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Causes of Bipolar Disorder

What Causes Bipolar Disorder?

Bipolar disorder is a complex illness. No single factor seems to be responsible for its development. However, researchers continue to try and pin down the cause so that the illness can be treated more effectively.


According to the American Academy of Child and Adolescent Psychiatry, anyone who has a parent or sibling with bipolar disorder has a four to six times higher risk of developing the mental illness when compared with a person whose family tree does not include relatives with bipolar disease. Identical twins have a 40 to 70 percent chance of bipolar disorder if one twin is diagnosed. These findings suggest a genetic component to the disorder. Researchers are trying to find the specific gene changes responsible for these increased inheritable risks for the development of bipolar disorder.

Age and Gender

People between the ages of 15 and 25 have an increased risk of bipolar disorder. At least half of all cases are diagnosed before the age of 25. However, bipolar disorder has been diagnosed in children as young as six. Some do not develop symptoms until they are in their 30s or 40s.

Bipolar 2 disorder is more common in women than in men. However, bipolar 1 disorder is equally prevalent in both sexes.

Biological Abnormalities

Scientists are working to discover differences in the brains of people with bipolar disorder. Some notable discoveries have already been made. For instance, in bipolar patients:

  • Research has suggested that the loss or damage of brain cells in the hippocampus can contribute to mood disorders. This is the part of the brain associated with memory. It also indirectly affects mood and impulses.
  • Research suggests that mitochondrial problems may play a role in a number of psychiatric diseases, including bipolar disorder. Mitochondria are the energy centers found in almost every human cell. Some believe that brain metabolism becomes abnormal in particular regions of the brain when the mitochondria in those regions don’t work properly. This abnormality may contribute to abnormal patterns of energy production and utilization by the affected cells. This may potentially explain some of the behaviors we see in patients with psychiatric disorders.
  • Neurotransmitters are chemicals that help brain cells communicate. Imbalances in the neurotransmitters, which play an important role in mood regulation, are linked to bipolar disorder.

Environmental and Lifestyle Factors 

Some scientists believe that environmental and lifestyle factors play a role in bipolar disorder. Extreme stress, physical or sexual abuse, or other traumatic events may play a role in the development of the disorder. 

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