• Levodopa or amantadine hydrochloride was administered to 25 patients with pathologic laughing and/or crying. This symptom was markedly improved in ten cases, most of which were devoid of a cortical atrophy or a periventricular lucency in computed tomographic scan and also devoid of a severe dementia or a disturbance in activity of daily living. The concentration of homovanillic acid in the CSF of the patients was significantly decreased, whereas the concentration of 5-hydroxyindoleacetic acid remained within the normal limit. Because part of pathologic laughing and crying seems to be caused by the decreased function of the dopaminergic neuron, levodopa or amantadine is worth trying.
Udaka F, Yamao S, Nagata H, Nakamura S, Kameyama M. Pathologic Laughing and Crying Treated With Levodopa. Arch Neurol. 1984;41(10):1095–1096. doi:10.1001/archneur.1984.04050210093023