Induction of a Neurological Disorder by Cycasin in Mice

Abstract

SINCE an unusually high incidence of amyotrophic lateral sclerosis, a neurological disease, was found on the island of Guam by Kurland and Mulder¹, the search for the cause of the disease has been focused on Cycas circinalis, which the Guamanians have long utilized as a source of food starch. Ingestion of cycad plant material in the tropics and subtropics where cycads are indigenous has been reported to cause posterior weakness and ataxia, with a characteristic “goose-stepping” gait in cattle². Numerous feeding experiments have been conducted to evaluate the disputed conditions in which cycad paralysis occurs, but one cannot be sure that the test animals were not exposed to other risks which could produce locomotor difficulties, except for the experiments which were carried out in controlled conditions. Recently, Anderson and Hall³ reported that cattle which had been fed fresh cycad leaves showed a slight lack of co-ordination in the hindquarters which resulted in a swaying gait. None of the glycosides which are contained in cycads, however, has been shown, to be responsible for producing such neurological disorders.