He received his doctoral degree at the Minnesota School of Professional Psychology (currently Argosy University), in Egan, Minnesota. After completing his fellowship in Pediatric Psychology at St. Jude Children's Research Hospital in Memphis, Tennessee, he continued on as their pain psychologist. He went on to pursue further pain management and palliative care opportunities at the University of Colorado/Children's Hospital of Denver and Loyola University Medical Center/Ronald McDonald Children's Hospital in Maywood, Illinois. Dr. Popenhagen joined Phoenix Children's Hospital in early 2013, and is serving as the Program Director of the Complex Chronic Pain Program.