There is a movie called The Curious Case of Benjamin Button. http://www.imdb.com/title/tt0421715/
Benjamin Button ages backwards. And that is sort of what vascular demnetia is like. But unlike the movie here it is, in my living room, in the man who used to be so funny, so on top of things.... a second degree black belt, with an amazing talent for playin bass guitar.
He hasn't lost too much yet, but he has lost enough to know there are problems - and it frustrates him immensely! I suspect some of the little strokes have been in his temporal regin because he is now very quick to snap at me and often is impulsive.
It must be overwhelmingly frustrating to be in his position. But now, whenever he snaps at me I know it is the strokes and not me.... and (for now, today) I can simply reflect back to him that it was inappropriate to snap, and that we are going to have a polite conversation. Usually that is enough to set things back to calmness.