Bipolar II Disorder 137
this pattern is present, it is noted by the specifier “with rapid cycling.” By definition, psy-
chotic symptoms do not occur in hypomanic episodes, and they appear to be less frequent
in the major depressive episodes in bipolar II di sorder than in those of bipolar I disorder. 
Switching from a depressive episode to a manic or hypomanic episode (with or with-
out mixed features) may occur, both spontane ously and during treatment for depression.
About 5%–15% of individuals with bipolar II disorder will ultimately develop a manic ep-
isode, which changes the diagnosis to bipolar I disorder, regardless of  subsequent course. 
Making the diagnosis in children is often a challenge, especially in those with irritabil-
ity and hyperarousal that is nonepisodic  (i.e., lacks the well-demarcated periods of altered
mood). Nonepisodic irritability in  youth is associated with an elevated risk for anxiety dis-
orders and major depressive disorder, but not bipolar disorder, in ad ulthood. Persistently
irritable youths have lower familial rates of bipolar disorder than do  youths who have bi-
polar disorder. For a hypomanic episode to be  diagnosed, the child’s symptoms must ex-
ceed what is expected in a given environment and culture for the child’s developmental
stage. Compared with adult onset of bipolar II disorder, childhood or  adolescent onset of
the disorder may be associated with a more severe lifetime course. The 3-year incidence
rate of first-onset bipolar II disorder in adults older than 60 years is 0.34%. However, dis-
tinguishing individuals older than 60 years with bipolar II disorder by late versus early
age at onset does not appear to have any clinical utility.
Risk and Prognostic Factors