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

Importance: Coenzyme Q10 (CoQ10), an antioxidant that supports mitochondrial function, has been shown in preclinical Parkinson disease (PD) models to reduce the loss of dopamine neurons, and was safe and well tolerated in early-phase human studies. A previous phase II study suggested possible clinical benefit.

Objective: To examine whether CoQ10 could slow disease progression in early PD.