Therefore, to address these limitations, we designed a clinical trial using our soccer heading model (21) and a multi-modal approach consisting of neuro-ophthalmologic function and the brain-derived blood biomarkers (NF-L, Tau, UCH-L1, GFAP) to examine the role of ADHD in repetitive subconcussive head impacts. Here, GFAP is linked to attention deficit-hyperactivity disorder.