PROJECT SUMMARY/ABSTRACT
Despite the impairment in fragile X syndrome (FXS) and the fragile X premutation (FXpm), surprisingly little
research has examined the underpinnings of these impairments. One potential factor that contributes to
impairment is autonomic nervous system (ANS) dysfunction. Elevated physiological arousal, reflecting ANS
dysfunction, has long been implicated as contributing to learning impairments and atypical behavior in FXS.
While ANS dysfunction has been linked to impairment in both FXS and FXpm, research has not examined the
presence, onset, developmental trajectory, or developmental consequences of ANS dysfunction or how
molecular-genetic factors are associated. This project addresses these critical gaps with the following specific
aims: (1) Identify the onset and developmental trajectory of baseline ANS dysfunction through prospective
longitudinal assessment at 6, 9, 12, and 24 months in FXS (n=30 males) and FXpm (n=30; 15 males and 15
females) contrasted to typical controls (n=45; 30 males and 15 females); (2) Determine how molecular-genetic
variation relates to the onset and/or developmental trajectory of ANS dysfunction in FXS and FXpm; (3)
Characterize behavioral and ANS reactivity to sensory stimuli through prospective longitudinal assessment at
6, 9, 12, and 24 months in FXS and FXpm; and (4) Document the consequences of ANS dysfunction across
infancy on sensory processing impairments, adaptive skills, ASD symptoms, and social communication,
concurrently and at 24 months in FXS and FXpm. This work will have tremendous impact by greatly expanding
information on the mechanistic underpinnings, biological pathways, and timing of symptom progression, which
is essential to identify targets and timing of treatment to reduce symptom severity in FXS and FXpm. Our focus
on infancy is critical, as evidence has documented that intervention provided early in life has the potential to
accelerate development and improve developmental trajectories over time in a multi-dimensional manner.
