The two faces of L-DOPA: benefits and adverse side effects in the treatment of Encephalitis lethargica, Parkinson's disease, multiple sclerosis and amyotrophic lateral sclerosis.

Parkinson's disease, encephalitis lethargica, multiple sclerosis and amyotrophic lateral sclerosis patients all display two distinct types of symptoms. Some of these are due directly to a deficiency of dopamine and are quickly reduced by laevodihydroxyphenylalanine (L-DOPA). The second set, however, are the result of neurological damage caused by metabolites of dopamine, which include dopachrome and other chrome indoles that are both hallucinogenic and neurotoxic. If this hypothesis is correct, three corollaries follow. Patients of all four disorders should display excessive oxidative stress, natural methyl acceptors should delay development and elevated antioxidant supplementation, given with L-DOPA, ought to prolong the "honeymoon" period in which the benefits of the drug out weigh its subsequent disadvantages. A literature review suggests that all three corollaries are probably correct.