My uncle has started to talk to himself a lot it is like he is having a full blown conversation. He will sit there muttering & waving his finger up in the air like he is responding to someone, meanwhile there is no one in the room. His daughter has caught him doing this a few times. She is worried it normally happens when he is alone in the room. He is in his 80's had a minor stroke about 6 years ago, is mobile, can walk & get around the house slowly. Any idea on what this could be?She is yet to make a doctor apt for him.