What causes bipolar disorder? Scientists aren’t actually sure, but are taking into consideration several risk factors, such as genes, brain structure, and environmental causes.
Genetic studies of twins have shown promising results with regards to bipolar disorder. According to a a study by Berit Kerner, “The heritability of bipolar disorder based on concordance rates for bipolar disorder in twin studies has been estimated to be between 60% and 80%.” However, if one identical twin develops Bipolar I, the rate of the other twin developing it is roughly 40%, compared to fraternal twins at 5%. Parents have a 10 to 15% chance to pass bipolar disorder to their children if one parent has the disorder, compared to 30 to 40% if both do. This means genetics play a crucial role in the transmission of bipolar disorder.
Recent evidence suggests that the structure of the brain may contribute to people developing bipolar disorder. MRI studies have found the over-activation of the amygdala, which processes memory, helps decision-making, and controls emotional reactions. People who are manic showed decreased activity in the interior frontal cortex, which assists problem solving, memory, language, judgment, and impulse control. Certain psychiatric medications work on neurotransmitters, suggesting that these messenger chemicals play a significant role in the function of bipolar disorder, but no one knows how exactly they’re responsible.
Stress is a significant predictor of bipolar disorder in people who are susceptible to the disease. Life events such as childbirth, trauma, job loss, or grief over a death in the family may trigger a mood episode. My mania and subsequent psychosis was set off by the birth of my first child, but my second child’s birth did not trigger anything. However, substance abuse, hormonal issues, and altered health habits can also spark the illness.
Many factors set in motion the development of bipolar disorder. With more research, scientists will discover the roots of the disease, and possibly be able to prevent it in the future.