Simplified and updated from the previous edition, this chart provides an easy-to-understand visual and textual overview of the most important aspects of depression. It defines depression and three main types of this serious medical condition: major depression, dysthymic disorder/dysthymia, and bipolar disorder. The areas of the brain affected by depression are defined and illustrated. Structures of the limbic system are also shown, as any disturbance to this system can affect mood and behavior. The role of transmitters is described; illustrations show normal and abnormal levels of these important chemical messengers, which can help explain how imbalances in these chemicals can lead to depression. Signs and symptoms of major depression are prominently featured towards the top of the chart. Suicide warning signs are also detailed. Risk factors and treatment options for depression are also discussed.