Is it normal for a patient with dementia to stop watching television?

Yes, because they can no longer follow the story line or humor. Try some really old TV shows or movies from her era.

I found that my mother couldn't follow the stories anymore, of course this had been difficult for her anyway because of macular degeneration impairing her vision. But even the game shows that she used to enjoy like wheel of fortune and jeopardy are too quick for her now, and audio books are out too because she can't remember the story the next day.

My Dad will still watch some football/golf and the weather channel. Maybe some evening news. That's probably the reason why he never wanted to get cable TV as I had thought 5 years ago he and Mom would have loved Turner Classic Movies and Storm Chasers. Here I thought it was the cost, not realizing that maybe my parents no longer could follow a theme.

My Mom doesn't watch any TV at all, I don't think she even knows there is a TV set in her room at the nursing home.

My Dad was always a big sports fan but he can't follow the games any longer. He still likes the tv to be on but it's just background now.