Bipolar disorder, also known also as manic depression, affects nearly 5.7 million people over the age of 18 each year, according to the Depression and Bipolar Support Alliance. It is a mental illness that causes extreme shifts in moods---one day a person may be in a state of euphoria, and a few days later find themselves suffering from severe depression. Although the exact cause of this disorder is not known, several risk factors have been identified.
Genetics
The Mayo Clinic states that bipolar disorder appears to be more common in those with a blood relative (such as a parent or sibling) who is diagnosed with the disorder. Research is still being conducted to find if there are genetic cues to bipolar disorder. Steve Bressert, Ph.D., of PsychCentral states that half of those diagnosed with bipolar disorder have a family member diagnosed with a mood disorder, such as depression, and that a person with one parent diagnosed with bipolar disorder has a 15 to 25 percent chance of developing the disorder as well.
Biological Factors
Both Bressert and the Mayo Clinic concur that biological factors play a role in determining one's chances of developing bipolar.
The brain is composed of multiple neurotransmitters that are responsible for how a person thinks, acts and feels. Those with bipolar disorder appear to have a different physical composition in their brain than those who do not. Those differences typically include the chemicals norepinephrine and serotonin, among others.
It is not entirely clear how bipolar disorder develops in the brain; however, Bressert states that the disorder may lie dormant, activating on its own due to an imbalance of those chemicals, or may be triggered in response to psychological stress or environmental factors.
Environmental Factors
Environmental factors can include stress from traumatic experiences such as physical or sexual abuse or the loss of a loved one. Bressert explains that stressful life events may trigger bipolar mood episodes in people with other risk factors. Hormonal problems may also spark an episode, especially if the person suffers from imbalanced hormones.
Bressert states that substance abuse, whether it be in the form of alcohol or drugs, is not a cause, but such environmental factors can interfere with treatment by worsening the symptoms. Alcohol and many drugs are depressants and can increase the severity of a depressive episode.
Gender
The Depression and Bipolar Support Alliance (DBSA) states that although bipolar disorder is just as common in men as it is in women, women are three times as likely to experience rapid cycling, a condition in which a manic episode is followed immediately by a depressive episode.
In addition, the DBSA explains that women may be more prone to depressive and mixed episodes than men. That can be due to hormonal imbalances during menstruation, during and after pregnancy, and before and during menopause.
