Causes of ALS

Amyotrophic Lateral Sclerosis (ALS), better known in the United States as Lou Gehrig's disease (after the famous baseball player who contracted the disease), is a degenerative disease that affects the motor neurons, causing the nervous system to degenerate.

Background

• There are three types of ALS. Sporadic ALS, the most typical, can manifest in any person. Familial ALS, which is genetically inherited, is less common. Guamanian ALS is a very specific instance of ALS that was rampant in Guam in the 1950s.

  Motor neurons allow the brain to control the movement of muscles via the nervous system. ALS causes these neurons to degenerate and die, thus preventing brain signals from reaching the muscles. Due to the decreased movement, the muscles atrophy.

  This lack of neural communication not only affects movement of the arms and legs, but also one's breathing and other voluntary muscle movements. ALS does not affect the muscles that control involuntary movements, such as heartbeat and digestion. It also does not affect the body's senses, nor does it very often affect eyes muscles, bladder or bowels.

Causes

• Familial ALS results from the presence of an inherited dominant gene for ALS. Otherwise, a seemingly healthy person can develop sporadic ALS at any time.

  The specific cause of ALS is unknown. However, there are theories. In a small percentage of cases, it is known that ALS is caused by mutation of the SOD1 gene, which produces an enzyme that serves as an antioxidant to neutralize the dangerous free radicals that cells normally produce. It is unknown how the mutation results in the motor neuron damage, but this mutation accounts for one-fifth of familial ALS cases. One theory suggests that the gene mutation results in a buildup of free radicals.

  There is also an accumulation of the neurotransmitter glutamate in the spinal fluid of ALS patients. While it is known that frequent exposure to large amounts of glutamate lead to neuron death, it is unknown why this buildup occurs nor how it leads to ALS.

  There are other, less substantiated theories for the cause of ALS, as well, such as antibodies attacking the motor neurons or contact toxic materials.

Symptoms

• Often initial symptoms of ALS are minor and go ignored until the disease progresses. Early symptoms can include muscle weakness, difficulty swallowing or breathing, twitches and cramps in the extremities, difficulty in speech, and shortness of breath. Many of these symptoms are common for other diseases, thus making ALS notoriously difficult to diagnose. To complicate matters, different symptoms can manifest for different people.

  Most commonly, a patient will experience muscle weakness, often affecting everyday activities, such as lifting and movement. This weakness spreads until paralysis occurs.

Effects

• ALS does not affect a patient's mind, but can cause problems like depression and difficulty with memory and making decisions.

  As the body increasingly loses the ability to control muscles, the patient soon loses the ability to breathe once the diaphragm and chest wall muscles are lost. Patients then require an additional apparatus to breathe.

  Most ALS patients die from respiratory failure. The average life expectancy of a patient with ALS ranges between two and five years after diagnosis. However, some patients have lived beyond five years.

Treatments

• While there is no cure for ALS, some patients may look to riluzole, the first FDA-approved drug treatment for ALS. Riluzole decreases glutamate release in the nervous system and can prolong a patient's life by months. Scientists are currently looking towards stem cells and gene therapy for potential treatments for ALS.

  Otherwise, most care for ALS focuses on improving the patient's quality of life. By working with various professionals, such as therapists, physicians and nutritionists, the patient can attempt to achieve an acceptable level of comfort and mobility. Medication can reduce the effects of ALS in regards to cramps, fatigue, difficulty sleeping and other problems. Light exercise can help patients retain some mobility and keep working muscles and health in check.