Alzheimer

The most common cause is Alzheimer's disease. Dementia due to Alzheimer's disease is the most
common type of dementia and accounts for 55 to 80 percent of all dementias. Alzheimer's demeforentias typically begin with mild memory loss, but as the disease progresses, the memory loss and disorientation quickly become profound. About two-thirds of alzheimer's patients show psychiatric symptoms, including agitation, irritability, apathy, and dysphoria. As the disease worsens, people may become violent and experience hallucinations and delusions.

The disease usually begins after the age of 65, but there is an early onset type of Alzheimer's disease that tends to progress more quickly than the late-onset type, which develops after age 65. On average, people with this disease die within 8 to 10 years of its diagnosis, usually as a result of physical decline or independent diseases common in old age, such as heart disease.