There are two main types of mood disorders that cause Depression: Unipolar Depression (or “regular” or “plain” Depression) and Bipolar Depression. There are other conditions that are also associated with depression such as Adjustment Disorder, PTSD, ADD, etc… but I will be limiting the discussion here to Unipolar vs. Bipolar Depression because this is often a source of misunderstanding. Because in both cases the patient is seeking treatment for Depression, and the features of the Depressed episode can be exactly the same, the only true distinguishing feature between Unipolar and Bipolar Depression is that with Bipolar Depression there are times the person feels the opposite of depressed, with a distinctly elevated or expansive mood, energy and activity level.
This is where the term “Bi-polar” comes from, as a person varies between 2 poles or opposite ends of the mood spectrum. This is in contrast to Unipolar Depression, which is sometimes referred to as plain or regular depression, where alterations in mood vary only in the down or depressed direction. When not depressed, people with Unipolar Depression return to a level mood, but never an expansive or ecstatic one. There are two main types of Bipolar Disorder: Type 1, where the “up” phases are extreme and problematic, and Type 2, where the “up” phases themselves are not a problem, are usually experienced by the person as their best and most productive self, and simply serve as a marker to identify the type of mood disorder. Although the highs in Type I can be obvious, Type II can be particularly overlooked because the patient never seeks care when they are in the “up” phase (you never hear, “Doctor, this is the best I’ve ever felt, please do something about it!”) — they understandably come for treatment when they are depressed, just like patients with Unipolar Depression.
As above, because the Depressed episode itself can look exactly the same, when a patient is seeking evaluation and treatment for Depression, it is important to determine the pattern of mood variation over time to distinguish between a Bipolar and Unipolar Depression. It is not that one type of Depression is better or worse than the other, it is just that an accurate diagnosis determines proper treatment. Certain types of Counseling and Medication work best for one but not the other.
Regards, Dr. Ranen (Baltimore/Owings Mills Psychiatrist). (Also see the Depression and Bipolar Support Alliance website http://www.dbsalliance.org)