McHugh was born in Lawrence, Massachusetts, the son of a Lowell High School teacher and a homemaker. He graduated from Harvard College in 1952 and from Harvard Medical School in 1956. In 1979, in his capacity as chair of the Department of Psychiatry, McHugh ended gender assignment surgery at Johns Hopkins Hospital. Former psychiatrist-in-chief for Johns Hopkins Hospital and now its current Distinguished Service Professor of Psychiatry at the Johns Hopkins University School of Medicine, Dr. McHugh is the author, co-author, or editor of seven books within his field. His expertise includes: Adult Psychiatry, Neuropsychiatry. Research interests include: Behavioral Research; Psychiatric Education.