Aging & the nervous system

There are 3 major neurodegenerative disorders: amyotrophic lateral sclerosis (ALS - Lou Gehrig's disease), Parkinson's disease, and Alzheimer's disease. These disorders appear to be related to the aging nervous system. At present, the only clearly recognized risk factor for all three conditions is increasing age. With increasing longevity of the population, they will become more common.

Even though the features of the neurodegenerative disorders appear quite different, there are similarities regarding the way in which the different parts of the nervous system degenerate. Most likely, a cure for one will result in great benefits for the others.

What are the features of neurodegenerative disorders?

Amyotrophic lateral sclerosis (ALS)

• muscle wasting
• weakness of arms, face, tongue, chest wall muscles (due to loss of neurons in one part of the brain - the cortex), and the spine
• vision, bladder and bowel functions, and thought processes are usually not affected

Death usually occurs within 3 to 4 years after symptoms appear.

Parkinson's disease

• tremor and stiffness
• difficulty with arm and leg movement and speech, mainly due to loss of neurons in one part of the brain (the basal ganglia)
• thought processes are usually affected

The disease often lasts more than 10 years, ending in death.

Alzheimer's disease

• impaired memory and thought process
• difficulty with movement and walking may eventually occur
• seizures may occur

The disease lasts about 8 years, ending in death.

The cause of neurodegenerative disorders

The cause of these disorders is unknown. As a result, no treatments, as yet, have been shown to significantly postpone the onset of these illnesses, nor slow down their progression. Many researchers think that there are probably several factors, likely environmental, that trigger the onset of these diseases. It is thought that a series of biochemical events then occur in the body, due to the aging nerve cells (neurons), that results in the recognizable features of disease. Once the genetics of these mechanisms are understood, it may become possible to control them through gene therapy.