Dr. Roger McIntyre, Professor of Psychiatry and Pharmacology at the University of Toronto and Head of the Mood Disorders Psychopharmacology Unit at the University Health Network in Toronto, Canada, returns to introduce depressive disorders.

We differentiate normal "low mood" from conditions that warrant a psychiatric diagnosis. We discuss historical subtypes of depression and the current DSM specifiers for major depressive disorder. We review epidemiology, discuss the neurophysiology of depressive disorders, and then dive into treatment options.