Hassan joined Kaiser Permanente in 2001 and has held many positions with the Southern California Permanente Medical Group, including assistant chief of the Department of Internal Medicine; assistant physician-in-chief of the Division of Nephrology; medical director of the Hemodialysis Unit; physician-in-charge of the Alton-Sand Canyon Medical Offices; and interim chief of the Department of Neurology.
Hassan was educated at the University of California, Irvine, where he earned a bachelor's degree in biological sciences, a doctoral degree in pharmacology, and a medical degree. He completed a fellowship in nephrology and hypertension at Harbor-University of California at Los Angeles Medical Center. He has also traveled widely and speaks Persian, German, English, and Spanish.