What makes alzheimer's difficult is that it is not really a single uniform disease. There are subtypes.
Since my mother has it, I was presented with an option of a genetic test. There are several genes which increase your risk. However, if one has PSEN1 that will 100% guarantee early onset alzheimer's at some point.
I'm still on the fence if I want to know.
I really hope we get some viable treatments for this terrible disease. Early onset azlheimer's is awful. I cannot imagine having malfunctioning brain.