This document discusses symptoms, causes, and treatments for depression. It lists common symptoms like difficulty concentrating, fatigue, guilt, and changes in appetite or sleep. It describes warning signs of suicide for those with depression, such as talking about death, losing interests, and putting affairs in order. The brain regions affected by depression are also outlined. Depression can affect people of any age but is more common in teenagers and adults around age 40. Heredity and gender also influence depression risk, with women being more than twice as likely to experience depression as men. Common antidepressant medications work by increasing serotonin levels in the brain.