Bipolar personality disorder

Bipolar personality disorder was a medical condition characterized by extremes of emotion.

Following Lon Suder's murder of Frank Darwin in 2372, Kes found no tendency towards bipolar disorder in Suder's neurogenetic markers. 

In 1996, The Doctor told Henry Starling that his belief that the USS Voyager crew was attempting to steal "his" timeship, because they thought he'd be an easy target, was a paranoid response indicative of bipolar personality disorder.