" Right, so amyloid accumulates early and can be tracked on a PET scan 15-20 years before people develop symptoms. Tau comes later and is probably trigged by the presence of amyloid in the brain. Tau then can continue to spread and can track with visible symptoms. We believe that if its possible to interfere at the amyloid stage before tau is actually an issue, then you may have a real benefit on the disease progression. We have to understand that isn’t all amyloid but it is an important player. So if we target that we can dial down serious aspects of the disease. "