Does high-dose coenzyme Q10 improve oxidative damage and clinical outcomes in Parkinson's disease?

Evidence on the efficacy of high-dose coenzyme Q(10) (CoQ(10)) in Parkinson's disease (PD) is conflicting. An open-label dose-escalation study was performed to examine the effects of CoQ(10) on biomarkers of oxidative damage and clinical outcomes in 16 subjects with early idiopathic PD. Each dose (400, 800, 1200, and 2400 mg/day) was consumed daily for 2 weeks. High-dose CoQ(10) was well tolerated and improvements in the total Unified Parkinson's Disease Rating Scale (median, 37 vs. 27; p = 0.048) were observed following study completion. Plasma F-2-isoprostanes (adjusted for arachidonate) were significantly reduced in the 400-1200 mg/day dose range, but increased at 2400 mg/day dosage. A similar pattern of change was observed with serum phospholipase A(2) activities. Levels of plasma all trans-retinol, plasma total tocopherol, serum uric acid, and serum total cholesterol were unchanged despite an increase in the CoQ(10) dosage. Subjects with symptomatic benefits from CoQ(10) (decrease in total UPDRS > 10 points) had lower baseline plasma ubiquinol (p = 0.07, Mann-Whitney U test) and decreased F-2-isoprostanes per unit arachidonate (p = 0.04, Wilcoxon Signed-Ranks test). These results lead to the hypothesis that the therapeutic response to CoQ(10) depends on baseline levels of ubiquinol and whether the dosage of CoQ(10) used can ameliorate the burden of oxidative damage.