Blood Tests For Antidepressants, Are They Worth It Yet?

Health Professional

Last Spring, I went to a conference in which blood tests for deciding the "right' medication for mood disorders was discussed. These tests determine how a person metabolizes a certain medication, then the doctor could decide what is best for his patient. They were specifically talking about antidepressants, but other medications are being examined even as we speak.

I have been asked a few questions about these tests and thought I would pass a little knowledge onto you. One test that I am frequently asked about is the CYP450 -- the full name being, Cytochrome P450 (abbreviated CYP, P450, or CYP450).

I am a Psychologist, not a Geneticist, but do know that the CYP450 is not a terribly new test. It has been around for many years but the idea of using it for antidepressant metabolism is a relatively new one. The problem with this particular testing is that currently it is only used for SSRI testing, and that does not include SSNRI, tricyclics, or MAO Inhibitors. Testing and interpretation are time-consuming, inconvenient, and require the patient to be free of all drugs at the time of testing.

There were no data regarding whether CYP450 testing adults entering SSRI treatment for depression led to improved outcomes; if testing results were useful in medical, personal, or public health decision making; or if there were harms associated with testing or subsequent management options. There also were several limitations to the quality of evidence, which would need to be considered when designing future studies of the utility of CYP450 genotyping or of any type of genetic testing in clinical practice (American Family Physician).

I've done a lot of reading about CYP450 regarding testing for antidepressants and found this government website that said the following:   "The Evaluation of Genomic Applications in Practice and Prevention (EGAPP) Working Group found insufficient evidence to support a recommendation for or against use of cytochrome P450 (CYP450) testing in adults beginning selective serotonin reuptake inhibitor (SSRI) treatment for non-psychotic depression. In the absence of supporting evidence, and with consideration of other issues, EGAPP discourages use of CYP450 testing for patients beginning SSRI treatment until further clinical trials are completed."   (National Guideline Clearing House).

All that being said, if you consider the cost and the time worth it, then go ahead, but sadly enough, there is no strong evidence that it will help you in the end. There will be in time and if we can be patient, then doctors and patients alike will all benefit.