After earning a degree in biology and German from Rice University in 1995, Dr. Johnston completed medical school at the National University of Ireland at Cork in 2003. Dr. Johnston completed his residency in Internal Medicine at The University of Texas Medical School at Houston in 2006 and a fellowship in Rheumatology at the University of Washington in Seattle in 2008. Dr. Johnston is a fellow of the American College of Rheumatology and a member of the American College of Physicians, Osteoarthritis Research Society International, Texas Medical Association and the Harris County Medical Society. When he's not caring for patients, Dr. Johnston frequently participates in half marathons.