Reduced EEG Complexity and Its Association with Social Communication in Adults with Autism Spectrum Disorder: A Multiscale Entropy Study

Reduced EEG complexity, measured by multiscale entropy (MSE), is observed in adults with autism spectrum disorder (ASD) compared to typically developing (TD) individuals. This reduced complexity, which is associated with a slower effective sampling rate, is consistent across various conditions. Specifically, during eyes-closed rest and two movie viewing conditions - Inscapes featuring abstract visual patterns, and Partly Cloudy, an emotionally engaging social narrative - adults with ASD display lower MSE at longer temporal scales (16-30) than TD individuals.

The association between this reduced longer-scale MSE and social communication abilities, as measured by the Autism Diagnostic Observation Schedule, Second Edition (ADOS-2), is noteworthy. Across diagnostic groups, a lower MSE correlates with higher ADOS-2 scores related to social affect (SA). Additionally, when comparing empathic-pain and mentalizing events in the Partly Cloudy movie to non-social windows in the Inscapes movie, ASD participants exhibit a smaller difference in event-related MSE change compared to TD participants.

Among TD participants, a significant increase in MSE change is observed during Social windows compared to Non-Social windows.

However, this discrepancy is not observed among ASD participants. While the study acknowledges limitations such as a modest sample size and the absence of an independent replication cohort, as well as short event windows that limit the precision of MSE estimation, the findings suggest that reduced longer-scale MSE in adults with ASD is linked to higher ADOS-2 SA scores.

Furthermore, the study indicates that ASD participants show attenuated differentiation in longer-scale MSE between socially relevant and matched non-social windows, as opposed to TD participants who display a significant difference.