Objective frequency analysis of transient visual evoked potentials in activity dependent neuroprotective protein (adnp) syndrome

Abstract

Time-and frequency-domain measures of transient visual evoked potentials (tVEPs) were examined to advance understanding of neural differences in children with activity dependent neuroprotective protein (ADNP) syndrome. Stimulus conditions included short and long versions of a contrast-reversing checkerboard. Linear mixed-effects models (LMMs) were used to compare responses and assess the reliability between the time- and frequency-domain measures (i.e., amplitude, magnitude-squared coherence, enhanced signal power, total power, and noise power) of tVEPs collected on Neucodia (VeriSci Corp., USA) and EvokeDx (Konan Medical., USA) systems. LMMs were also used to examine group differences in time- and-frequency-domain measures of tVEPs collected from children with ADNP syndrome, autistic children (iASD), and typically developing (TD) children. A frequency-domain measure, H24 delay, which was calculated from the 24th harmonic frequency component, predicted P100 peak times. No significant differences were found between time-and frequency-domain measures between systems; however, enhanced signal power was the only measure that was not impacted by adaptation effects associated with the long condition. Significant group differences were found between peak-to-trough amplitudes and across four frequency-band measures. The TD group elicited the most prominent responses followed by the iASD group, and the ADNP group elicited the weakest responses. These findings suggest that iASD and ADNP syndrome are associated with reduced excitatory cortical activity. Relatedly, several children with ADNP syndrome elicited waveforms with minimal P60 peaks, but with prominent P100 amplitudes, suggesting that ADNP syndrome may be associated with relatively higher levels of neural inhibition. The findings with novel, objective frequency-domain measures applied in this investigation highlight the clinical promise of using tVEPs as a biomarker of ASD.