Major Depressive Disorder (MDD): Also known as Clinical Depression or Unipolar Depression. The most common form of depression. It can be just a single episode, but some people may experience it periodically throughout their lives.
Postpartum Depression: A type of depression usually brought on by the hormonal shifts women experience the months or year following childbirth.
Seasonal Affective Disorder (SAD): Depression caused by a change in the circadian rhythm of the body, usually bringing on depression during a specific season of the year.
Situational Depression: While the symptoms are much like Major Depressive Disorder, this is depression brought on by a specific event, such as the death of a loved one or a life-threatening event.
Persistent Depression: Also known as dysthymia or chronic depression, this is depression that lasts for two years or more.
Manic Depression/Bipolar Disorder: Characterized by periods of mania alternating with periods of intense depression.