ALS and Neurodegenerative Disease

Written by Ren on Friday November 22, 2019

For much of history, diseases of the brain associated with aging were often thought to be natural progressions, much like grey hair and wrinkles. Senility has long been thought of as an expected reality for elderly populations. But this is not the case. Now that the medical community has more of an understanding of the mechanisms behind neurodegenerative disease, strides have been made to alleviate the suffering on behalf of patients and caregivers living with these diseases. However, of all neurodegenerative diseases described by modern medicine, amyotrophic lateral sclerosis--or ALS--perhaps has the least known about it. Physicians and family members alike are often at a loss when it comes to determining the best course of action for ALS patients.  

First, it might be helpful to lay out the groundwork for what a neurodegenerative disease is. Neurodegenerative diseases typically involve the gradual breakdown of neuronal networks in the brain, resulting in loss of both motor and mental function. Possible mechanisms behind disease progression include misfolded proteins that are able to multiply themselves and infect, much like a virus; abnormal peptide chain breakages, accumulated changes directly in the genetic code, and proteins that have degraded and become unreadable over time. In ALS specifically, a build-up of neurofilaments has been recorded in the surrounding cerebrospinal fluid that bathes degenerating motor neurons. Unfortunately, the role these neurofilaments are not yet known at this time

In the United States, nearly 10 percent of adults over age 65 will develop a neurodegenerative disease of some kind. Most of the time, this will be Alzheimer’s, Parkinson’s or Huntington’s disease. But rarely, they may develop amyotrophic lateral sclerosis, a debilitating and quick-progressing illness that affects the brain stem and spinal cord. Only about 20,000 people in the United States are living with ALS at any given time, or about 7 per 100,000 people. In most instances of the disease, the development is sporadic with no known instigating factor. But in 5 percent of ALS diagnoses, the disease will show key genetic markers that indicate that the disease was passed along a hereditary line. 

ALS can be a difficult disease to diagnose, too. There is no one indicative test that points to ALS presence, so a diagnosis is often made by first excluding other possible pathologies. Electromyography allows physicians to identify regions where there has been significant loss of motor neurons, which is the disease’s only real hallmark. Many of the earliest symptoms of ALS mimic a variety of other known conditions, including myasthenia gravis, Lyme, and heavy metal intoxication. Because it affects the corticospinal tract, the first ALS symptoms someone might notice include progressive muscle weakness in limbs or difficulty swallowing. In 15 percent of ALS patients, caregivers also note personality changes, sudden irritability, impulsivity, and memory problems associated with frontotemporal dementia.

Where the disease first begins to show symptoms can result in differing prognoses as well. Bulbar ALS begins in the brain stem and is generally more immediately worrying because it affects speech, swallowing, and the muscles controlling airways. ALS symptoms that begin in the limbs, on the other hand, will typically give the patient a longer life expectancy from the outset. Regardless, the outlook of an ALS diagnosis is not very hopeful. Patients will typically succumb to asphyxiation or respiratory failure within three years of an ALS diagnosis. 

As far as therapy goes for those living with progressive ALS, there are scant options. Riluzole is the only evidence-based medication currently on the market designed to modify the progression of ALS, and is able to effectively delay tracheostomy and ventilator-dependence. Other methods of providing support to ALS patients with advanced symptoms include the use of easy-to-swallow foods and beverages, suction machines to keep airways clear, non-invasive positive airway machines, and tracheostomy support.

Beyond the equipment designed to provide some relief for patients, counseling can be exceedingly helpful for sufferers, caregivers and family members alike. Caring for a loved one with a degenerative illness can take a huge emotional toll on the psyche, and having a strong support network combined with professional help can alleviate some of the burden. 

While there are no medications available today that can drastically alter the course of the disease progression, research efforts are focused on finding ways to combat the march of neurodegenerative agents. With a more complete understanding of signalling pathways, possible genetic factors, and disease developmental trajectory, we will likely be able to see huge leaps in ALS treatment in the future. 

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Sources:

Amyotrophic lateral sclerosis: https://www.sciencedirect.com/science/article/pii/S0140673610611567

Amyotrophic lateral sclerosis: https://link.springer.com/article/10.1186/1750-1172-4-3

The changing scene of amyotrophic lateral sclerosis: http://www.ta-als.org/wp-content/uploads/2013/04/nature_review_neuroscience_article.pdf

Amyotrophic lateral sclerosis: https://medicinainternaelsalvador.com/wp-content/uploads/2017/08/Amyotrophic-Lateral-Sclerosis.pdf

Controversies and priorities in amyotrophic lateral sclerosis: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4565161/

Clinical diagnosis and management of amyotrophic lateral sclerosis: https://bit.ly/2O6SdAA


Neurodegenerative Diseases and Prions: https://www.nejm.org/doi/full/10.1056/nejm200105173442006

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