Dr. Nora Volkow is the director of the National Institute on Drug Abuse at the National Institutes of Health. She studies how drugs affect the human brain. A leading research psychiatrist and scientist, Volkow sees addiction as a disease, not a moral failing. Her research has also led her to discover parallels between substance abuse and obesity. For example, a person who overeats often experiences similar changes in brain activity and behavior as that of an addict. Volkow’s family history is as intriguing as her work: She is the great-granddaughter of Russian revolutionary Leon Trotsky and grew up in the house where he was assassinated. Dr. Volkow talks about addiction and her efforts to cure it.