Researchers don't know exactly what causes bipolar disorder. Most likely, there's no single factor but rather multiple factors that cause bipolar disorder to develop. Genetics do play a role and increase the likelihood that someone will develop the disorder. But you can't always determine who will get it based on genetics. For example, although the disorder does run in families, one twin may develop the disorder while the other twin never does. Statistics show that the children of bipolar patients have a higher risk than the general population of developing it. Attempts to find the specific genes that lead to the disorder have failed, but research is ongoing [source: NIMH].
Environmental factors might actually contribute to the development of the disorder in someone who is genetically predisposed. For instance, stressful periods and major life-altering events -- both good and bad -- can trigger the disorder. Other environmental factors have the potential to cause specific manic and depressive episodes in bipolar patients. These include drug and alcohol abuse, seasonal changes and even antidepressants [source: Helpguide.org].
Chemicals in the brain could also predispose people to bipolar disorder [source: CCI]. Researchers suspect that the levels of neurotransmitters dopamine, serotonin, norepinephrine, and GABA (gamma aminobutyric acid) might be involved in the disorder. Because cocaine and amphetamine, which release dopamine, can instigate mania, it is possible that high dopamine levels could lead to a manic episode [source: Davies]. This theory is supported by the evidence that manic and psychotic symptoms correlate with increased dopamine levels [source: Frank]. In addition, researchers have found low serotonin activity during manic and depressive episodes [source: Frank]. Also, hypomania often correlates with increased norepinephrine levels. Compared to healthy patients, bipolar patients have lower levels of an enzyme used in the transfer of GABA in the brain. It is thought this plays a role in causing the disorder because anticonvulsant drugs, which are effective in combating bipolar disorder, increase the levels of GABA [source: Frank].
The more scientists find out about the causes of the condition, the more progress they can make toward finding effective treatments. Luckily, many bipolar patients benefit from existing medications. Next, we'll take a look at the most common medications used to treat bipolar disorder.