Major depression affects nearly 15 million people in the United States each year, according to the National Institute of Mental Health. It is the leading cause of disability for people ages 15 to 44. Depression responds well to treatment, ideally with both psychotherapy and medication. Many drugs treat depression, and careful consideration and consultation with a psychiatrist are necessary to choose the right medication for anyone's particular case. Understanding the classes of antidepressant drugs can help patients to be better informed about the options.
Selective Serotonin Reuptake Inhibitors
Selective serotonin reuptake inhibitors, or SSRIs, are the most common drug treatment for depression. According to MayoClinic.com, precisely how SSRIs improve depression is not known. However, research indicates that increasing particular neurotransmitters in the brain, such as serotonin, affects mood and may alleviate depression. While imbalances in at least three neurotransmitters in the brain are linked to depression and anxiety, SSRIs work only on serotonin levels. SSRIs impede the reabsorption of serotonin by certain nerve cells, thus making more serotonin available. A wide range of side effects can occur in patients taking SSRIs, and there are serious risks as well. SSRIs include Paxil, Prozac, Lexapro, Celexa, Zoloft and Luvox.
Serotonin and Norepinephrine Reuptake Inhibitors
Only three U.S. Food and Drug Administration approved SNRIs were on the market as of July 2010: Cymbalta, Pristiq and Effexor. Serotonin and norepinephrine reuptake inhibitors function similarly to SSRIs. However, they increase levels of both norepinephrine and serotonin in the brain. Like serotonin, norepinephrine is a neurotransmitter in the brain associated with mood and behavior. In addition to treating depression, SNRIs are approved to treat certain anxiety disorders. Like SSRIs, they can cause a wide range of side effects, some of them serious.
Older Antidepressants
Psychiatrists rarely prescribe tricyclic antidepressants or MAOI inhibitors anymore, now that many newer antidepressants have come onto the market that cause less severe and less frequent side effects. Tricyclic antidepressants inhibit the reabsorption of serotonin, norepinephrine and dopamine. However, according to mayoclinic.com, tricyclics also block other nerve cell receptors, which causes their many side effects. Monoamine oxidase inhibitors, or MAO inhibitors, were developed in the 1950s and have been in use since. Like tricyclic antidepressants, they affect levels of all three of the neurotransmitters most associated with mood, though they work in a different manner to do so.
Atypical Antidepressants
The final group of antidepressants is atypical antidepressants, so called because they do not fit into the other categories and neither do they form a coherent class of drugs of their own. According to mayoclinic.com, these drugs typically cause fewer sexual side effects. The most common of these antidepressants is Wellbutrin, which affects levels of norepinephrine and dopamine. It poses the lowest risk of sexual side effects of all the antidepressants. Trazodone, Mirtazapine and Nefazodone are the other atypical antidepressants. Trazodone and Mirtazapine have the potential to be quite sedating. Nefazodone poses particular health risks.
Non-Antidepressant Drugs
Certain other drugs have been shown to improve especially treatment-resistant depression, or to help with more complex depression such as in bipolar disorder. They are almost always prescribed in conjunction with another antidepressant to augment treatment. Abilify is one such drug. Developed as an antipsychotic drug, it is prescribed to treat bipolar disorder as well, and as an adjunctive therapy for treatment-resistant major depression.
