Melatonin and Parkinsonism

To the Editor.— Lerner discovered melatonin (N-Acetyl-5-methoxytryptamine)1and showed that this pineal hormone can induce sedation in man.2This agent antagonizes the darkening of the skin and, therefore, perhaps also some other action of melanophore-stimulating hormone (βMSH).3Since injections of βMSH had aggravated the tremor of parkinsonism,4we had administered this antagonist of βMSH to a patient but induced only a diminution of tremor.3Others, however, reported impressive improvement of several symptoms of parkinsonism5at a time when we had reversed the adventitious movements caused by levodopa [3-(3, 4-dihydroxyphenyl)-L-alanine] with melatonin in experimental animals.6We conducted therefore a single-blind study in patients with parkinsonism who received either melatonin alone or melatonin plus levodopa, which had caused intermittent adventitious movements.7 The inpatients listed in the Table and all of the outpatients had idiopathic parkinsonism except patient 11 who had postencephalitic disease. Among