Early neurophysiological markers of aberrant auditory processing associated with increased risk of autism spectrum disorder: A systematic review

Importance: There is a lack of reliable early diagnostic criteria for autism spectrum disorder (ASD), despite earlier diagnosis leading to better outcomes. Objective: To evaluate the association of aberrant auditory processing (AAP) as a potential early marker of ASD risk in children under 2 years old. Methods: A systematic review of studies published between 1985 and September 2024 was conducted by searching PubMed and Web of Science. Results: The review encompassed 18 studies with 140 231 participants, and a majority (76%) of these studies found evidence that early neurophysiological changes in auditory processing are associated with later ASD risk. Specifically, prolonged auditory brainstem response (ABR) latency, reduced social stimuli selectivity, and poorer auditory brain connectivity were correlated with ASD status in later childhood. Notably, auditory habituation did not differ significantly with ASD risk. It's important to recognize that the evidence was somewhat limited by heterogeneity, small sample sizes, and inadequate reporting. Interpretation: This review identified three early neurophysiological AAP markers associated with ASD risk: ABR latency, social stimuli selectivity, and auditory brain coherence. These markers show potential for aiding in earlier ASD risk assessment in young children, potentially leading to earlier interventions. However, to fully establish the association of these AAP markers with ASD as a reliable screening tool during early childhood, future research should focus on standardized experimental protocols and adequately powered prospective cohort studies.