This rare condition occurs when certain nerve cells die. These are the motor neurons that run from the brain to the muscles and control the muscles’ movements. The affected muscles cannot be stimulated and used, and they gradually waste away. The affected part of the body becomes increasingly weak. The disease can cause difficulty in swallowing, breathing, walking, or any other muscle powered activity. Thus it can interfere with virtually any of the body’s physical functions.Motor neuron disease occurs most often in people over 40. Little is known about its cause, and it cannot be cured. Treatment is directed at easing symptoms and helping you to remain relatively mobile and independent. In most cases death occurs within two to ten years of the onset of the disease.

Senile dementia is primarily a disorder of the elderly. Pre-senile dementia, or Alzheimer’s disease, is either the same or a similar disorder that occurs in someone under 60. It may be due to an underlying disorder such as hypothyroidism or a brain tumor , and in such cases it can sometimes be successfully treated if the cause is discovered in time. If this is not the case, it may be due to a progressive loss of brain cells, the cause of which is not known. Reasoning powers, memory, and other thought processes tend to deteriorate more quickly than they do in senile dementia, and the disease in a comparatively young person can be fatal within about five years.