What is the primary cause of amyotrophic lateral sclerosis (ALS)?

The primary cause of amyotrophic lateral sclerosis (ALS) is the degeneration of motor neurons. ALS is a progressive neurodegenerative disease that primarily affects the motor neurons in the brain and spinal cord, leading to muscle weakness and atrophy. As these motor neurons degenerate and die, the brain loses the ability to initiate and control muscle movement. This degeneration results in the characteristic symptoms of ALS, including muscle twitches (fasciculations), cramping, weakness, and eventually paralysis.

Understanding this mechanism is crucial, as it highlights the focus on motor neuron pathology in ALS rather than other causes or contributing factors. While other conditions, such as injury or inflammation, can affect the nervous system, they are not considered the primary underlying cause of ALS. This distinction is essential for both diagnosis and the development of targeted treatments for the disease.