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Ubiquinol and Parkinson's disease.

Thirty-one patients with Parkinson's disease who were experiencing the "on-off" phenomenon while receiving levodopa (Group 1), and 33 other patients with Parkinson's disease who were not being treated with levodopa (Group 2) were randomly assigned to receive, in double-blind fashion, 300 mg per day of ubiquinol (the reduced form of coenzyme Q10) or placebo for 48 weeks (Group 1) or 96 weeks (Group 2). Among the patients in Group 1, treatment with ubiquinol resulted in an improvement in mean symptom severity, as determined by the Unified Parkinson's Disease Rating Scale (p < 0.05 compared with the change in the placebo group). Among the patients in Group 2, symptoms worsened in both groups, with no significant difference between groups.

Comment: With prolonged use of levodopa, disabling side effects such as random daily motor fluctuations (known as the "on-off" phenomenon) and random drug-resistant "off" periods occur in a large proportion of patients with Parkinson's disease. These abnormalities are thought to be due to erratic delivery of levodopa to the brain, which may result from the fact that large neutral amino acids (phenylalanine, tyrosine, methionine, leucine, isoleucine, valine, and tryptophan) compete with levodopa for intestinal absorption and for transport across the blood-brain barrier. One group of investigators found that, if protein intake at breakfast and lunch was severely restricted (i.e., a total of no more than 7 g of protein until the evening meal), then daytime plasma concentrations of large neutral amino acids remained relatively low, and the "on-off" phenomenon was eliminated in many patients. Although symptoms typically returned after the high-protein evening meal, many patients were able to function almost normally during the day.

Preliminary research suggested that coenzyme Q10 can improve symptoms in patients with Parkinson's disease, but several large follow-up studies concluded that coenzyme Q10 was of little or no value. The new study suggests that ubiquinol (and, presumably, coenzyme Q10 as well) can improve symptoms in a subset of patients: those experiencing the difficult-to-treat "on-off" phenomenon. It is possible that treatment with ubiquinol or coenzyme Q10 would also allow these patients to liberalize their very restricted diet.

Yoritaka A et al. Randomized, double-blind, placebo-controlled pilot trial of reduced coenzyme Q10 for Parkinson's disease. Parkinsonism Relat Disord. 2015;21:911-916.

by Alan R. Gaby, MD

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Title Annotation:Literature Review & Commentary
Author:Gaby, Alan R.
Publication:Townsend Letter
Article Type:Report
Geographic Code:1USA
Date:Dec 1, 2015
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