Alzheimer's Disease - have any studies determined what causes it?

Scientists do not yet fully understand what causes AD. There probably is not one single cause, but several factors that affect each person differently. Age is the most important known risk factor for AD. The number of people with the disease doubles every 5 years beyond age 65.

Family history is another risk factor. Scientists believe that genetics may play a role in many AD cases. For example, early-onset familial AD, a rare form of AD that usually occurs between the ages of 30 and 60, is inherited. The more common form of AD is known as late-onset. It occurs later in life, and no obvious inheritance pattern is seen in most families. However, several risk factor genes may interact with each other and with non-genetic factors to cause the disease. The only risk factor gene identified so far for late-onset AD is a gene that makes one form of a protein called apolipoprotein E (ApoE). Everyone has ApoE, which helps carry cholesterol in the blood. Only about 15 percent of people have the form that increases the risk of AD. It is likely that other genes also may increase the risk of AD or protect against AD, but they remain to be discovered.

Alzheimer is one of the 8 known forms of Dementia. As far as I know, it is caused by shrinkage of the brain and mini strokes, which can be determined with a scan. there are 4 stages in dementia.
There are sites on the net which will explain in more depth.
Alzheimer's is the most commen form of dementia, like all forms can be treated to slow down the proses .
Alzheimer's is a battle between the personalities within. I believe it is caused by a dramatic change in life as also in Schizophrenia. My mom battle schizophrenia and Alzheimers is sorta the same I guess. They say though that two concious minds separates and produce various of activities. To learn more about this disease, I prefer a special research at a nearby hospital from a direct Professor or Doctor.