A mood disorder is a disease, like diabetes or arthritis. Just as diabetes and arthritis have to do with the body's failure to regulate the blood sugar and immune system, respectively, the mood disorders result from the brain's failure to regulate the chemicals that control mood. These same chemical imbalances can go on to affect other bodily functions, such as the regulation of sleep, appetite, sexual desire or concentration. Nerve cells in the brain communicate with each other by releasing chemicals called neurotransmitters. Norepinephrine and serotonin are two neurotransmitters involved in depression.
Antidepressant medicines work by increasing the amount of norepinephrine or serotonin.
Depression is also known to result from long periods of stress. They also can become suicidal and need hospitalization. At any one time, over 17 million Americans are depressed. Forty percent of people who have depression also have an anxiety disorder, experiencing anxiety so severe that it interferes with their lives. While some people get better on their own, most will need treatment to make a full recovery.