Amyotrophic Lateral Sclerosis (ALS) (cont.)
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What causes amyotrophic lateral sclerosis (ALS)?
We do not know exactly what causes ALS. Although some cases of ALS are hereditary (run in families), most are not. A mutation of a gene called SOD1 has been identified in some of the hereditary cases, but we do not know what role the mutation plays in the disease.
Using an evidence-based approach, smoking was found to be more likely than not a risk factor for ALS based on two excellent studies by Kamel et al. and Nelson et al. Smoking has a broad public health impact, no redeeming features, and is a modifiable risk factor. Evidence also supported the conclusion that the following were probably not risk factors for ALS: trauma, physical activity, residence in rural areas, and alcohol consumption.
What are the symptoms of amyotrophic lateral sclerosis?
ALS may begin as weakness, awkwardness, or atrophy in one or more limbs. It may start as a difficulty swallowing or speaking. The symptoms may be very subtle at first, and may be overlooked. Common symptoms include the following:
There may be evidence for frontal lobe dysfunction in patients with ALS. Usually, this dysfunction is subclinical (not readily apparent or causing symptoms) and it is detectable only when looked for specifically with focused tests. However, in a minority of patients, clinically significant cognitive impairment becomes evident, with a continuum of abnormalities extending all the way to frank frontotemporal dementia. In addition to difficulties in planning and sequencing (the most common manifestations of "executive dysfunction" due to frontal lobe disease) some patients may express an otherwise inexplicable nonchalance or lack of insight into their situation and its impact on themselves and their loved ones and others; fortunately rarely, they may become less friendly than their usual selves. These aspects of ALS, when present, may pose major challenges to caregivers and healthcare personnel alike, and they may be associated with shorter survival.
Depression and anxiety may occur in patients with ALS. Though difficult to prove, these are likely part of the disease process itself, rather than mere reactions of the patients to their condition. Depression and anxiety are treatable.
Finally, some patients with ALS frequently exhibit a so-called pseudobulbar affect, manifesting as involuntary, uncontrolled outbursts of crying or laughter, which is distinct from their underlying mood.
As the disease progresses, the person with ALS loses the ability to carry out everyday activities such as dressing, eating, and working. Eventually getting out of bed becomes impossible without assistance. The person becomes restricted to a wheelchair or bed (the development of bedsores can be a problem.) As the respiratory muscles weaken, breathing becomes more and more difficult. The risk of pneumonia increases.
Hereditary (familial SOD1) and nonhereditary (sporadic) cases of ALS may have similar symptoms and course, but in some forms of ALS these manifestations may be quite distinct (for instance, there are cases of familial ALS with juvenile onset).
Medically Reviewed by a Doctor on 6/16/2016
Fernando Dangond, MD
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