Coenzyme Q10 in Huntington's Disease (HD)

Huntington's disease (HD) is a slowly progressive disorder that devastates the lives of those affected and their families. There are no treatments that slow the progression of HD, only mildly effective symptomatic therapies are available. The purpose of this trial is to find out if coenzyme Q10 (CoQ) is effective in slowing the worsening symptoms of HD. In this study, researchers also will learn about the safety and acceptability of long-term CoQ use by determining its effects on people with HD. Participants in this trial will be randomly chosen to one of two groups. Group 1 will receive CoQ (2400 mg/day), and group 2 will receive a placebo (an inactive substance). Researchers will compare the change in total functional capacity (TFC)-a measure of functional disability-in the two groups. The TFC is a valid and reliable measure of disease progression and is particularly responsive to change in the early and mid-stages of HD. Researchers will also compare the changes in other components of the Unified Huntington's Disease Rating Scale '99 (UHDRS) including: the total motor score, total behavioral frequency score, total behavior frequency X severity score, verbal fluency test, symbol digit modalities test, Stroop, interference test, functional checklist, and independence scale scores. The groups will also be compared with respect to tolerability, adverse events, vital signs, and laboratory test results as measures of safety.