Richard G. Petty, MD

Genetic Testing in the Treatment of Depression

By a remarkable “coincidence,” less than a week after the appearance of two items (1. 2.) questioning the value of using genetic testing to help predict response to treatment in people suffering from depression, an important report has been released today.

The report is supported by a collaboration of the Agency for Healthcare Research and Quality and the Centers for Disease Control (CDC) and Prevention’s National Office of Public Health Genomics, and it was the CDC that funded it.

It is gratifying to see that the findings of the report are identical to those published in the two articles last week. The main conclusion of the report is that there is insufficient evidence to determine if current gene-based tests intended to personalize the dose of medications in a class of drugs called selective serotonin reuptake inhibitors (SSRIs) improve patient outcomes or aid in treatment decisions in the clinical setting.

The investigators reviewed 1,200 abstracts that led to the final inclusion of 37 articles. As we learned last week, the evidence indicates the existence of tests with high sensitivity and specificity for detecting only a few of the more common known polymorphisms of the cytochromes 2D6, 2C19, 2C8, 2C9, and 1A1.

They found mixed evidence regarding the association between CYP450 genotypes and SSRI metabolism, efficacy, and tolerability in the treatment of depression, mainly from a series of heterogeneous studies in small samples.
There were no data regarding:

  1. If testing for CYP450 polymorphisms in adults starting SSRI treatment for non-psychotic depression leads to improvement in outcomes versus not testing, or if testing results are useful in medical, personal, or public health decision making.
  2. If CYP450 testing influences depression management decisions by patients and providers in ways that could improve or worsen outcomes.
  3. If there are direct or indirect harms associated with testing for CYP450 polymorphisms or with subsequent management options.

This report confirms that there is little point in doing these genetic tests.

It also raises another point. It is now some years since some of these tests became available commercially. If they were really of value then we have to ask why there hasn’t been an avalanche of research on the topic – especially by the people marketing the tests – and why none of major psychopharmacology groups in the United States, Europe, Japan or Australia picked up on the tests. I probably know most of the people in these hospitals, universities and research centers and none has been much interested in this work.

So when someone suggests that you undergo some new test or investigation, remember to use your common sense. If there is only one person doing it – whether it’s a genetic test, a brain scan, some non-standard type of thyroid or adrenal test, or a Vega test – ask why nobody else is using it and why nobody has published any decent research on the method.

When it comes to your health use your common sense, your intuition and impartial information to be your guide and your support.

About Richard G. Petty, MD
Dr. Richard G. Petty, MD is a world-renowned authority on the brain, and his revolutionary work on human energy systems has been acclaimed around the globe. He is also an accredited specialist in internal and metabolic medicine, endocrinology, psychiatry, acupuncture and homeopathy. He has been an innovator and leader of the human potential movement for over thirty years and is also an active researcher, teacher, writer, professional speaker and broadcaster. He is the author of five books, including the groundbreaking and best selling CD series Healing, Meaning and Purpose. He has taught in over 45 countries and 48 states in the last ten years, but spends as much time as possible on his horse farm in Georgia.

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