Effects of Subconcussive Head Impacts on Neural Integrity and Function in ADHD

The purpose of this study is to examine the acute neural responses to subconcussive head impacts in individuals with Attention-deficit/hyperactivity disorder (ADHD). The study is designed to identify the effects of 10 controlled soccer headings in college-aged soccer players diagnosed with ADHD and without ADHD, through the use of neural-injury blood biomarkers, functional and diffusion MRI, and ocular-motor function across three acute timepoints. The central hypothesis is that neuronal structural, physiological, and functional impairments from subconcussive head impacts will be amplified by ADHD. The neural-injury blood biomarkers neurofilament light (NF-L), glial fibrillary acidic protein (GFAP), ubiquitin C-terminal hydrolase-L1 (UCHL-1), and Tau will be measured in plasma, with the hypothesis that 10 soccer headings will significantly increase plasma NF-L levels in both groups at 24h post-heading compared to baseline, but this increase will be higher in the ADHD group; plasma UCH-L1, GFAP, and Tau levels will increase significantly after 10 headings in the ADHD group at 2h and 24h post-heading, but levels in the non-ADHD group will remain consistent throughout the time points. It is also hypothesized that repetitive subconcussive head impacts will impair neurocognitive function, as measured by regional changes in fMRI activation during working memory and attention-based tasks, in the ADHD group. Ten headings will significantly alter fMRI activation in the ADHD group from baseline. This impairment will not be observed in the non-ADHD group, rather the non-ADHD group will show consistent fMRI activation even after 10 headings. White matter microstructure will be measured by diffusion imaging metrics, with the hypothesis that 10 soccer headings will significantly disrupt microstructure in the ADHD group compared to baseline, but not in the non-ADHD group. The study will also assess neuro-ophthalmologic function as measured by the King-Devick test (KDT) and oculomot