteristic features of resting-state power differences vary when comparing autistic children to neurotypical peers versus comparing within the autistic subgroup based on language phenotypes. These findings underscore the importance of considering the heterogeneity of the autism spectrum when investigating the neural mechanisms underlying language development in autistic children.