Aetna Intelihealth
Aetna: Inteli Health: How Does Depression Develop?
This page contains short descriptions of the causes of depression. There is a link to more information for each cause.
WebMD
Web Md: Depression Guide
This site from WebMD Health provides great information on depression. Includes a section on the facts of depression, types of depression, causes, diagnosis, treatment options, care giving, and different populations information.
Aetna Intelihealth
Aetna: Inteli Health: Bipolar Disorder
Thorough overview of bipolar disorder. Includes information on symptoms, diagnosis, treatment, and much more.
The National Alliance on Mental Illness
National Alliance on Mental Illness: Depression
This site is a concise page from NAMI describing depression, its causes and symptoms, statistics, treatment, and more.