Neural response to repeated auditory stimuli and its association with early language development in children with Fragile X syndrome

Abstract

Background: Fragile X syndrome (FXS) is the most prevalent form of inherited intellectual disability and is the most common monogenetic cause of autism. Previous studies have linked the structural and functional alterations in FXS with impaired sensory processing and sensory hypersensitivity, which may hinder the early development of cognitive functions such as language comprehension. In this study, we compared the P1 response in event-related potential (ERP) and its habituation to repeated auditory stimuli in male children (2-7 years old) with and without FXS, and examined their association with clinical measures in these two groups. Methods: We collected high-density electroencephalography (EEG) data in an auditory oddball paradigm from 12 children with FXS and 11 age- and sex-matched typically developing (TD) children. After standardized EEG pre-processing, we conducted a spatial principal component (PC) analysis and identified two major PCs --- a frontal PC and a temporal PC. Within each PC, we compared the P1 amplitude and inter-trial phase coherence (ITPC) between the two groups, and performed a series of linear regression analysis to study the association between these EEG measures and several clinical measures, including assessment scores for language development, non-verbal skills, and sensory hypersensitivity. Results: At the temporal PC, both early and late standard stimuli evoked a larger P1 response (p = 0.0037, p < 0.0001, respectively) and higher ITPC (p = 0.0402, p = 0.0027) in FXS than in TD. We observed habituation of ITPC in both groups at the frontal PC (p = 0.0149 for FXS; p = 0.0244 for TD). Linear regression analysis showed that within the FXS group reduced frontal P1 response to late standard stimuli and increased habituation were associated with better languages scores. No associations were observed with non-verbal skills or sensory hypersensitivity. Conclusion: We identified P1 amplitude and ITPC in the temporal region as a contrasting EEG phenotype between the FXS and the TD groups. P1 response and habituation in the frontal region may be reflective of the language outcome in male children with FXS. These EEG measures are potential biomarkers for early diagnosis and future language development in patients with FXS.