Alzheimer's Disease is a disorder involving deterioration in mental functions resulting from changes in brain tissue. This changes include shrinking of brain tissues not caused by disorders of the blood vessels (www.yahoo.com, 2000). This disorder is also known as primary generative dementia, diffuse brain atrophy and senile dementia.
             Senile dementia Alzheimer's type (SDAT) is the most common cause of intellectual decline with aging. The incidence is approximately nine out of ten thousand people and it affects women more often than men, occurring primarily in older people.
             The cause is unknown but several factors are believed to be involved in the development of the disorder although none have yet been proven. The neurochemical factors include lack of substances used by the nerve cells to transmit nerotransmitters, including acetylcholine, somatostatin and norepinephrine. Environmental factors include exposure to aluminum, manganese, and other substances. The infectious factors include virus like organisms called prion infections that affect the central nervous system. In some families (representing 5 to 10% of cases) there is an inherited predisposition to development of the disorder, but this does not follow strict patterns of inheritance. In able to make a diagnosis, other causes of dementia must be ruled out. The procedures vary but usually neuromuscular examinations, psychological tests and physiological exams such as CT scan and electroencephalogram are made.
             Researchers have found that in families that have multiple members with Alzheimer‘s, there is a particular gene variation which is common to all of those with the disease. The gene, which produces a substance called apolipoprotein E4, is not said to cause the disease but it's presence increases the chances that the disease may eventually occur. There are many people who have the E4 gene and never become afflicted with Alzheimer‘s.
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