Inter-brain synchrony to delineate the social impairment in autism spectrum disorder: a systematic review on hyperscanning studies.

Autism spectrum disorder (ASD) is a common neurodevelopmental disorder marked by significant deficits in social interaction and restricted repetitive behaviors. Despite rigorous research efforts, the early and effective diagnosis and intervention of ASD remain challenging, due primarily to its considerable heterogeneity and complex neurobiological underpinnings. Traditional neuroimaging techniques have largely focused on individual brain responses to social stimuli, often overlooking the critical interactive dynamics that contribute to social impairments in individuals with ASD. This review explored hyperscanning, an innovative neuroimaging approach that features simultaneous recording of brain activity across multiple individuals, to enhance our understanding of the neural mechanisms underlying social difficulties in ASD. By searching published articles conducted between 2000 and 2024, we found eight empirical studies conducted between 2012 and 2024, which employed various brain imaging techniques. We analyzed and summarized participant demographics, experimental designs, and key outcomes, with a particular focus on inter-brain synchrony (IBS) as a measure of social engagement and the quality of interpersonal interactions. Our review identified specific patterns of neural synchrony that correlate with the severity of ASD symptoms. Furthermore, we critically evaluated the limitations of current studies and proposed future research directions, highlighting the need for more nuanced hyperscanning methodologies. Such advancements could significantly deepen our understanding of social impairments in ASD and inform targeted intervention strategies. This comprehensive review aimed to assess the potential of hyperscanning techniques to propel progress in ASD research and intervention, ultimately contributing to more effective clinical practices.