Common Diet Drug Shows Promise for Parkinson’s

Thanks to a small but carefully controlled study, researchers are expressing hope for the use of an over-the-counter diet supplement to slow the early development of symptoms of Parkinson’s disease (PD).

The substance is called Coenzyme Q10. It is easily available at drugstores across the United States.

Despite the favorable results of the small study, doctors warn that patients already taking medications for PD should not take Coenzyme Q10 without checking carefully with their own physicians. The interaction between the diet supplement and pharmaceuticals commonly prescribed for PD is unpredictable.

The 16-month study was conducted under the general direction of Clifford W. Shults, M.D., of the University of California at San Diego. The 80 participants were enrolled at 10 medical centers throughout the United States, including Weill Cornell Medical College in New York City, recipient of a center grant from the Parkinson’s Disease Foundation (PDF). The scientific advisory committee of the project was headed by Christopher Goetz, M.D., head of the movement disorder center at Rush Presbyterian-St. Luke’s Medical Center in Chicago, another recipient of a PDF center grant. The project was sponsored by the National Institute of Neurological Diseases and Stoke (NINDS).

The study design was very simple. The participants were picked from individuals diagnosed with PD, but with symptoms too mild to require levodopa or other prescription pharmaceuticals. After screening, they were divided into four groups on a “double blind” basis (with neither the participant nor the doctor aware of which patient was in which group). One group was assigned to take a small dose — 300 milligrams per day (mg/d) — of Coenzyme Q10. The second and third groups were assigned to take somewhat larger doses — 600 mg/d and 1200 mg/d. The fourth group received a placebo — a pill resembling Coenzyme Q10 but containing none of the substance.

At the end of 16 months of treatment, patients taking 1,200 mg daily of Coenzyme Q10 were significantly better than patients taking placebo, as based on a standard rating scale for measuring PD. Patients in the 300 mg/d and 600 mg/d groups were also better than those in the placebo group, but the difference was not statistically significant. The authors interpreted this result as showing that Coenzyme Q10, taken at 1,200 mg/d, can slow the progression of early PD.

Why Coenzyme Q10 helped the PD patients in this study is not clear. The drug plays a role in cell energy production, and perhaps can boost brain cell function in PD. This idea is, however, speculative, and needs further study. It is possible that Coenzyme Q10 interacts with PD medications, or has some other direct effect on PD symptoms unrelated to slowing disease progression. In this study, it was noted, Coenzyme Q10 did not prevent or delay the need for antiparkinson medication any better than placebo. Also, when using a timed tapping device to assess hand function, patients taking Coenzyme Q10 performed no differently than those taking placebo.

Coenzyme Q10 is well tolerated and safe. The major drawback to its use is the expense, estimated at $1,500 to $2,500 a year. This vitamin is an over-the-counter drug, and is not covered by medication plans. The result of this study is promising but further research, involving larger numbers of patients, is needed before Coenzyme Q10 can be recommended as a standard agent for PD.

In the words of Dr. Schults, “This study hasn’t yet proven unequivocally that it will slow the progression of PD. Coenzyme Q10 is not inexpensive, and I don’t recommend that people spend $1,500 to $2,500 a year on a compound that may eventually turn out to be not effective.”