Amyotrophic Lateral Sclerosis: a rare disease, that advances quickly

ALS, is also called Charcot disease, after the French neurologist who described it, or Lou Gehrig's disease, after a famous baseball player. It is rare and fast, possibly leading quickly to death.

Motor neurons at the epicentre

This disease, also known as Lou Gehrig's disease, after a famous baseball player, is neurodegenerative. It affects the motor neurons responsible for sending information and movement orders from the brain to the muscles. The muscles gradually atrophy as they are less and less used, resulting in the progressive paralysis of the patient. This generally concerns the muscles of the legs, arms and hands, but also the muscles for swallowing and speaking, and the respiratory muscles, leading to respiratory problems after 3 to 5 years of evolution, often being the cause of death for patients. Nevertheless, intellectual and sensory functions remain mostly intact.

Two main clinical onset types

One type is the so-called "spinal" form, beginning in the extremities of the limbs. The second types is referred to as the so-called "bulbar" form, beginning in the bulbar innervation territories (swallowing, phonation and tongue motor control). It affects any person of any ethnicity, men slightly more than women (1.5 to 1) and generally starts around the age of 60 (between 40 and 70).

As of 2022, the US Food and Drug administration has approved three drugs for the treatment of ALS. These include riluzole, edaravone, and most recently sodium phenylbutyrate + taurursodiol (also known as Relyvrio). To date these drugs help the treatment and slowing down the evolution of ALS and its symptoms.

Several streams of research have been set up, notably thanks to the money raised specially since 2014 by the Ice Bucket Challenge, a digital social-media-focused fundraising viral strategy that had its peak during the summer of 2014. This made it possible to raise awareness of the disease, which had been largely unknown to the public. The concept? Spilling a large bucket of ice water on your head, causing a tetanizing (tensed) effect that is supposed to reproduce the muscle atrophy characteristic of the disease.

Researchers noted in 1993 that mutations in the gene that produces the enzyme SOD1 have been associated with hereditary cases of Charcot disease. Studies have also shown that patients have much higher levels of glutamate in serum and spinal fluid than normal. Glutamate, one of the brain's chemical messengers or neurotransmitters, kills neurons when they are exposed to it for too long.

Other scientists theorise that antibodies can directly or indirectly impair the function of motor neurons, interfering with the transmission of signals between the brain and muscles.