One of the problems we have with Alz drugs is that

One of the problems we have with Alz drugs is that we don't really know what the disease is. Sometimes people are diagnosed with Alzheimers and then it turns out that they have some other problem -- like thyroid, or tumor, or pressure on the brain which can be relieved with a stent.

There are various companies working on blood tests to try to diagnose Alzheimer's. Until there is a test that can detect it in living people, we're going to see drugs not appear to have the efficacy that they really do, because they're treating people for Alzheimer's when that person is suffering from some other syndrome.

So much we don't know, and so much time, money, and heartbreak wasted on the amyloid-theory drugs.