Alzheimer's is a progressive degenerative disease that causes cognitive and memory impairment, as well as a variety of neuropsychiatric symptoms and behavioral changes that worsen over time. The causes of alzheimer's are still unknown, but researchers believe that for most people, Alzheimer's disease is caused by a combination of genetic, lifestyle and environmental factors that affect the brain over time.
Thus, there is a linear relationship between age and onset of alzheimer's, the older a person, the greater the chance of the disease to manifest. Usually the disease comes after age 75. The case of Sally's mother, who was diagnosed at a very young age at 50, gives evidence that her illness is manifested by genetic factors.
