From Golnar Fozi's First Day of School, an essay about her mother:

Three years ago, my mother was diagnosed with Alzheimer's Disease...Her neurologist, who lost his own mother to Alzheimer's Disease, explained it best. He said it is as if Alzheimer's Disease patients live in a parallel universe where time is meaningless and nothing makes such sense. Periodically, they stop at a window that gives into our world, and look through it. If we happen to be standing there at that same instant, then we establish a momentary contact before they walk away. The best those of us who love them can possibly hope for is that we are standing there when they look through the window. For a few seconds they see us there and know that we never left them.