What causes ALS?

Amyotrophic Lateral Sclerosis (ALS) is a scientific mystery. Despite the extensive research, the definitive cause of the disorder remains hidden, navigating scientists into further exploration. However, researchers have proposed some theories as to the origin of ALS. 

Hereditary Factor

One of the hypotheses on the etiology of ALS is a genetic predisposition, however, the correlation between genetic predisposition and ALS diagnosis is not clear.

Familial ALS

• Prevalence: Approximately 5-10% of ALS patients have a familial link.
• Inheritance Patterns: ALS can exhibit both autosomal dominant and recessive inheritance patterns.
• Genetic Mutations: Additionally, extensive DNA research has determined the possible involvement of mutations occurring in genes such as SOD1, C9orf72, and FUS.

Sporadic ALS

On the other hand, about 90-95% of cases are defined as sporadic – developed with no clear genetic factors or connections, opposing the hypotheses that ALS has a hereditary pattern.

What Causes ALS Disease: Environmental Factors

Certain environmental elements and past experiences have also been researched in relation to ALS.

• Toxin Exposure: Research has shown that exposure to specific pesticides and heavy metals can make the individual more vulnerable to developing ALS, especially if the individual has suffered from prolonged exposure to such toxins.
• Head Trauma: A particular focus has been directed towards the correlation between repetitive head traumas and ALS, especially in the diagnosis of late-onset ALS.

Cellular and Molecular Mechanisms

• Overproduction of Glutamate: Glutamate is an amino acid necessary for the body’s nervous system. However, excessive glutamate has been shown to damage and even destroy neurons.
• Dysfunction Of Mitochondria: Mitochondria has a role as a cellular powerhouse, therefore directly affecting the cell’s energy supplies. Dysfunctioning mitochondria can cause the cell to undergo a process called apoptosis, also known as cell suicide, consequently leading to premature cell death, and weakening the muscular and neural connections.
• Immune System Deregulation: The malfunction of the immune system causes the body to attack and destroy its own cells. This is called autoimmunity.

In conclusion, ALS researchers have conducted several studies determining the etiology of the condition. While the cause is still undefined, the research has allowed us to understand the probable origins and apply the proper treatment.

Credits:
Genetic Link to ALS
Ghasemi M, Brown RH Jr.: Genetics of Amyotrophic Lateral Sclerosis. 
Familial ALS: Inheritance Patterns
The ALS Association: Environmental Factors
Robert H. Shmerling, MD: Can ALS be caused by traumatic brain injury?
Foran E, Trotti D. Glutamate transporters and the excitotoxic path to motor neuron degeneration in amyotrophic lateral sclerosis.
Muyderman H, Chen T. Mitochondrial dysfunction in amyotrophic lateral sclerosis - a valid pharmacological target?