Which requires a higher dose of medicine, anxiety or depression?

A therapist writes in with the following question: 

I had a disagreement with a psychiatrist. I’d thought that in using SSRI’s to treat anxiety–social phobias, social anxiety, etc.–LOW doses are usually given. (5-10mg of Celexa/day). Treating depression usually requires HIGHER doses, (20-60mg Celexa/day).  She maintained that higher doses of SSRI’s are required to treat anxiety, higher than those used to treat depression. Can you comment?
Aaron S., MA

I’m afraid I’m going to have to disagree with both of you.  The effective dose of antidepressant to treat the patient has less to do with the disorder and more to do with the individual patient.  Some patients require larger doses to treat their disorder, some get by with less.  There is no specific trend to suggest that anxiety disorders, per se, require either higher or lower doses.  It depends on the patient’s physiology and there is no way to gauge that.  Underlying the different response patterns is a complex combination of differences in metabolic rates (some patient’s livers metabolize the medicine faster than others), gastrointestinal absorption patterns, and differences in innate neurophysiology.  Now when we treat a patient’s anxiety with antidepressants, it is not uncommon to need to be gentle at first.  Remember what you are doing when you give a patient an SSRI–you are blocking the natural recycling process and allowing a greater amount of the neurotransmitter (serotonin in this case) to be present between the nerve cells.  That can, especially at first, cause a transient increase in anxiety in some patients.  The remedy for that is to back off the dose and go more slowly.  The ultimate dose that will be effective for the anxiety, however, is very individual and is completely unpredictable.  Note also that this initial anxiety from antidepressants is not uncommon in depressed patients without anxiety.

The one exception to this rule is the treatment of OCD.  This disorder classically requires larger doses of SSRIs for longer periods of time in order to achieve clincial response.  For example, with Celexa, it would not be uncommon to use 60 mg to treat OCD (standard high dose is 40).  A more typical medicine would be Prozac, Zoloft or Paxil.  But again, you tend to need the higher dose range (even above the typical FDA max doses).  In addition, you must wait longer before considering the med trial a failure since response might not kick in for 3-4 months.

Dan Hartman, MD