L-tryptophan in the treatment of levodopa induced psychiatric disorders

Abstract

Nine patients with levodopa induced psychiatric side effects were treated with L-Tryptophan in a single blind controlled study. In all patients levodopa therapy was continued and no sedative agents were given. In 8 patients all psychiatric side effects cleared within 48 hours, and without reoccurrence of these symptoms on an 8 month follow up. Only one patient did not respond to the treatment, but this patient proved to have a psychotic depression which was unrelated to levodopa therapy. Six patients with levodopa induced psychiatric disorders were used as control subjects and were not treated with L-Tryptophan. In these patients mental changes subsided only after levodopa had been discontinued for a period of 2 to 8 weeks. The rationale for treatment with L-Tryptophan is based on the findings of decreased serotonin content of the brain after levodopa treatment. This was documented by animal studies and reflected by changes in the spinal fluid concentration of 5-hydroxyindolacetic acid before and after L-Tryptophan treatment. This study confirms the results described by Dr. Birkmayer who treated levodopa induced psychosis first in 1972 in this manner.