In the US, we use the Diagnostic Statistical Manual (DSM) to help guide the diagnostic process. Throughout the years, this manual has undergone several updates, helping to align the guidelines with current research findings. Your job is to research Depressive and Bipolar Disorders and see how the diagnostic criteria have changed throughout the DSM editions. Try to get a complete picture, if possible, but make sure to use at least one other edition beyond the DSM-5. If the disorder did not exist before a certain edition, and you want to include it, you can write about why the disorder was finally added. Write a brief synopsis of your findings, making sure to properly cite your sources in APA format. This does NOT mean copy/paste the DSM. Write about how the diagnostic criteria have changed, why they were changed, and your opinion on what the impact of those changes were (i.e., how did treatment change, how did stigma change, etc.).
