Bipolar disorder:Etiology


 * Bipolar disorder: known evidence of causes
 * Bipolar disorder: theories of possible causes

There are many theories regarding the development of bipolar disorder. Multiple factors may be involved, such as stressful events or major life transitions, conditions in the womb, past or present drug use (which may complicate diagnoses if present and may lead to misdiagnoses), sleep deprivation, or a family history of bipolar disorder, clinical depression, or schizophrenia. This type of family history creates a genetic vulnerability which can significantly increase the likelihood of developing the disorder.

The "kindling" theory asserts that people who are genetically predisposed toward bipolar disorder experience a series of stressful events, each of which lowers the threshold at which mood changes occur. Eventually, the mood episode itself is sufficient to trigger recurring difficulties.

As with nearly all psychiatric or psychological phenomena, the etiology of bipolar disorder is thought to include a complex interplay between environmental stimuli (stressful life events, drug use, etc.) and genetic vulnerability. While bipolar disorder has a strong genetic component, the concordance rate between MZ (identical) twins, who share 100% of their DNA, is not 100%. Therefore, environmental and genetic factors must be at play.

Many drugs, legal and illegal, may initiate a manic episode. The mania induced by such drugs, including antidepressant medications and stimulants (e.g. Adderall or methamphetamines), may or may not resolve when the medication is discontinued. When a patient with a history of manic episodes requires an antidepressant because of a serious depression, a doctor typically will tread carefully, prescribing a low dose and, ideally, closely monitoring the patient for any signs of an excessive mood shift toward the manic side of the spectrum.