Plant at the root of neural disorders.

Plant at the root of neural disorders

In the decade following World War II, neurological diseases became disturbingly common on the west Pacific islands of Guam and Rota. The prevalence of amyotrophic lateral sclerosis (ALS), or Lou Gehrig's disease, was up to 100 times higher among the Chamorro inhabitants of the islands than among the people living in developed countries. And the Chamorros suffered from parkinsonism and Alzheimer-type dementia too.

What caused the dramatic increase and then, after 1955, a steady decline in the incidence of neurological disorders on these islands has been the focus of some 40 years of study. In the July 31 SCIENCE, researchers at the Albert Einstein College of Medicine in Bronx, N.Y. and their French, British and German colleagues finger a possible culprit: an unusual amino acid found in the seeds of the false sago palm.

When the research team, led by Peter S. Spencer, fed macaques a synthesized version of this amino acid--betamethylamino-L-alanine (BMAA)--the monkeys developed nervous system abnormalities and behavioral changes reminiscent of ALS and parkinsonism in humans. The researchers believe that BMAA binds to neurons at sites where the neurotransmitters glutamate and aspartate normally attach and overstimulates the nerve cells, eventually causing them to die. They are currently searching for additional plant substances that may be neurotoxic.

Spencer's group suspected the palm seeds partly because the Chamorros used them extensively as food (rice was scarce) and as a topical medicine during the Japanese occupation of the islands between 1941 and 1944, but the seeds later fell out of favor. Also, no viral or genetic factors could be implicated.

"This is one of the first times that an environmental factor such as this plant has been shown to induce such [neurological] diseases,' says team member Richard C. Robertson. Previously, the team linked an amino acid in chickling peas (which are consumed in Africa and Asia, especially during famines) to a related neurological disorder called lathyrism. The environment, says Robertson, may have a hand in other cases of neurological diseases around the globe as well.