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The Sensory Domain As a Target for Treatment in ASD Clinical Trials: Electrophysiological and Behavioral Markers of Therapeutic Change
Objectives: This study piloted the utility of electrophysiological and behavioral measures for assessing change in sensory reactivity during a clinical trial of insulin-like growth factor-1 (IGF-1) in children with Phelan-McDermid syndrome (PMS). PMS is one of the most common single-gene causes of ASD and sensory hyporeactivity is a prominent feature of the syndrome.
Methods: Participants included six children with PMS 5-12 years of age enrolled in an ongoing placebo-controlled, double-blind, crossover design study. Transient visual evoked potentials (VEPs) and the Sensory Assessment for Neurodevelopmental Disorders (SAND) were collected at baseline and week 12 of each study phase of the crossover. VEPs reflect the sum of excitatory and inhibitory postsynaptic potentials and provide a window into the brain to examine excitatory/inhibitory balance. The magnitude squared coherence statistic (MSC) was used to examine coherence of high-frequency oscillatory responses. The SAND is a clinician-administered observation and corresponding caregiver interview that quantifies sensory reactivity according to DSM-5 criteria for ASD (hyporeactivity, hyperreactivity, seeking).
Results: There was a significant increase in low gamma (30-36 Hz) activity following IGF-1 relative to baseline (p=.048). Notably, MSC increased in 5 of 6 patients. Significant clinical improvement was observed on the SAND Hyporeactivity Domain following IGF-1 treatment (p=.037).
Conclusions: Data collection is ongoing and preliminary results suggest that VEPs and the SAND represent two novel outcome measures for use in clinical trials for individuals with ASD and related conditions.