Bipolar II
disorder (BP-II; pronounced
"type two bipolar disorder") is a bipolar spectrum disorder (see also Bipolar
disorder) characterized by at least one episode of hypomania and at least one episode of major
depression. Diagnosis
for bipolar II disorder requires that the individual must never have
experienced a full manic episode (unless it was caused by an
antidepressant medication; otherwise one manic episode meets the criteria for bipolar I disorder). Symptoms of mania and
hypomania are similar, though mania is more severe and may precipitate psychosis.
The hypomanic episodes associated with bipolar II disorder must last for at
least four days. Commonly, depressive episodes are more frequent and more
intense than hypomanic episodes. Additionally,
when compared to bipolar I disorder, type II presents more frequent depressive
episodes and shorter intervals of well-being. The course of bipolar II disorder
is more chronic and consists of more frequent cycling than the course of
bipolar I disorder. Finally,
bipolar II is associated with a greater risk of suicidal thoughts and behaviors
than bipolar I or unipolar depression. Although bipolar II is commonly
perceived to be a milder form of Type I, this is not the case. Types I and II
present equally severe burdens.
Bipolar
II is difficult to diagnose. Patients usually seek help when they are in a
depressed state. Because the symptoms of hypomania are often mistaken for high
functioning behavior or simply attributed to personality, patients are
typically not aware of their hypomanic symptoms. As a result, they are unable
to provide their doctor with all the information needed for an accurate
assessment; these individuals are often misdiagnosed with unipolar depression. Of
all individuals initially diagnosed with major depressive disorder, between 40% and
50% will later be diagnosed with either BP-I or BP-II. Substance abuse disorders (which have
high comorbidity with BP-II) and periods of mixed depression may also make it
more difficult to accurately identify BP-II. Despite the difficulties, it is
important that BP-II individuals are correctly assessed so that they can
receive the proper treatment. Antidepressant
use, in the absence of mood stabilizers, is correlated with worsening BP-II
symptoms.