Cyclothymic Disorder 139
symptoms of ADHD, such as rapid speech, racing thoughts, distractibility, and less need
for sleep, overlap with the symp toms of hypomania. The double  counting of symptoms to-
ward both ADHD and bipolar II disorder can be avoided if the clinician clarifies whether
the symptoms represent a distin ct episode and if the noticeab le increase over baseline re-
quired for the diagnosis of bipo lar II disorder is present. 
Personality disorders. The same convention as applies for ADHD also applies when
evaluating an individual for a personality disorder such as borderline personality disor-
der, since mood lability and impulsivity are common in both personality disorders and bi-
polar II disorder. Symptoms must represent a di stinct episode, and the noticeable increase
over baseline required for the diagnosis of bipo lar II disorder must be present. A diagnosis
of a personality disorder should not be made during an untreated mood episode unless
the lifetime history supports the pr esence of a personality disorder.
Other bipolar disorders. Diagnosis of bipolar II disorder should be differentiated from
bipolar I disorder by carefully considering whether there have been any past episodes of
mania and from other specified and unspecifie d bipolar and related disorders by confirm-
ing the presence of fully synd romal hypomania and depression.
Comorbidity
Bipolar II disorder is more often than not associated with one or more co-occurring mental
disorders, with anxiety disorders being the most common. Approximately 60% of individ-
uals with bipolar II disorder  have three or more co-occurr ing mental disorders; 75% have
an anxiety disorder; and 37% have a substa nce use disorder. Children and adolescents
with bipolar II disorder have a higher rate  of co-occurring anxiety disorders compared