ABSTRACT
Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease, is the most common motor neuron disease. The pathologic hallmark of ALS is the selective death of motor neurons in the brain and spinal cord that innervate skeletal muscles, with symptoms of progressive weakness, muscle wasting and spasticity. Genetic susceptibility is an important determinant of the risk for ALS. The rapid rise and subsequent fall of ALS incidence rates in the Western Pacific suggest that the cause may be an environmental agent that peaked after World War II and has declined, but not completely disappeared. The classic example of a neurodegenerative disorder caused by an environmental excitotoxin is lathyrism, a disease of upper motor neurons caused by excessive consumption of the chickling pea which contains an unusual amino acid that acts as a glutamate-like excitotoxin. The epidemiologic study of ALS and motor neuron diseases has spanned several recent decades and has undergone evolution over this time period.
