132 Bipolar and Related Disorders
toms of mania, such as rapid speech, racing thoughts, distra ctibility, and less need for
sleep. The “double counting” of symptoms toward both ADHD and bipolar disorder can
be avoided if the clinician clarifies whether the symptom(s) represents a distinct episode. 
Personality disorders. Personality disorders such as borderline personality disorder
may have substantial symptomatic overlap wi th bipolar disorders, since mood lability
and impulsivity are common in both conditions . Symptoms must represent a distinct ep-
isode, and the noticeable increase over baseline required for the diagnosis of bipolar dis-
order must be present. A diagnosis of a personality disorder should not be made during an
untreated mood episode.
Disorders with prominent irritability. In individuals with severe irritability, particularly
children and adolescents, care must be take n to apply the diagnosis of bipolar disorder
only to those who have had a clear episode of  mania or hypomania—tha t is, a distinct time
period, of the required  duration, during which the irritability was clearly different from
the individual’s baseline and was accompan ied by the onset of Criterion B symptoms.
When a child’s irritability is persistent and pa rticularly severe, the diagnosis of disruptive
mood dysregulation disorder wo uld be more appropriate. Indeed, when any child is being
assessed for mania, it is essential that th e symptoms represent a clear change from the
child’s typical behavior.
Comorbidity
Co-occurring mental disorders are common, wi th the most frequent disorders being any
anxiety disorder (e.g., pa nic attacks, social anxiety disorder [social phobia], specific pho-
bia), occurring in approximatel y three-fourths of individuals; ADHD, any disruptive, im-
pulse-control, or conduct disorder (e.g., intermittent explosive disorder, oppositional