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December 27, 1971

Psychiatric Side Effects of Levodopa in Man

Author Affiliations

From the Section on Psychiatry, Laboratory of Clinical Science, National Institute of Mental Health, Bethesda, Md.

JAMA. 1971;218(13):1915-1920. doi:10.1001/jama.1971.03190260031009

Levodopa is the amino acid precursor of the cathecholamines, dopamine and norepinephrine. Along with serotonin, these catecholamines serve as neurotransmitters in areas of the brain related to psychomotor, vegetative, and emotional functions; thus, it is not surprising that the administration of levodopa is associated with mental changes. The documentation and quantification of these mental effects is particularly important because of the potential for increasing our basic understanding of the relationship between brain amines (particularly dopamine) and psychological states both normal and abnormal. When administered to animals, levodopa has been shown to produce a variety of behavioral effects depending to some extent on the dose and species employed; in general, high doses of levodopa produce alerting, motor activation and increased aggressiveness. These studies have recently been the subject of extensive reviews.1,2

The rationale for the use of levodopa in Parkinsonism is based on evidence that a dopamine deficiency exists in