AD typically begins with subtle and poorly recognized failure of memory. Slowly, over a period of years, the memory loss becomes more severe and eventually incapacitating. Other common symptoms include confusion, poor judgment, language disturbance, agitation, withdrawal, and hallucinations. Some patients may develop seizures, Parkinsonian features, increased muscle tone, myoclonus, incontinence, and mutism . Death usually results from general inanition, malnutrition, and pneumonia. The typical clinical duration of the disease is 8-10 years with a wide-range of 1-25 years.