Bipolar disorder

Note on usage: "Manic-depression" was the original term used for the disorder. While it is still commonly used to refer to bipolar disorder, the term manic depression is also now used (by a relatively small number of mental health professionals) to refer to the entire clinical spectrum of mood disorders that includes both bipolar disorder and unipolar depression. Others are trying to phase out the term entirely.

Research findings

Heritability

Bipolar disorder appears to run in families. The rate of suicide is higher in people who have bipolar disorder than in the general population. In fact, people with bipolar disorder are about twice as likely to commit suicide as those suffering from major depression (12% to 6%).

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The rate of prevalence of bipolar disorder is roughly equal in men and women. Lifetime risk of bipolar I disorder is often quoted as around 1%, but when bipolar II is included the true rate may be around 4%.{{ref|kess_prev}}

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More than two-thirds of people with bipolar disorder have at least one close relative with the disorder or with unipolar major depression, indicating that the disease has a heritable component. Studies seeking to identify the genetic basis of bipolar disorder indicate that susceptibility stems from multiple genes. Scientists are continuing their search for these genes using advanced genetic analytic methods and large samples of families affected by the illness. The researchers are hopeful that identification of susceptibility genes for bipolar disorder, and the brain proteins they code for, will make it possible to develop better treatments and preventive interventions targeted at the underlying illness process.

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Recent genetic research

Bipolar disorder is considered to be a result of complex interactions between genes and environment. The monozygotic concordance rate for the disorder is 70%. This means that if a person has the disorder, an identical twin has a 70% likelihood of having the disorder as well. Therefore, the genetic component makes up about 70% of the risk for the disorder. Relatives of persons with bipolar disorder also have an increased incidence of having unipolar depression.

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In 2003, a group of American and Canadian researchers published a paper that used gene linkage techniques to identify a mutation in the GRK3 gene as a possible cause of up to 10% of cases of bipolar disorder. This gene is associated with a kinase enzyme called G protein receptor kinase 3, which appears to be involved in dopamine metabolism, and may provide a possible target for new drugs for bipolar disorder.{{ref|Barr_2003}}

Related Topics:
Gene linkage - GRK3 - G protein receptor kinase 3 - Dopamine

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Medical imaging

Researchers are using advanced brain imaging techniques to examine brain function and structure in people with bipolar disorder, particularly using the functional MRI. An important area of imaging research focuses on identifying and characterizing networks of interconnected nerve cells in the brain, interactions among which form the basis for normal and abnormal behaviors. Researchers hypothesize that abnormalities in the structure and/or function of certain brain circuits could underlie bipolar and other mood disorders. Better understanding of the neural circuits involved in regulating mood states may influence the development of new and better treatments, and may ultimately aid in diagnosis.

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Personality types

An evolving literature exists concerning the nature of personality and temperament in Bipolar Disorder patients, compared to Major Depressive Disorder (unipolar) patients and non-sufferers. Such differences may be diagnostically relevant. Using MBTI continuum scores, bipolar patients were significantly more extroverted, intuitive and perceiving, and less introverted, sensing, and judging than were unipolar patients. This suggests that there might be a correlation between the Jungian extraverted intuiting process and bipolar disorder.

Related Topics:
MBTI - Jungian

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