It's a fairly well-documented phenomenon that people suffering from things like dimensia or alzheimers will behave inappropriately, in ways they wouldn't have earlier in life.

Whether they're expressing deep-seated beliefs or simply no longer able to filter invasive thoughts is hard to say. The brain is a complex system and damage caused by trauma or exposure to lead, for example, can also cause increased impulsiveness and social aggression.

I can't imagine how terrifying it must be to slowly lose control of your mind and 'self'.