What causes bipolar disorder?

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Bipolar disorder is a brain disorder that results in extreme changes of mood, energy and effects one’s ability to function. Although research has greatly increased our understanding of why someone might develop bipolar disorder, there is no simple answer as to the precise cause.

  • Scientists believe that bipolar disorder is the result of interplay between genetic and environmental factors. Current theories suggest that a person inherits a “vulnerability” to bipolar illness, meaning they are more susceptible to developing the disorder. However, this is not the only factor in determining whether a person will become ill. Environmental factors such as stressful life events also appear play a role in that they can lead to the onset of the illness or “trigger” an episode (a relapse of symptoms) in someone who already has the illness.

  • Family, twin and adoption studies show that bipolar disorder can run in families although not everyone with a family history will develop this disorder. First-degree relatives (parents, children, siblings) are more likely to have a mood disorder. For example, a person with one parent who has bipolar has a 15-30% risk for developing the disorder.


  • It is clear that even if a person has a family member with the illness, only a minority will eventually develop bipolar illness. There is another part to this equation – environmental factors. Researchers believe that in some individuals, stressful life events that can trigger the illness. Stressful events are varied and might include grief over a death in the family, trauma, loss of a job, the birth of a child or moving into a new home. Alcohol or drug abuse may also play a role

  • Researchers have also looked at what might be the activities in the brain that cause these extremes in mood and impaired ability to function.There is evidence to suggest that bipolar disorder is the result of abnormalities in the way some of the nerve cells in our brain communicateamong one another. Nerve cells communicate with each other through chemical messengers called neurotransmitters. When there are problems in the functioning of these neurotransmitters, the communicationsystem in the brain can be disrupted.


Researchers have known for decades that a link exists between neurotransmitters and mood disorders, as specific medications which alter these transmitters can also relieve mood disorders. In short, researchers are quite certain that the neurotransmitter system is at least part of the cause
of bipolar disorder, but further research is still needed to define its exact role.

So the bottom line, according to today’s thinking, is that if you have bipolar disorder, you were likely born with the possibility of developing this disorder, and for many a stressful life event and/or upbringing can trigger the onset or lead to recurring episodes.

 

 

 

 

 


Developed by the Mood Disorders Association of British Columbia. For information on support for people with mood disorders and their families please visit our website www.mdabc.net. Funding for this fact sheet was made possible by the Provincial Health Services Authority.



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