CoQ10 May Slow Progression of Parkinson Disease

Laurie Barclay, MD

October 14, 2002

Oct. 15, 2002 — Coenzyme Q10 (CoQ10) appears to slow the progression of Parkinson disease (PD), according to the results of a multicenter, double-blind trial published in the Oct. 15 issue of Archives of Neurology.

"This trial suggested that CoQ10 can slow the rate of deterioration in PD," principal investigator Clifford Shults, MD, from the University of California, San Diego (UCSD) School of Medicine, says in a news release. "However, before the compound is used widely, the results need to be confirmed in a larger group of patients."

In the Parkinson Study Group national clinical trial, 80 patients with early disease not yet requiring anti-Parkinsonian medications were randomized to receive CoQ10, 300, 600 or 1200 mg/day, or placebo, four times daily. All patients also received vitamin E during the trial, but were not permitted to be on antioxidants within 60 days before the baseline period. Regular follow-up evaluations continued every four months until patients needed treatment with anti-Parkinsonian medications, or for a maximum of 16 months.

"CoQ10 plays a crucial role in normal mitochondrial function both as a component of the electron transport chain which makes cellular energy and as a molecule with antioxidant and pro-oxidant properties," says co-investigator Richard Haas, MD, also from UCSD. "Tissue CoQ10 levels fall with aging and we do not know why this occurs. The normal lower levels of CoQ10 in older individuals may be a contributing factor in the progression of some diseases of aging."

By the eighth month of the study, there was a dose-response pattern suggesting that CoQ10 slowed deterioration of cognitive function, mood, activities of daily living, and motor skills. The most dramatic effects were on activities of daily living, including feeding, dressing, bathing, and walking. Parkinson Disease Rating Scale scores reflecting impairments were lowest in the group receiving 1200 mg/day, highest in the placebo group, and intermediate in groups receiving 300 or 600 mg/day. Progressive deterioration in the high-dose CoQ10 group was 44% slower than in the placebo group.

Adverse effects in the CoQ10 groups were not significantly different than in the placebo group. Groups receiving CoQ10 had significant increases in blood levels of coenzyme Q10 and in mitochondrial oxidative metabolism.

Lack of effect during the first month of treatment followed by subsequent sustained effect suggests that the drug may have been slowing the underlying progression of the disease rather than just improving symptoms. However, the statistical power of the study may have been insufficient to detect an effect in the first month. The efficient phase II clinical trial design developed for this study should be applicable to other drugs that might slow the progression of PD.

"While it is tremendously encouraging that our results indicate that it is likely that CoQ10 slows the progression of PD, our study did not have sufficient numbers of patients to unequivocally prove that it does," Shults says, recommending additional larger trials with hundreds of patients. "It would be premature to recommend that patients with Parkinson's disease take high doses of CoQ10."

Shults is a co-inventor of the CoQ10 compound and has a pending patent application jointly owned by Enzymatic Therapy, Inc.

In an accompanying editorial, Roger N. Rosenberg, MD, from the University of Texas Southwestern Medical Center in Dallas, notes that these "intriguing and provocative therapeutic findings" support the role of mitochondrial dysfunction in the pathogenesis of PD. He recommends further studies with higher doses of CoQ10, which may "offer considerable potential hope for future allied therapies."

Arch Neurol. 2002;59:1523, 1541-1550

Reviewed by Gary D. Vogin, MD