Factors that contribute to bipolar disorder are: 1. Genetic predisposition: Biology Certain people seem to have a genetic predisposition. However, not everyone with a genetic predisposition develops the disorder. This suggests that genes are not the only cause. Some brain imaging studies have shown that people with bipolar disorder have changes in brain structure. Other studies have found patients with neurotransmitter imbalances, abnormal thyroid function, circadian rhythm disturbances, and high cortisol levels. 2.External environment and psychological factors: External factors are called triggering factors. Triggering factors can lead to manic or depressive episodes or worsening of existing symptoms. Many patients with bipolar disorder do not have obvious triggering factors. (1) Stress: Stressful life events can lead to bipolar episodes in people with a genetic predisposition. Life events are often usually major events such as marriage, college, loss of a loved one, career, and relocation, with no good or bad outcomes. (2) Substance abuse: Substance abuse does not cause bipolar disorder; it can cause episodes or exacerbate the condition. Drugs such as ecstasy and amphetamines can induce mania, while alcohol and tranquilizers can trigger depression. (3) Medications: Antidepressants can trigger mania. Cold medicine, appetite suppressants, caffeine, glucocorticoids, and thyroid medications can cause mania. (4) Seasonal changes: Manic and depressive episodes tend to have seasonality. Manic episodes often occur in the summer, and depressive episodes often occur in the fall, winter and spring. (5) Sleep deprivation: Sleep deprivation can trigger mania.