It is really interesting that dementia patients can read, it boggles the mind, but even a lady I know with Picks disease will read closed captioning in the TV.
After each such a vascular event, a person suffering this kind of dementia often improves a bit, though not usually back to the level before that most recent event. Once a cognitive function is damaged in an Alzheimer’s patient, it’s seldom improves at all.
They can read til the very end. I would sit with my dad when he was really like an infant, and he’d love to look at a magazine with me. He would point at pictures of dogs or animals and smile. But he also pointed happily at ads that said “new a/c unit 30% off!” Dad always loved a sale.