One of the most common modern emotional complaints, depression is sometimes referred to as "the common cold of psychiatric illness." In its everyday usage, the word "depression" describes a feeling of sadness and hopelessness, a down-in-the-dumps mood that may or may not be directly attributed to an external cause and usually lasts for weeks or months. Sometimes it is used casually ("That was a depressing movie") and sometimes it is far more serious ("I was depressed for six months after I got fired"). Though depression has been recognized as an ailment for hundreds of years, the numbers of people experiencing symptoms of depression has been steadily on the rise since the beginning of the twentieth century.

The cause of depression is a controversial topic. Current psychiatric thinking treats depression as an organic disease caused by chemical imbalance in the brain, while many social analysts argue that the roots...