Depressive disorders come in different forms and with different levels of severity.  The following is a brief description of three of the most prevalent types of depression disorders.  However, within these types there are variations in the number of symptoms, their severity, and persistence.

Major depression is manifested by a combination of symptoms (see symptom list) that interfere with the ability to work, sleep, eat, and enjoy once pleasurable activities.  These disabling episodes of depression can occur once, twice, or several times in a lifetime.

A less severe type of depression, Dysthymia, involves long-term, chronic symptoms that do not disable, but keep a person from functioning at "full steam" or from feeling good.  Sometimes, people with dysthymia also experience major depressive episodes.

Another type is Bipolar Disorder, formerly called manic depressive illness.  Not as prevalent as other forms of depression, bipolar disorder may involve cycles of depression and elation or mania.  Sometimes the mood switches are dramatic and rapid, but most often they are gradual.  When in the depressed cycle, a person may have any or all of the symptoms of a depressive disorder.  When in the manic cycle, any of all symptoms listed under mania may be experienced.  Mania often affects thinking, judgment, and social behavior in ways that cause serious problems and embarrassment.  For example, unwise relationship, business or financial decisions may be made when an individual is in a manic phase.  Bipolar disorder is often a chronic recurring condition.