Certified Neuroscience Registered Nurse (CNRN) Practice Exam

Which neurological condition is characterized by a decreased life expectancy if untreated?

1. Multiple sclerosis

2. Alzheimer's disease

3. Amyotrophic lateral sclerosis

4. Parkinson's disease

The correct answer is: Amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder that primarily affects motor neurons, leading to muscle weakness, atrophy, and eventually paralysis. One of the critical aspects of ALS is that, if left untreated, the progression of the disease significantly shortens life expectancy. Most individuals diagnosed with ALS experience a rapid decline in muscle function, which can lead to respiratory failure and other complications within a few years after diagnosis. In contrast, while conditions like multiple sclerosis, Alzheimer's disease, and Parkinson's disease can lead to notable morbidity, they typically do not have the same straightforward relationship to decreased life expectancy as observed in ALS. Multiple sclerosis is highly variable, with some patients living full lives with minimal disability. Alzheimer's disease generally has a longer progression, often allowing years before significant decline, and while it can lead to mortality, the process is often prolonged. Parkinson's disease can also be managed effectively for a considerable period, allowing patients to maintain a relatively stable life expectancy. Thus, ALS's rapid progression and direct impact on the vital functions of the body uniquely position it in this context as a neurological condition linked to decreased life expectancy when untreated.