Yes, it exists and is very similar to human dementia. Your dog seems to be showing typical symptoms I'm sad to say. It's no more curable than human dementia. The only good part is that the victims don't really know they have it. Their friends and family are the ones who suffer.

“In a time of deceit telling the truth is a revolutionary act.”
― George Orwell

It's not over when you lose. It's over when you quit.