Experts don’t know what causes brief psychotic disorder. There may be a genetic link; the condition is more common in people who have a family history of psychotic or mood disorders, such as depression or bipolar disorder. Another theory suggests that poor coping skills could trigger the disorder as a defense against or escape from a very frightening or stressful situation. In most cases, the disorder is triggered by a major stress or traumatic event. For some women, childbirth can be a trigger.