Dr. Johnson received his MD from University of Colorado Health Sciences University and his Ph.D. in pharmacology from Oregon Health & Science University (OHSU). Dr. Johnson completed his neurology residency at OHSU in 1989.

Dr. Johnson joined the OHSU Movement Disorder faculty in 1990 and is now a Professor of Neurology. He maintains an active basic science program that investigates changes in brain neurochemistry that occur in animal models of Parkinson's disease. He is widely known nationally and internationally for his work that has characterized neuropharmacological actions of dopamine in the brain.

Dr. Johnson is also an expert clinician and has expertise in the clinical diagnosis and treatment of Parkinson's disease and other movement disorders.