Up over time, and when this happens, it sticks to itself and forms plaques. so you may have heard of am alloyd plaques. once it builds up to a tipping point, it will cause a bunch of molecular events in the brain that lead to the death of the you're r neurons. >> this tipping point is sort of more important than others sometimes? >> what's interesting about the tipping point is that you can have this -- the disease can be ongoing in your brain without you knowing for 10 to 20 years, we think. before the tipping point, you don't have symptoms of alzheimer's. once it hits the tipping point, i li...