Science News

Co-Enzyme Q10 Study Stopped Because of Lack of Evidence that It Delays Progression of Early PD

Monday, May 30, 2011

On May 27, the National Institute of Neurological Diseases and Stroke (NINDS) announced the halt of a large clinical trial conducted by the Parkinson Study Group (PSG) on the potential beneficial effects of the dietary supplement coenzyme Q10 (CoQ10) on reducing the progression of early Parkinson’s disease (PD). Their reason: a mid-study analysis suggested that there is no improvement in the CoQ10-treated individuals in comparison to those receiving placebo (empty tablet) treatment and that continuing the program would have a very low likelihood of demonstrating any benefit from coenzyme Q10 usage in delaying the progression of early PD. 

For this reason, the Data Safety Monitoring Board of the program recommended stopping the study. Individuals currently enrolled in the program have been notified and the study sites are in the process of meeting with all participants. 

For the PD community, both scientists and people with Parkinson’s and their care partners, this outcome is disappointing. In an earlier, far smaller study, there was preliminary evidence that people taking CoQ10 at 1200 mg/daily appeared to slow disease progression. For this reason, the current study focused on the effects of CoQ10 at 1200 and 2400 mg daily. The study involved the participation of 600 individuals with early Parkinson’s in 67 North American study centers. To date, there were no reported safety concerns related to CoQ10 at dosages of 1200 mg/day and 2400 mg/day for up to 16 months of treatment.

Christopher G. Goetz, M.D., Chair of the PDF Medical Policy Subcommittee comments: 

“While a final judgment on the efficacy of CoQ10 must await full analysis of the data and peer review, PDF trusts the conclusion of the study sponsors that there is no evidence that CoQ10 reduces the progression of Parkinson’s disease. The action taken on May 27 shows the vigilance of NINDS and PSG in assuring that individuals in the study are kept well informed throughout the duration of a study, and are advised immediately in the event that an investigative treatment is found to have little likelihood of success.

“People with PD who are receiving CoQ10, and who feel they have been substantially helped while taking this over-the-counter product, may wish to discuss with their physician whether the group results should lead them to stop CoQ10 treatment or to continue treatment because of their individual response.

“Fortunately, there are several new and on-going programs that are studying the same question of whether early treatment of PD can positively delay clinical decline. These agents work differently from CoQ10 and they offer individuals in the current CoQ10 program – as well as other people with early PD – key opportunities for potential enrollment to continue our quest to delay the clinical decline of PD.”     

View both the announcement by NINDS and the statement by the Parkinson Study Group about the closure of the Co-enzyme Q10 study.

For information on Parkinson's clinical trials that are currently enrolling individuals, visit