The causes of bipolar disorder, also referred to as manic depressive disorder, can be difficult to pinpoint. This is because the origins of mental health issues are sometimes harder to evaluate than those that are physical in nature. Scientists believe there are several things that may cause bipolar disorder, contribute to its development, or help to trigger its episodes. They include hormonal imbalances, natural chemicals in the brain, and genetics. Scientists also believe that physical changes in a person’s brain may be at fault, and environmental factors may have a role to play in its development as well.
Hormones and hormonal imbalances are commonly considered possible causes of bipolar disorder and may cause or trigger episodes of bipolar symptoms; such imbalances, for example, commonly are associated with triggering the depression that marks the depressive phase of bipolar disorder. Hormone changes may also trigger the highs of emotion and energy that mark the manic stage.
Brain factors also are among the causes of bipolar disorder. Scientists have discovered that people who have bipolar disorder typically have physical changes within their brains. For example, those with bipolar disorder may have smaller cerebellums. Scientists are still studying how and why physical brain changes may cause or contribute to bipolar disorder.
Natural brain chemicals called neurotransmitters may also contribute to the development of bipolar disorder. These chemicals help control the normal functioning of the brain. When these chemicals are out of balance, symptoms of bipolar disorder may occur. For example, a neurotransmitter called norepinephrine may influence the emotional highs and lows typical of this condition. When norepinephrine levels are higher than normal, a person may experience mania; low levels may trigger the depressive stage.
Genetics may also be a factor in the development of bipolar disorder. When a person has a relative who has bipolar disorder, he may be more likely to develop it. Part of bipolar research involves trying to determine which genes may play a role in its development. Closer genetic relationships may translate into more likelihood that a person will inherit the genetic traits that cause or contribute to the development of bipolar disorder.
Many scientists also believe that environmental factors are among the causes of bipolar disorder. For example, a traumatic event may trigger its onset in some people. Others may develop the condition after drug use as well. Even severe emotional stress, in the presence of other factors that seem to influence bipolar disorder, may contribute to its development.