Parkinson's disease is a neurological disease affecting the "substantia nigra," a small area of cells in the mid-brain. Degeneration of these cells as a result of free radical activity results in a reduction in levels of the neurotransmitter dopamine and upsets the balance between dopamine and another brain chemical, acetylcholine. The most familiar signs of the disease are tremor, or trembling in hands, arms, legs, jaw, and face; a generalized slowness of movement, stiff limbs, rigid facial expressions, and problems with balance or gait. Depression often precedes the physical signs, and mental function can deteriorate in advanced cases.
There's no cure for Parkinson's, but progression can be slowed and symptoms managed with a variety of drugs including L-Dopa (Levodopa) and Sinemet (Carbidopa). L-Dopa is converted to dopamine in the brain. Sinemet prevents L-Dopa from being broken down before it reaches the brain.
Glutathione is an antioxidant and free-radical scavenger found in the brain. In Parkinson's disease, glutathione levels are reduced in dopamine neurons (brain cells containing dopamine). Some studies have shown that administering glutathione intravenously can help improve symptoms in Parkinson's patients. Theoretically, glutathione limits the action of free radicals.
The physician who has directed the most research on this is David Perlmutter, M.D., a neurologist in Florida. I checked with him after receiving your question and learned that he has completed a double-blinded, placebo controlled study to be published later this year in a peer-reviewed medical journal. While he cannot discuss the clinical data prior to publication, Dr. Perlmutter indicated that his findings demonstrate glutathione administration was "quite effective" in treating the Parkinson's patients who participated in the study.
In an interview in 2008, Dr. Perlmutter was quoted as saying that 80 to 90 percent of Parkinson's patients treated with glutathione improve dramatically. He said that while glutathione doesn't raise dopamine levels, it allows dopamine in the brain to become more effective. He also noted that glutathione can increase sensitivity to the neurotransmitter serotonin, which may explain why many of his depressed PD patients improve so markedly. Dr. Perlmutter reported that he has been treating Parkinson's patients with glutathione for three years, administering it as a 10-minute, intravenous (IV) infusion three times a week. Dr. Perlmutter explained that glutathione must be given IV; given orally, it breaks down very rapidly. He said that in some cases, patients improved so dramatically that the dosage of the medications they take for the disease could be reduced.
We'll know more after Dr. Perlmutter's study is published. I'll update my Web site when the new information is available.
Andrew Weil, M.D.