Genetic Test for Suicidal Ideation?

Actually, the full headline is: href="http://www.huliq.com/36055/genetic-test-for-suicidal-ideation-in-patients-using-antidepressant-drugs%20">Genetic
test for suicidal ideation in patients using antidepressant drugs.



A company called Neuromark has made available a genetic test that it
claims can identify persons who would have an increased risk for
suicide after starting an antidepressant medication.  They call
the test Mark-C™.  It is based upon the finding that
persons with certain genetic markers seem to be at increased risk for
having thoughts of suicide after they start taking an antidepressant.



The research that underlies this claim has not been published yet.
 ScienCentral has href="http://www.sciencentral.com/articles/view.php3?type=article&article_id=218393002">a
story about it, in which they say that the research will be
published today.  The study was done by href="http://intramural.nimh.nih.gov/mood/investigators/laje.htm">Gonzalo
Laje, M.D., at the NIMH.  Raw data came fro the href="http://www.nimh.nih.gov/health/trials/practical/stard/index.shtml">Star*D
study.



According to the ScienCentral article, the NIMH has two patents on the
use of the genetic markers, and they already have been licensed to
Neuromark.  



Maybe something useful will come of it, but it seems to me that
Neuromark is overly ambitious about this...

Some detail is in the ScienCental article:

None of the 4000-plus patients in the
trial actually committed suicide. Of the 950 patients who contributed
DNA samples, fifty percent reported suicidal thoughts before treatment,
while six percent reported such thoughts only after starting the drug.
The gene markers were much more common in this group, and having more
than one of them greatly increased the risk. But that group was small--
just one percent of 950 people.

Neuromark is planning more research to validate the study.
 Clearly there is a lot of work to be done in this area.
 



The whole issue of the relationship between antidepressants and suicide
risk has been vexing to study, with href="http://scienceblogs.com/grrlscientist/2007/09/black_box_warnings_on_antidepr.php">seemingly
href="http://scienceblogs.com/corpuscallosum/2007/08/antidepressantsuicide_risk_upd.php">contradictory
href="http://scienceblogs.com/corpuscallosum/2007/07/more_on_antidepressantsuicide.php">results
coming out on a regular basis.  



As a clinician, whenever a new test comes out, the first question I
have is this: under what circumstances would the result of the test
change what I do in the clinic?  At this point, I do not see
how the proposed test would change anything.  



Depression does increase the risk of thinking about suicide, and it
increases the risk of suicide.  The risk  is highest
around the time that the patient comes in for treatment:

href="http://scienceblogs.com/corpuscallosum/2007/07/more_on_antidepressantsuicide.php">

What this means, is that all depressed patients should be
assessed and monitored carefully during this critical time.
 Would anyone seriously consider not
assessing and monitoring carefully, based on the result of the test?
 Of course not.  So if the test comes back positive,
what does it tell you?  The only thing it tells you, is that
you should do exactly what you already
were planning to do anyway.  



I am not claiming that the test is meaningless.  It may very
well turn out to be useful in helping us figure out the basic
pathophysiology underlying suicidality, and perhaps give us some clues
about the pathophysiology of depression itself.  That would be
good.  It might help us learn more about the apparent
antidepressant-suicide link, or about the mechanism of action of
antidepressants.  That would be good too.  But until
someone can show that the test can be used to make better decisions in
the clinic, it will be a research-only tool.