First it would be good to know if you have genetic predisposition. I think mosts comercial DNA tests available test for APOE4 variations.

Second I would read on the research of Dr. Dale Bredesen. He has been studying how to map all the underlying factors that can lead to Alzheimer and how to test/treat markers that are associated with the disease.

According to him Alzheimer's disease is like a roof full of holes. You need to test and treat each individual hole to make sure it's not leaking.