Associations Between Altered Auditory EEG Markers and Clinical Impairments in Fragile X Syndrome

Individuals with Fragile X syndrome (FXS) manifest clinical impairments in several domains. Previous research has shown that auditory evoked potentials (AEPs), measured using electroencephalogram (EEG), are altered in FXS, but the associations between these alterations and the symptoms observed in FXS have not been thoroughly investigated. The aim of this study was to compare AEP markers between individuals with FXS and neurotypical (NT) controls, with the main purpose of exploring how these markers are related to various clinical symptoms present in FXS.

A passive auditory oddball paradigm was presented. P1, N1, P2, N2, P3 and mismatch negativity (MMN) amplitudes and latencies were compared between 41 children and adults with FXS and 46 age-matched NT controls. Amplitudes and latencies, as well as habituation and change detection effects were compared between the groups using mixed design ANOVAs. Pearson correlations were then performed to explore associations between AEP markers and symptoms in the FXS group.

Our results showed that FXS participants had increased N1, P2 and MMN amplitudes and latencies, as well as lack of habituation and change detection effects compared to NT controls. Our correlational analyses revealed several associations between AEPs and phenotypic manifestations; notably, associations between exaggerated N1 and P2 amplitudes and more severe autistic and ADHD symptoms.

These findings confirm that abnormalities of the N1 and P2 components are robust biomarkers of altered sensory processing in FXS and suggest that these alterations may present a dose-response relation to clinical impairments in FXS.