Bipolar disorder - Causes 

Causes of bipolar disorder 

The exact cause of bipolar disorder is unknown. However, experts believe there are a number of factors that work together and make a person more likely to develop the condition. These are thought to be a complex mix of physical, environmental and social factors.

Chemical imbalance in the brain

Bipolar disorder is widely believed to be the result of chemical imbalances in the brain. The chemicals responsible for controlling the brain's functions are called neurotransmitters and include noradrenaline, serotonin and dopamine.

If there is an imbalance in the levels of one or more neurotransmitters, a person may develop some symptoms of bipolar disorder. For example, there is evidence that episodes of mania may occur when levels of noradrenaline are too high, and episodes of depression may be the result of noradrenaline levels becoming too low.


It is also thought that bipolar disorder is linked to genetics, as the condition seems to run in families. Therefore, the family members of a person with the condition have an increased risk of developing it themselves.

However, no single gene is responsible for bipolar disorder. Instead, a number of genetic and environmental factors are thought to act as triggers.


A stressful circumstance or situation often triggers the symptoms of bipolar disorder. Examples of stressful triggers include:

These types of life-altering events can cause episodes of depression at any time in a person’s life.

Bipolar disorder may also be triggered by physical illness, sleep disturbances and overwhelming problems in everyday life, such as problems with money, work or relationships.

Page last reviewed: 08/04/2014

Next review due: 08/04/2016


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The 1 comments posted are personal views. Any information they give has not been checked and may not be accurate.

bermudj said on 19 January 2012

I have Bipolar-I. What triggers it is either medication which has such side effects, or worry. In your article you mention that the trigger could be problems in everyday life. That to me is looking at it from the outside. From the inside is worry. Now we may worry about different issues, money, family, and so on. I only have had two episodes. One came from medication for a hiatus hernia. The other was worry that I would not be able to find work. This came about from being a very shy man that always did quite bad at job interviews. The interesting aspect about this incident was that at the time I had £140.000, nevertheless the worry was so great that it triggered the illness. So to me it is the worry of how to handle the future. So it could be that one has no money and one worries how to handle the future without money and then it triggers the illness.

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