The causes of bipolar disorder have not yet been precisely determined; however, genetics seem to play a large role. 80-90% of people diagnosed with bipolar disorder have a family history of either bipolar or major depression. However, this does NOT necessarily mean that someone with such a family history will inherit the genetic predisposition of the disease, or if they do, that it will eventually develop into symptoms.

• See an overview of the heritability and genetics of bipolar disorder - including a chart with estimated risks for various relatives of someone with bipolar

Like other complex disorders such as schizophrenia or cancer, researchers are coming to believe that bipolar disorder is caused by an interplay between certain inherited genes (which have yet to be conclusively identified) and certain environmental factor that may act on these genes to produce the biological events of bipolar disorder within the brain. Because bipolar disorder probably has many contributing factors, and because there is a large spectrum of severity within the diagnostic category of bipolar disorder, there is likely an individual combination of causes for each case. For example, one individual may have many relatives with psychiatric disorders in their family, and therefore inherit many of the genes that make them susceptible to developing a psychiatric disorder themselves. Another individual may not have as many of the identified genetic markers, but may experience lots of highly traumatic environmental events that cause certain biological reactions in their brains to produce the mood swings of bipolar disorder.

Nothing that research has identified at this point can determine exactly who will or will not develop bipolar disorder, or any other brain disease. Even some individuals who have a long history of bipolar disorder in their family do not develop bipolar disorder themselves.

The Environmental Contribution to Bipolar Disorder:

What environmental factors may contribute to bipolar disorder are still being determined; however, researchers have preliminarily identified certain events or environments that are more highly correlated with individuals who go on to develop bipolar disorder. It is important to be aware that these factors are still correlational - it is not known at this point whether they tend to occur more within bipolar populations because they contribute to the onset of the disease, or because they are a result of the disease itself. However, even as scientists continue to investigate the causes of bipolar disorder, it may be prudent for people who know they are at higher genetic risk (due to affective disorders in their family) to take some precautions where possible.

Below are some of the possible contributors to bipolar disorder, as well as preventatitve actions that you can take to hopefully reduce your own risk, and that of your family members.

• A family history of psychiatric disease, esp. affective disorders, schizophrenia, ADHD, or VCFS increases the risk of bipolar disorder
• Obstetric complications during delivery may increase the risk of bipolar disorder for the offspring
• Low birth weight may increase risk of bipolar disorder for offspring
• High Essential Fatty Acid and Anti-oxidant Intake During Pregnancy and During Development May Help Prevent Bipolar Disorder, and/or Reduce Symptom Severity
• Substance abuse (esp alcoholism) may increase the risk of bipolar disorder
• Children born in the winter/early spring have a slightly increased incidence of bipolar disorder
• Urban birth or residence may increase the risk of bipolar disorder
• Significant or chronic childhood stress/trauma (esp. losing a parent) may increase the risk for bipolar disorder
• Head injury may increase the risk of bipolar disorder

A Preventative Approach to Bipolar Disorder:

Although there is no way we know of to definitively preven or cure bipolar disorder, the best preventative measure right now is being informed and aware. If you have a family history of mood disorders, knowing the signs and symptoms to watch for will increase your likelihood of recieving an early diagnosis and treatment, which makes the disease much more manageable in the long run. Knowing what factors tend to put someone at risk (see above), and knowing what your genetic risk might be, will help you to take some logical precautions that may help reduce your risk or lessen the severity of a future episode.

Further reading on the causes of bipolar disorder:

• Details on the Causes of Bipolar Disorder - From The US Surgeon General's Report (2002)
• The Genetics of Bipolar Disorder
• The Bipolar Disorder Gene Hunt
• Let's Talk Facts About Bipolar (American Psychiatric Association fact sheet)
• What Causes Bipolar Disorder? (National Electronic Library for Health - Mental Health)

Recent News Updates on Research into the Causal factors in Bipolar Disorder:

• Families With Severe Form Of Bipolar Disorder Help Scientists Narrow The Search For Disease Genes (April 2003)
• Discovery That Common Mood Disorders Are Inherited Together May Reveal Genetic Underpinnings (Jan 2002)
• Gene Variation Raises Risk Of Bipolar Disorder And Schizophrenia (April 2003)
• UCSD Researchers Identify Gene Involved In Bipolar Disorder (June 2003)
• UCSD Biologists Discover That Nerve Activity, Not Just Genetics Controls Kinds Of Neurotransmitters Produced (June 2004)
  
• Genes Play A Bigger Role In Women's Depression Than In Men's, Twin Study Finds (July 1999)