While medical professionals and researchers have not yet determined the exact cause of bipolar disorder, certain factors do increase a person’s chance of having the illness.

Research and studies are continually looking for more information on the causes and risk factors for this mental illness, as this understanding can help with treatment and prevention.

Risk Factors

Most medical professionals believe that genetics and heredity play a role in the development of bipolar disorder. Approximately 80 percent to 90 percent of people with the illness have a family member who also suffers from the condition.

Children with one parent who has the illness have a 15 percent to 30 percent chance of developing it, while children with two parents who have the condition have a 50 percent to 75 percent chance of developing it.

If one sibling has bipolar disorder, other siblings have a 15 percent to 25 percent chance of developing the illness.

Twin studies have been done to determine whether or not the condition’s causes are entirely genetic, and it has been determined that they are not. Many people with a family history of the illness will never develop it. Also, people without a family history can develop the illness.

It has been observed that most cases of bipolar disorder occur in teenagers or young adults, although children and older adults can develop the illness as well. The illness affects all races equally, and men and women are equally likely to develop it.

Other illnesses may also put people at risk for developing the condition.

Possible Causes

There are many possible causes of bipolar disorder, including:

  • Abnormal Size of Brain Areas: Bipolar disorder patients often have certain parts of the brain that are shaped differently than an average brain. However, it is not known if these irregularities are the cause of the condition or if they are simply symptoms of the illness.
  • Imbalance in Brain Chemicals: Many people with this illness have imbalances of certain chemicals (neurotransmitters) in the brain. This makes it difficult for brain cells to function normally or properly.
  • Imbalance in Hormone Levels: A number of bipolar disorder sufferers have hormone levels that differ from those of people without the condition.


Certain environmental factors, such as drug abuse and stressful or traumatic life events, are thought to contribute to the development of bipolar disorder. However, not all people who use drugs or undergo stressful events develop the condition. Therefore, these factors are often called triggers.

Certain things are thought to trigger the illness in people who are already predisposed to it. These include:

  • antidepressants
  • change in hormonal levels
  • chronic illness
  • death of a family member or close friend
  • hypothyroidism
  • lack of sleep
  • stress.


Many illnesses can have symptoms similar to those of bipolar disorder, so it’s important to see a medical professional for an accurate diagnosis.

Certain medications and illnesses may present similar symptoms, so it is necessary to rule out these possible causes before attributing symptoms to bipolar disorder.



Bipolar.com (2007). Causes and Risk Factors. Retrieved July 18, 2007, from the Bipolar.com Web site: http://www.bipolar.com/what_is_bipolar/


Bipolardepressioninfo.com (2007). Patient Guides. Retrieved July 18, 2007, from the Bipolardepressioninfo.com Web site: http://www.bipolardepressioninfo.com/ms/guides/

Mayo Clinic (2007). Bipolar Disorder. Retrieved July 18, 2007, from the Mayo Clinic Web site: http://www.mayoclinic.com/health/bipolar-disorder/DS00356/DSECTION=3.

Zyprexa (2007). Causes of Bipolar Disorder. Retrieved July 18, 2007, from the Zyprexa Web site: http://www.zyprexa.com/bipolar/understanding/

 Posted on : June 13, 2014