pressive symptoms and the medical condition.
Substance/medication-induced bipolar and related disorder and substance/medica-
tion-induced depressive disorder. Substance/medication-induced bipolar and related
disorder and substance/medica tion-induced depressive diso rder are distinguished from
cyclothymic disorder by the judgment that  a substance/medication (especially stimu-
lants) is etiologically related to  the mood disturbance. The fr equent mood swings in these
disorders that are suggestive of cyclothymic disorder usually resolv e following cessation
of substance/medication use.
Bipolar I disorder, with rapid cycling, an d bipolar II disorder, with rapid cycling.
Both disorders may resemble cyclothymic disorder by virtue of the frequent marked shifts
in mood. By definition, in cyclothymic disord er the criteria for a major depressive, manic,
or hypomanic episode has never been met, wh ereas the bipolar I di sorder and bipolar II
disorder specifier “with rapid cycling” requ ires that full mood ep isodes be present. 
Borderline person ality disorder. Borderline personality diso rder is associated with
marked shifts in mood that may suggest cyclothymic disorder. If the criteria are met for
both disorders, both borderline personality disorder and cyclothymic disorder may be di-
agnosed.
Comorbidity
Substance-related disorders and sleep disorder s (i.e., difficulties in initiating and main-
taining sleep) may be present in individuals with cyclothy mic disorder. Most children
with cyclothymic disorder treated in outpati ent psychiatric settings have comorbid mental
conditions; they are more likely than other pediatric patients with  mental disorders to
have comorbid attention-defi cit/hyperactivity disorder.