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Blood Test to Assess Effectiveness of Antidepressant Medications

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Depression is a very difficult disorder to treat. Even though many drugs are available, most only work for a few years and then stop working. Consumers often go through a process of trial and error to determine which drug will work. In a desperate attempt to find such a drug, most depressed patients spend many thousands of dollars on antidepressants that never work.

So far there is no way of telling who will respond to the antidepressants and for how long they will work. Close to 60 percent of depressed patients never respond fully to the first prescribed antidepressant medication.

Now there is research which indicates that perhaps researchers can tell if an antidepressant is likely to work in a depressed patient.

With this method, a protein called vascular endothelial growth factor (VEGF) is measured in the blood. The researchers at Loyola University observed that that among depressed patients who had higher than normal blood levels of VEGF, more than 8 percent experienced partial or complete relief from depression after taking escitalopram (Lexapro®). By comparison, fewer than 10 percent of depressed patients who had low levels of VEGF responded to the drug. (1)

Dr. Angelos Halaris, MD, author of the study said that this is the first time that a test has been available to predict response to an antidepressant. If the study is validated in more patients, then it would greatly benefit patients. Doctors would be able to predict ahead of time if a given antidepressant is going to be effective.

In this small study 35 patients took escitalopram for depression. Escitalopram is classified as a selective serotonin reuptake inhibitor (SSRI). Other common SSRIs include Zoloft, Prozac and Paxil.

So far no one is sure why SSRIs work in some people and not in others. It is believed that there is a chemical imbalance in the brain that may not be responsive to the antidepressant.

In this study, researchers believe that the drug escitalopram most likely helps jump start the inactive brain. The regenerative capacity of the brain is boosted by VGEF. It is well known that VEGF can stimulate growth of blood vessels and maintains normal activity of nerves and muscles.

In depressed patients with high levels of VEGF, there may be enhanced regeneration, which then reverses depression. Conversely in people with low VEGF, there may be minimal regeneration and a lesser relief from depression.

The researchers claim that this study may help select the best treatment for the depressed patient. If the patient has low VEGF he/she may be less likely to respond to the SSRIs and may respond to other antidepressants or alternative therapies like psychotherapy or ECT.

For the consumer there are a few things of note. This is only a preliminary study and there is no direct correlation between levels of VEGF and depression. Levels of VEGF are often altered in many medical disorders including mental disorders. (2) Secondly, measurement of VEGF is also prohibitively expensive, something which is not so desirable with the current health care crises and lack of medical insurance.

Finally in my opinion, this is a very small study and a much larger study is needed before one can recommend VEGF as a measure of response to antidepressants. It is not even known whether the same response is seen with the other SSRIs and how long this association lasts.

Dr. Halaris presented the results of this during the 2011 annual meeting of the Society of Biological Psychiatry and the 4th Annual Illinois Brain, Behavior and Immunity Meeting.


1. ScienceDaily. Blood Test Might Predict How Well a Depressed Patient Responds to Antidepressants. Web, 19 Dec. 2011.
Abstract: http://www.sciencedaily.com/releases/2011/12/111215135853.htm

2. Lee BH et al. Increased plasma VEGF levels in major depressive or manic episodes in patients with mood disorders.
Abstract: http://www.ncbi.nlm.nih.gov/pubmed/21862441

Reviewed December 19, 2011
by Michele Blacksberg RN
Edited by Jody Smith

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We value and respect our HERWriters' experiences, but everyone is different. Many of our writers are speaking from personal experience, and what's worked for them may not work for you. Their articles are not a substitute for medical advice, although we hope you can gain knowledge from their insight.