Causes of bipolar disorder

Because bipolar disorder tends to run in families, researchers have been searching for specific genes, passed down through generations that may increase a person's chance of developing the illness. Evidence has also indicated that social stresses and life events can act to trigger Bipolar Disorder.

Genetic causes

The evidence that heredity plays a role in the development of some forms of mental illness has been discovered by studying identical twins who were raised separately, and comparing them to non-identical twins raised separately and the general public.

Twin studies
For example, if an identical twin has manic depression, the other twin will also develop it 40-80% of the time. With non-identical twins, when one twin is affected the chance of the other twin developing the condition is 15-20%. Close relatives such as parents, children and siblings (first-degree relatives) have a 5-10% chance.

The neurotransmitter system
The chemical messenger system of the body - has received a great deal of attention as a possible cause of bipolar disorder. Researchers have known for decades that there is a link between neurotransmitters and mood disorders, because drugs which alter these transmitters also relieve mood disorders. Some studies hypothesize that a low or high level of a specific neurotransmitter such as serotonin, norepinephrine or dopamine is the cause, or that they are imbalanced. Other studies have found that a change in sensitivity in nerve cells that receive the chemical messages is at least part of the cause of bipolar disorder.

Psychological causes

The main psychological cause that can lead to the onset of symptoms of bipolar disorder is stressful life events. These can range from a death in the family to the loss of a job, from the birth of a child to a move. Stresses and strains may be different from one person to another.