According to a January 2010 report by the Centers for Disease Control and Prevention, approximately 21 percent of Americans will have a mood disorder in their lifetime. The mood disorders include the depressive disorders, which can be controlled or treated. There are several different types of antidepressant medications that are used as part of therapy.
Defining Mood Disorders
People are experiencing a mood disorder if they have long periods of extreme sadness, long periods of extreme joy or go through long periods of both sadness and joy, according to the Merck Manuals Online Medical Library. The extreme sadness is also referred to as depression, while the periods of extreme joy are called mania. Cyclothymic, bipolar and depressive are different types of mood disorders. Antidepressant medications are used to treat depressive disorders.
MAOIs
The term, MAOI stands for monoamine oxidase inhibitor. Monoamine oxidase is a protein that helps break down the monoamine chemicals that the nerves use to send signals. These chemicals include norepinephrine, serotonin and dopamine. One of the theories on depression suggests that it occurs because people do not have enough norepinephrine, serotonin or dopamine, explains Charles DeBattista, M.D., Professor of Psychiatry and Behavioral Sciences at Stanford University School of Medicine in "Basic & Clinical Pharmacology." MAOIs stop the breakdown of these chemicals and are used to treat depression when other antidepressants do not work.
SSRIs
Selective serotonin reuptake inhibitors, or SSRIs, are another class of antidepressants. Normally after serotonin is released by a nerve cell, it crosses a small gap to reach the next nerve cell. The signal is then passed on to the following nerve cells in the same way. SSRIs interfere with a nerve cell taking serotonin after it crosses the gap. In other words, they interfere with the reuptake of serotonin. Thus, serotonin stays in the gap longer than normal and repeatedly stimulates the next nerve cell. Dr. DeBattista writes in "Basic & Clinical Pharmacology," that SSRIs are the most common antidepressant medication used to treat depression.
Heterocyclic Antidepressants
The heterocyclic antidepressant medications were once the main treatment for depression, but are hardly used anymore because of their side effects, according to 2009 information from the Merck Manuals Online Medical Library. These medications primarily work by increasing the amount of norepinephrine in the gap between the nerve cells. They do this by interfering with the reuptake of norepinephrine. To a smaller extent, they also interfere with the reuptake of serotonin. When heterocyclic antidepressants are taken for some time, these medications affect certain proteins on the membrane of nerve cells.
Serotonin Antagonists
These antidepressant medications antagonize, or block, the serotonin receptor on the nerve cell. Receptors are proteins on a cell membrane or within a cell that act once they have been given instructions on what to do. After these medications are broken down, they block the serotonin receptor, according to "Basic & Clinical Pharmacology." In this way, the serotonin molecule cannot attach to the receptor, which means these medications increase the amount of serotonin in the gap between nerve cells.
References
- "Basic & Clinical Pharmacology"; Bertram Katzung, M.D., Ph.D., Susan Masters, Ph.D., Anthony Trevor, Ph.D.; 2009
- Centers for Disease Control and Prevention: Public Health Surveillance for Mental Health
- Merck Manuals Online Medical Library: Mood Disorders
