Both genetic elements and environmental factors can create vulnerability to the disorder, so the causes vary from person to person.
While the disorder can run in families, no one has definitively identified specific genes that create risk for developing the condition. There is some evidence that advanced paternal age at conception can increase the possibility of new genetic mutations that underlie vulnerability.
Imaging studies have suggested there may be differences in the structure and function of certain brain areas, but no differences have been consistently found.
Life events including various types of childhood trauma are thought to play a role. Scientists do know that once bipolar disorder occurs, life events can precipitate recurrences. Incidents of interpersonal difficulty and abuse are most commonly associated with development of the disorder.