Ramona Lamascola thought she was losing her 88-year-old mother to dementia. Instead, she was losing her to overmedication. Last fall her mother, Theresa Lamascola, of the Bronx, suffering from anxiety and confusion, was put on the antipsychotic drug Risperdal. When she had trouble walking, her daughter took her to another doctor — the younger Ms. Lamascola’s own physician — who found that she had unrecognized hypothyroidism, a disorder that can contribute to dementia. Theresa Lamascola was moved to a nursing home to get these problems under control. But things only got worse. “My mother was screaming and out of it,...