Genetic, chemical, hormonal, psychological, social and developmental factors may also play a role. Close relatives of individuals who have bipolar disorder are definitely at risk so heredity plays a role. Stress may trigger an episode but is not usually accepted as a cause of the illness. Another theory is that bipolar disorder stems from a defect in the brains internal clock, which controls daily and seasonal rhythms. Another is that an episode of depression, hypo mania or mania may alter brain chemistry in ways that create a predisposition to future episodes.
Research continues seeking a definitive cause.
Until the cause is found there will be no cure. Cycles Changes in mood, thinking, behavior and physical condition for a distinct period of time, either to depression or mania, characterize bipolar disorder. These changes occur in cycles. An episode of mania may be followed closely by an episode of depression or vice versa. Each individual is different but to experience 4 or more major episodes in a ten year span is not unusual.