Dr. Johnston attended Franklin and Marshall College before going on to medical school at the University of Pittsburgh, from which he graduated cum laude in 1971. His post-doctoral training at the Johns Hopkins Hospital included work in pediatrics, neurology, pharmacology and pediatric neurology. After teaching positions and research work at the University of Michigan Medical School and University of Michigan Hospitals, Dr. Johnston returned to Baltimore in 1988. Today he is the senior vice president and chief medical officer at Kennedy Krieger Institute, as well as director of both Kennedy Krieger Institute's Division of Neurology and Developmental Medicine and the institute's neuroscience laboratory. Dr. Johnston is an attending physician at both Johns Hopkins Hospital and Kennedy Krieger Children's Hospital.