Depressive Disorders - Causes

The causes of depressive disorders are not well understood. Most experts believe that an imbalance of neurotransmitters is a major factor. Neurotransmitters are chemicals in the brain. They are responsible for carrying messages from one part of the brain to another. The presence of too many or too few neurotransmitters can cause the brain to perform abnormally.

Environmental factors are also thought to be involved in depressive disorders. It is believed that children who are abused or neglected may later develop a depressive disorder.

Heredity also seems to play a role in depressive disorders. People whose families have a history of major depression are up to three times more likely to have the disorder themselves. Many scientists now think that genetic and environmental factors work together to cause depressive disorder. Heredity may predispose (make a person more likely to have) a person toward depressive disorder. But the condition develops only if the environment in which he or she grows up allows the condition to appear.