Role of environmental toxins in Amyotrophic Lateral Sclerosis (ALS)

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease, characterized by degeneration of upper and lower motor neurons in the cerebral cortex, brainstem and spinal cord leading to progressive muscular weakness. The incidence of the disease worldwide has been reported from 0.3 to 2.5 cases per 100,000 persons per year with an estimated 2 cases per 100,000 population per year in Europe and the United States. More than 90% of these patients are sporadic in origin, and the lifetime risk of acquiring ALS by age 70 is between 1 in 400 to 1 in 1000. Despite extensive research, the etiology of this devastating disorder remains elusive. The underlying pathophysiologic mechanisms seem to involve a complex interaction of genetic and molecular pathways. Multiple other mechanisms possibly leading to disease have been considered over the years including viral infections, autoimmune basis, mitochondrial dysfunction, oxidative stress, axonal transport, protein folding and misfolding, and environmental toxins. After a brief review on the presentation, diagnosis and management, this chapter will focus primarily on the potential of environmental toxins in the development of ALS.