My dad is 91 years old. His new docotr doesn't beleive that he has dementia but says that thyroid disease could be causing his delusional disorder. We lost my mom a little over a year ago and, although my dad has always been a little paranoid, recently he beleives close friends want to harm him and he says a van has been following him. Last night he left the house in his pajamas and locked himself out. He said he was trying to get a number to car service just in case he needed it. Good thing a neighbor called to let me know. He has bee on thryoid med for a week but i seeno change in his behavior. Other that the paranoia, he shows no other signs of dementia. How do I handle this? Thanks.