Temporal psychosis is a medical condition characterized by sensory aphasia, and erratic and irrational behavior. Use of a temporal transporter more than three times radically increased an individual's risk factor for developing this condition.
Captain Braxton, a 29th century Starfleet officer, succumbed to temporal psychosis as a result of his repeated interactions with the crew of the USS Voyager. This eventually led to Braxton being sent into rehabilitation and forced to retire. Holding the Voyager crew and Captain Kathryn Janeway, in particular, responsible for his circumstances, he attempted to destroy Voyager in 2375 by using a temporal disruptor, although his plan was foiled by Janeway and Seven of Nine. (VOY: "Relativity")