Bipolar Disorder Causes

The exact cause of bipolar disorder has not been discovered, but many experts believe that multiple factors are involved which act together to cause the disease. Bipolar disorder may result from a chemical imbalance within the brain. The brain's functions are controlled by chemicals called neurotransmitters. An imbalance in the levels of one of these neurotransmitters, such as norepinephrine, may cause bipolar disorder. When levels of this chemical are too high, mania occurs. When levels of norepinephrine drop below normal levels, a person may experience depression. Levels of other neurotransmitters, such as serotonin and dopamine, are also believed to play a role.

There is a significant genetic component to bipolar disorder. If a family member has bipolar disorder, other family members may be at risk. The identical twin of a person with bipolar disorder is at the highest risk for developing the condition. However, stress of some kind often is needed to trigger the onset of the disease. The disease does not occur just because of one gene, and the cause of the disease is likely a combination of multiple genetic and environmental factors.

Sometimes a period of emotional stress, drug use, an illness, or another event seems to trigger the onset of the disease. Stresses can also trigger a manic or depressive episode in people who are known to have the condition.

Not everyone with severe mood swings or a change in personality has bipolar disorder. Mood swings can be caused by other medical conditions that need to be diagnosed and treated properly. Medical diseases and medications that may have symptoms similar to bipolar disorder include the following:

• Head trauma (blood clot or bleeding in the brain)
  
  
• Thyroid problem (both underactive and overactive)
  
  
• Systemic lupus erythematosus (a condition that may affect various body organs, including the brain)
  
  
• Brain tumor
  
  
• Epilepsy (seizures)
  
  
• Neurosyphilis (a form of the sexually transmitted disease, syphilis, that has gone to the brain because it went untreated too long)
  
  
• AIDS (acquired immunodeficiency syndrome, the ultimate result of infection with the human immunodeficiency virus or HIV)
  
  
• Sodium imbalance (sodium, one of several elements found in body cells that is necessary for their proper function)
  
  
• Diabetes mellitus (a disorder of, among other things, sugar processing in the body)
  
  
• Certain medications that decrease the amount of serotonin or norepinephrine, such as some antihypertensive drugs and some preparations of steroids and birth control pills