-- Question: What are antidepressants (such as Prozac, Cymbalta), how do they work, and how are they used to treat anxiety disorders?
Answer: The reason that antidepressants can be used for anxiety disorders is that depression and anxiety share a common pathological mechanism. That is to say that in both of these disorders, there is not enough serotonin that exists between nerve cells in the brain. As a result, drugs such as SSRIs may serve to increase the amount of available serotonin so that impulses can travel along the nerve cells in the brain. SSRIs, such as Prozac, Paxil or Lexapro, may serve to increase the amount of available serotonin, whereas SNRIs, in addition to doing this, also increase the amount of norepinephrine in the space between two nerve cells.
Other drugs, such as benzodiazepines, act at other receptors, such as GABA receptors, which are also important in anxiety. What we do know is that these drugs work. Prior to giving people drugs, one of the main brain structures that is involved in anxiety is the amygdala. The amgydala is shown to activate too much in anxiety disorders. When we give people SSRIs, this amygdala activation is reduced, showing us that the drug actually has an affect on the brain that correlates with an improvement in symptoms.