The study, published in JAMA, and led by neurologists at Weill Cornell Medical College, found that use of Coenzyme Q10 (CoQ10) showed no evidence of clinical benefit in 600 patients participating in 67 centers in the United States and Canada.
“The negative findings are disappointing — and surprising — given that CoQ10 showed promise in the preceding Phase II study as well as in preclinical studies,” says Dr. M. Flint Beal, a professor of neurology and neuroscience at Weill Cornell Medical College. Dr. Beal is the study’s senior investigator.
The need for an agent to guard against development of Parkinson’s is greatly needed, he adds. The disease affects up to 4.6 million people worldwide, and its prevalence is predicted to more than double by 2030.
Given that strong evidence has emerged that dysfunction in the neuron’s power plant, the mitochondria, and the oxidative stress that results play a key role in the development of Parkinson’s, the researchers studied CoQ10. They theorized that CoQ10 might supplement the energy lost by dysfunctional dopamine neurons that ordinarily help control movement.
CoQ10 generates energy in the form of ATP — the same form produced in the mitochondria — and organs such as the heart and liver that have high energy needs have significantly greater quantities of CoQ10 in their cells compared to other body cells. CoQ10 has become a popular over-the-counter supplement and is even found in some body lotions.
The phase II study tested the effects of increasing doses of CoQ10 (300, 600, and 1200 milligrams daily) versus use of placebo. All patients also used 1,200 IU of vitamin E each day. In that study, 80 participants were studied for 16 months or until they required traditional therapy, which involves replacing dopamine that is lost when neurons die. The results suggested a possible disease-modifying effect, especially at the highest dose, Dr. Beal says.
The phase III study examined doses of 1,200 and 2,400 milligrams daily for the same time period, along with vitamin E, but while the treatment was safe and well tolerated by participants, CoQ10 was found to be ineffective.
The results do not mean that Parkinson’s disease is not a mitochondrial disease, Dr. Beal says. And he says that there are a number of other promising drugs targeting the mitochondria that could be tested.
But he added that it is important to be able to test a neuroprotectant that prevents nerve cells from degrading as early as possible in Parkinson’s disease. By the time most patients are diagnosed with the disorder, as much as 50 percent of their brain’s dopaminergic neurons have been lost, and the fate of the rest may already have been determined.
“The optimal time to initiate a disease-modifying therapy may be before the onset of motor symptoms,” Dr. Beal says.
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