Web Paper 1 - Lou Gehrig's Disease.
I wasn't sure what to think when my sociology teacher told our class last year that she had Lou Gehrig's disease and probably wouldn't be finishing the semester with us. She had been my teacher for World History during sophomore year, and I had been excited to have her again for another class because she was very passionate about her subjects. "Lou Gehrig's disease" meant nothing to me, and her nebulous explanation didn't help. Why did she have it? What was it? If she'd just found out that she had it, how did she know already that she wasn't going to finish the semester?
Lou Gehrig's disease is another name for a neurodegenerative disease called amyotrophic lateral sclerosis (ALS); it is often referred to as Lou Gehrig's disease after its most famous victim, Yankees baseball player Lou Gehrig. (1) ALS causes voluntary motor neurons (the nerve cells that control muscle movement) to die, preventing the brain from transmitting its signals to those muscles. Without signals ordering them to move, the muscles become unusable and eventually wither away, a process called atrophy. In the final stages of ALS, the muscles that control the diaphragm are also paralyzed, leaving patients unable to breathe on their own. Respiratory failure is usually the cause of death for people with ALS. (2)
The scariest thing about ALS is that nobody knows what causes it. There are guesses about some types of it: familial ALS has been linked to have genetic origins, and Guamian ALS seems to be influenced by a particular dietary neurotoxin. (3) However, the most common type, sporadic ALS, occurs across age, gender, and race boundaries with no immediately obvious cause, and is responsible for 90-95% of all ALS cases. (2) While sporadic ALS occurs 20% more frequently in men and usually appears in middle age,(2) there seems to be no single biological trait that characterizes most people who get ALS. Scientists "suspect" many possibilities, including "viruses, neurotoxins (especially in Guamanian ALS), heavy metals, DNA defects (especially in familial ALS), immune system abnormalities, and enzyme abnormalities," (3) but at the end of the day, no one really knows what causes ALS. It just happens.
Because scientists do not yet know what causes ALS, there are no effective treatments for it. The average lifespan for someone with ALS is 3-5 years after diagnosis, though about 10% live beyond 10 years. (4) Additionally, everyone who is diagnosed with ALS has his or her own quality of life and experience, because there is no order about which muscles begin to be affected when.
Although I initially sought to find out what might influence or increase the risk of ALS, I found very little on the topic - which surprised me, because 5,600 new cases of ALS occur in the U.S. every year, and roughly 30,000 people have the disease at any given time. (2) What I did find was conflicting official opinions about ALS's effects on the brain. According to the ASL Association, "for the vast majority of people, their minds remain unaffected" (2) during the progression of ALS, and the National Institute of Neurological Disorder and Stroke states that "a small percentage of patients may experience problems with memory or decision-making." (3) These claims stand in stark contrast to an article linked at Doctor's Guide, which describes a study that found "about one-third [of studied patients with ALS] showed evidence of cognitive impairment." (5) The study, published in the March 2006 issue of the Archive of Neurology, also said that 23% of the studied patients met the diagnostic criteria for dementia, (5) though dementia was described as being a very low risk by other ALS resources. (3) Furthermore, the authors of the study felt that more tests would probably show an even higher rate of dementia than initially reported, and that "free recall, executive function and naming were most impaired in ALS patients with dementia." (5) The idea that ALS can affect the brain as well has the potential to change how it is researched - and therefore, how treatments are designed.
Currently, the only treatment for ALS is the FDA-approved drug riluzole, which is "believed to reduce damage to motor neurons" (3) and extend patients' lifespan by a few months. However, researchers at the University of California in San Diego have created an experimental "molecular therapy" that injects antisense oligonucleotides (which slow the pogression of ALS) into the cerebrospinal fluid, thereby getting them through the blood-brain barrier. (6) The study, published in the August 2006 issue of Journal of Clinical Investigation, found that when such treatment was delivered, the body produced "far less of a protein that causes a hereditable form of amyotrophic lateral sclerosis." Although this treatment targets familial and not sporadic ALS, the technique shows promise for treating not other neurodegenerative diseases such as Alzheimer's, Parkinson's and Huntington's. (6)
There is one more clue in the hunt for ALS's cause and cure: research on silencing the mutant SOD1 gene in familial ALS has revealed that "limiting mutant damage to microglia robustly slowed the disease's course, even when all motor neurons were expressing high levels of a SOD1 mutant" - which means that what causes ALS and what keeps it going could be two seperate things. When surrounding non-nerve cells had the SOD1 gene silenced, the disease still occured, but progressed much slower. (6) This discovery might someday greatly lengthen the lifespans of patients with ALS.
I wish I had found more answers in my research about ALS; I don't like to be told that wonderful people like my sociology teacher randomly get diseases with no percievable cause or cure. However, I am optimistic about the future of ALS treatment because of these recent discoveries, and hope that molecular therapy will improve the lives of all of those currently affected by this mysterious and deadly disease.
(1) Wikipedia, the Free Encyclopedia: article, "Lou Gehrig." http://en.wikipedia.org/wiki/Lou_Gehrig
(2) ALS Association: http://www.alsa.org/als/what.cfm?CFID=2754458&CFTOKEN=37037096
(3) Neurology Channel: http://www.neurologychannel.com/als/
(4) National Institute of Neurological Disorders and Stroke: http://www.ninds.nih.gov/disorders/amyotrophiclateralsclerosis/amyotrophiclateralsclerosis.htm
(5) Doctor's Guide, archived article: http://www.docguide.com/news/content.nsf/News/852571020057CCF68525713400593A8C?OpenDocument&id=48dde4a73e09a969852568880078c249
(6) Doctor's Guide, archived article: http://www.docguide.com/news/content.nsf/News/852571020057CCF6852571B90049249E?OpenDocument&id=48dde4a73e09a969852568880078c249