DEPRESSION Depression is a mood disorder that causes persistent feelings of sadness, hopelessness, loss of interest, and decreased energy. A diagnosis of major depression means symptoms have been consistent nearly every day for at least two weeks. However, depression is more than just unhappiness. It can be severe enough to interfere with relationships, work, school, and other daily activities. Doctors also refer to this condition as major depressive disorder or clinical depression. An estimated 1 in 6 people, or nearly 17 percent of Americans, will experience depression at some point in their lifetime, according to the American Psychiatric Association. About 7 percent of Americans have at least one major depressive episode per year. Although the symptoms can start at any age, depression is most likely to begin during a person's teens or 20s. Types of depression Along with major depression, there are several other types of depression, which are characterized by thei...