ALS is characterized by a degeneration of motor nerve cells in the brain and spinal cord, leading to muscle weakness. As the disease progresses, total paralysis and an inability to speak or swallow can result. For the vast majority of individuals, the mind and senses remain unaffected.
Epidemiology of ALS
No one knows what causes ALS. Researchers have been studying many factors that could be linked to it, such as heredity, environmental exposures, diet, and injury. We do know the following about ALS and its prevalence in the United States:
- ALS is estimated to affect some 18,000 people in the United States at any given time
- The annual incidence is about 2 per 100,000 people
- The annual prevalence is about 4 to 6 per 100,000 people
- The mean duration of the disease is approximately 3 years
- ALS is about 20 percent more common in males than in females
- Age at onset varies, but ALS is most often seen in people between 40 and 70 years old
- The prevalence of ALS in Massachusetts is not significantly different from estimates of the national average
Exposures to elements found in the environment, such as lead, mercury, and cyanobacteria, have been investigated for concerns in causing or increasing one’s risk in developing ALS. Studies finding an increased risk of ALS suggest that more research is needed to accurately assess causal links to any exposure.
For additional information about ALS, please visit The ALS Association.