Genes

• Studies reveal that bipolar disorders may be inherited. Some families have a higher incidence of bipolar disorders. Some researchers are looking for a bipolar gene.
  
  

Stress

• Many environmental situations may cause manic or depressive symptoms. Good or bad events, such as marriage, a job loss, a financial windfall or a divorce, can cause the disorder.
  
  

Biochemical Changes

• Biochemicals in the brain are called neurotransmitters. These chemicals affect a person's emotions and behavior. When the levels of the brain chemicals change, this can cause bipolar symptoms.
  
  

Hormonal Imbalances

• The body has many hormones that regulate its various processes. When there is too much or too little of a hormone, mood changes can happen.
  
  

Changes in the Brain

• Brain scans have shown that people with bipolar disorders have physical changes in their brains. At this point, researches don't know how to explain the correlation between the mood disorder and brain changes.