Did you know that as much as some doctors and researchers like to think that medicine is a science, it is very much an art too?

You can see that no more clearly than in the decision process doctors use to prescribe a specific psychiatric medication. Ask a psychiatrist what their usual depression treatment regimen is, and they’ll usually talk to you about using one or two different antidepressants they are most familiar and comfortable with prescribing — not which medication is best for the patient.

Why is that? Wouldn’t you like to prescribe the most effective medication for a particular patient based upon their brain’s chemical structure and likely reaction to it? We sure would, but until recently, we had few ways to determine how a person might react to particular antidepressant medication.

Luckily, the days of trial and error and guesswork in this particular area of treatment may be coming to an end.

A new medical test — called a biomarker test — appears to help predict a patient’s response to a specific antidepressant. The test is non-invasive, painless and fast, taking about 15 minutes. Six electrodes (which measure brain activity) are placed around the forehead and on the earlobes (the electrodes don’t hurt — they are only measuring devices).

Here’s what the study found:

Subjects were then randomly assigned to continue with escitalopram or were given a different drug. A total of 73 patients who remained on escitalopram were tracked for 49 days to see if their results matched the prediction of the ATR biomarker. The ATR predicted both response and remission with an accuracy rate of 74 percent, much higher than any other method available.

The researchers also found that they could predict whether subjects were more likely to respond to a different antidepressant, bupropion, also known as Wellbutrin XL.

So although this test only worked on two medications — Lexapro and Wellbutrin XL — it’s a very good start in this area. And while 74 percent may not seem high, it’s much better than the current prescription strategy of trial and error, where only one-third of patients will respond to the randomly selected antidepressant medication they are prescribed (according to STAR*D, and then it’s more trial and error for those remaining two-thirds).

This test also shows the likely future of medical tests for serious mental conditions such as clinical depression. Rather than traditional blood-work laboratory tests, we’re far more likely to see these kinds of brainwave measuring devices. Such devices help collect data on how our brain is functioning and reacting, without any needles or pain. And while we’ve long been aware of their usefulness for a wide range of applications (from brain research to neurofeedback treatments), this is the first study of its kind demonstrating a simple way to discriminate between drugs and their effectiveness in our brains.

I can imagine that perhaps in a few more years, we’ll have biomarker tests for virtually all psychiatric medications, taking a large part of the guesswork out of the equation. And providing patients with better, more targeted care, more quickly.

Read the full article: Test Selects Best Depression Medication

Dr. John Grohol is the CEO and founder of Psych Central. He is an author, researcher and expert in mental health online, and has been writing about online behavior, mental health and psychology issues -- as well as the intersection of technology and human behavior -- since 1992. Dr. Grohol sits on the editorial board of the journal Cyberpsychology, Behavior and Social Networking and is a founding board member and treasurer of the Society for Participatory Medicine.

    Last reviewed: By John M. Grohol, Psy.D. on 21 Sep 2009
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