Bipolar disorder has no single cause. It appears that certain people are genetically predisposed to bipolar disorder.Some brain imaging studies show physical changes in the brains of people with bipolar disorder. Other research points to neurotransmitter imbalances, abnormal thyroid function, circadian rhythm disturbances, and high levels of the stress hormone cortisol.
Here are the common causes of bipolar disorder:
Stressful life events can trigger bipolar disorder in someone with a genetic vulnerability. These events tend to involve drastic or sudden changes–either good or bad–such as getting married, going away to college, losing a loved one, getting fired, or moving.
While substance abuse doesn’t cause bipolar disorder, it can bring on an episode and worsen the course of the disease. Drugs such as cocaine, ecstasy, and amphetamines can trigger mania, while alcohol and tranquilizers can trigger depression.
Certain medications, most notably antidepressant drugs, can trigger mania. Other drugs that can cause mania include over-the-counter cold medicine, appetite suppressants, caffeine, corticosteroids, and thyroid medication.
Episodes of mania and depression often follow a seasonal pattern. Manic episodes are more common during the summer, and depressive episodes more common during the fall, winter, and spring.
Loss of sleep—even as little as skipping a few hours of rest—can trigger an episode of mania.