· JAMA neurology 2014 · randomized controlled trial · n=600

A randomized clinical trial of high-dosage coenzyme Q10 in early Parkinson disease: no evidence of benefit.

Cited 402 times in the scientific literature.

Level 2 - randomized trial

Multi-center phase III randomized, double-blind, placebo-controlled trial

PubMed 24664227 · doi:10.1001/jamaneurol.2014.131 · record verified 2026-08-27

What was done

A multicenter, double-blind, randomized controlled trial across 67 North American sites evaluated whether high-dose coenzyme Q10 (CoQ10) slows disease progression in early Parkinson disease (PD). A total of 600 participants (mean age 62.5 years, 66% male, mean baseline UPDRS score 22.7, diagnosed within 5 years, not requiring dopaminergic therapy) were randomized to placebo, 1200 mg/day of CoQ10, or 2400 mg/day of CoQ10. All participants received 1200 IU/day of vitamin E. Participants were followed for 16 months or until requiring dopaminergic therapy. The primary outcome was the change in total UPDRS score (Parts I–III) from baseline to final visit.

What was found

The study was terminated early after reaching a prespecified futility criterion. Adjusted mean changes (worsening) in total UPDRS scores from baseline to final visit were 6.9 points in the placebo group, 7.5 points in the 1200 mg/d group (P = .49 vs placebo), and 8.0 points in the 2400 mg/d group (P = .21 vs placebo). A total of 267 participants required dopaminergic therapy (94 placebo, 87 with 1200 mg/d, 86 with 2400 mg/d), and 65 withdrew prematurely (29 placebo, 19 with 1200 mg/d, 17 with 2400 mg/d). Both active groups showed slight non-significant adverse trends relative to placebo.

Why it matters

Despite prior preclinical and phase II signals, high-dose CoQ10 does not slow functional decline in early Parkinson disease.

Limits

The trial was stopped early due to futility, limiting observation duration. Results apply specifically to early-stage, untreated PD and cannot be generalized to advanced disease. All treatment groups received concurrent vitamin E, meaning CoQ10 monotherapy was not directly evaluated.

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