Daniel X Freedman (1921–1993) was a psychiatrist and educator, pioneer in biological psychiatry.
Born in Lafayette, Indiana, he performed pioneering studies in the relationship between drugs and behavior. Researching brain mechanism in allergy, he discovered the link of hallucinogens to brain transmitters. He also found biological effects of environmental stress on the brain, and identified hyperserotonemia in autism.
After attending Harvard College, Dr. Freedman enlisted in the army. He later attended Yale Medical School and ultimately became Professor of Psychiatry at Yale until 1966 when he left Yale to become Chairman of the Psychiatry department at the University of Chicago where he continued his psychopharmaceutical research, primarily concerned with 5-hydroxytryptamine (serotonin). The final phase of his career was spent at UCLA as professor of Psychiatry. His wife, Mary Freedman was a very talented artist who created all her own Christmas cards.