This is a randomized, double-blind, placebo-controlled clinical study of CoQ efficacy in a crossover design. Patients will be screened, enrolled, and studied in the outpatient clinic of the Thomas Center for Down Syndrome at CCHMC. All patients will be randomly assigned to either a liquid product (LiQ-NOL®) and an identical placebo liquid. Study drug and placebo will be administered twice a day (morning and evening).
