Causes of Amyotrophic Lateral Sclerosis
Author: mzPOTTER
No known cause of ALS and scientists still do not know why some people attack and not others. A major step to answer this question came in 1993 when scientists supported by the National Institute of Neurological Disorders and Stroke (NINDS) found that mutations in the gene for SOD1 enzyme were associated with some cases of familial ALS.
This enzyme is a powerful antioxidant that protects the body from damage caused by free radicals. Free radicals are highly unstable molecules produced by cells during normal metabolism. If not neutralized, free radicals can accumulate and cause random damage to DNA and proteins in cells.
Although it is unclear how the SOD1 gene mutation leads to motor neuron degeneration, researchers have theorized that an accumulation of free radicals can result from malfunction of this gene. In support of this theory, studies in animals show that motor neuron degeneration and deficits in motor function accompany the presence of a mutation in SOD1.
Studies also have focused on the role of glutamate in the degeneration of motor neurons. Glutamate is one of the chemical messengers or neurotransmitters in the brain. Scientists have found that, compared with healthy people, ALS patients have higher levels of glutamate in the serum and cerebrospinal fluid (around the spinal cord). Laboratory studies have demonstrated that neurons begin to die when exposed for long periods to excessive amounts of glutamate. Now scientists are trying to understand what mechanisms lead to an unnecessary accumulation of glutamate in the cerebrospinal fluid and how this imbalance may contribute to the development of ALS
It has been suggested that autoimmune responses, which occur when the body’s immune system attacks normal cells-can be a cause of motor neuron degeneration in ALS. Some scientists theorize that antibodies may directly or indirectly damage the function of motor neurons, interfering with the transmission of signals between the brain and muscles.
In the search for the cause of ALS, researchers have also studied environmental factors such as exposure to toxic or infectious agents. Another study has examined the possible role of dietary deficiency or trauma. However, until now there is not enough evidence to implicate these factors as causes of ALS.
Future research may show that many factors, including genetic predisposition, may be involved in the development of ALS.