
To be diagnosed with ALS, the patient must show symptoms of both upper and lower motor neuron degeneration that cannot be traced back to other causes.
ALS is notorious for differentiation in early symptoms. Some people may experience a sudden difficulty with swallowing, some may begin to fall, some others may experience a limited range in motion due to weakness in their arms or legs. Also, the rate at which the disease progresses varies among individual cases. The average survival time for those diagnosed with the disease is somewhere between three and five years, but some people survive for twenty or more years, and others only live for two or three. Only ten percent of victims survive past year five.
This disease causes muscle degeneration, but it does not affect sight, smell, taste, or the ability to hear. It also does not normally affect cognitive function. Some people describe the disease as a healthy brain in a dying body.

ALS seems to be a disease that will strike anyone at anytime, but most of the people that suffer from the disease are white males between the ages of 40 and 60. Ninety to 95% of all cases have unknown causes. Five to 10%, however are genetic diseases. Fifty percent of children with a parent who has familial ALS will also contract the disease. About 20% of these genetic cases invloves a mutation in the enzyme superoxide dismutase 1, which norishes the muscles. There are also very rare cases of juvenille onset ALS, which has no known/traceable cause.
In 1995, scientists discovered the cause for familial ALS. For an unknown reason, the gene that codes for the enzyme SOD1 are mutated and cannot produce the enzyme. This enzyme normally nourishes the muscle as an antioxidant when it destroys free radicals in the body. Although scientists discovered this gene mutation, they cannot figure out a link between the mutation and the disease. One theory is that the build up of free radicals around the muscles causes them to degenerate.
One theory is that glutamate, which is a chemical messenger in the brain, takes part in causing ALS. Patients who suffer from ALS normally have an elevated glutamate level in their spinal fluid. Once again, the link between this elevated level and the disease are unknown. Some scientists theorize that a buildup of glutamate raises the motor neurons' time of exposure to it, causing them to die off from overexposure.
Other theories include exposure to toxins or other environmental factors, or unknown genetic factors incluing anitbodies coded to attack motor neurons in the body. Research on this disease is ongoing, but it may be a long time before anyone can say for sure what causes this disease and why it affects the people it does.
There is no cure for ALS. The main focus of treatment is to adapt patients to their declining situation, and to make them comfortable when the pain becomes unbearable.