Nora D. Volkow

Nora Volkow, director of the National Institute on Drug Abuse, ranks as one of the U.S.'s leading addiction researchers. She's helped demonstrate that addiction is in fact a disease — a disease of the brain — and that all addictions, whether it's to drugs, alcohol, tobacco, sex, gambling or even food, are more alike than was previously thought.

Volkow, who's the great-granddaughter of Russian revolutionary Leon Trotsky, grew up in Mexico City — in the house where her famous ancestor was assassinated.