At the age of 44, my great-grandmother Carmela became convinced that people were out to get her. She refused to let anyone visit her house in Modesto, California, where she lived with her husband, two children, and sister-in-law. She insisted that all the windows and curtains be closed. She had hallucinations and manic episodes. Sometimes she would rush out of the house into the street for no reason, and her children would have to chase her and bring her back home.