As you might now, there are currently 3 widely accepted forms of bipolar
disorder, that is,
bipolar type I,
bipolar type II, and cyclothymia. However, a spectrum view of
bipolar disorder is becoming popular. For example, you can picture a line with unipolar depression (major depression only) at point A, and with full blown bipolar type I at the end of the line, point B. If a person has major depression only, then they will fall close to point A on the line.