The cause is unknown. Risk factors include a family history of bipolar disorder. First-degree relatives of people with<unk>  have major depressive disorder, bipolar I disorder, and bipolar II disorder more often than the general population. Substance-related disorders also may be at a higher risk within the family. First-degree relatives of a bipolar I individuals may have a higher risk of<unk>  disorder than the general population.
Cyclothymia
Substance use disorder
Dysthymia
Borderline personality disorder
Euthymia 
Bipolar disorder
Congenital athymia
Myokymia