Description

Fragile X Syndrome (FXS) is the leading monogenic cause of intellectual disability and autism and is associated with extremely high risk for early delays in speech and language. While the infant years are essential to speech and language development, neural mechanisms for language impairments have been studied entirely in older children and adults with FXS. Therefore, markers for speech and language impairments are unavailable in infants and young children with FXS to predict severity, test potential mechanisms, and track response to intervention. The investigators have identified a hallmark brain-based phenotype of hyperresponsiveness to sounds in adolescents and adults with FXS. This fundamental alteration in cortical responses to sound could influence early language delays, but this phenotype has not been explored in infants or toddlers with FXS.

Specifically, in this study the investigators will use simultaneous EEG/fNIRS during presentation of simple speech, stories, and nonspeech sounds to quantify and localize auditory hypersensitivity and neural differentiation in 30 preschoolers with FXS. The investigators will assess specificity through comparison with 30 typically developing controls and 30 mental-age matched children with a history of premature birth and language delays. In addition, the investigators will complete a longitudinal study (3 timepoints) of 15 infants with FXS and 15 TDC controls, with the first visit completed between 6 and 12 months of age. At each visit, the investigators will measure speech and hearing alongside cortical responses to sounds. In combination with quantitative assessment of linguistic complexity in each infant's home environment, the investigators will develop a potential model linking brain-based indicators with emergence of language delays in FXS