Reviewed by Neha Pathak on December 19, 2017
World Health Organization: "Depression."; Mayo Clinic: "Depression."; American Psychiatric Association: "What Is Depression?"; Anxiety and Depression Association of America: "Understand the Facts: Depression."; Getty; Comstock Images;i Stock/Getty Images Plus; Thinkstock; AudioJungle; Rike; Vanessa Clara Ann Vokey; Somos/Veer; KatarzynaBialasiewicz; funduck
© 2016 WebMD, LLC. All rights reserved.