Antidepressant Roulette

Antidepressants, medications for depression, don't work the same for each individual. Many times, depression patients have to try several antidepressants before finding the right one.

So what's the story? Why don't antidepressants work as well as, say, antibiotics?

Lots of reasons, says experts. First, unlike antibiotics, which can be tested against specific bacteria, there's no way to test an antidepressant against individual depressions. "Every antidepressant is a different molecule," says Bradley Gaynes, M.D., associate professor of psychiatry at the University of North Carolina's School of Medicine in Chapel Hill and one of the co-investigators of STAR*D.

That means, in terms of antidepressant side effects and efficacy, they affect people differently. For instance, two people taking the same depression drug at the same dosage may wind up with different amounts in their blood because of how their bodies metabolize the antidepressant medication. Or one may get very nauseous from the drug while the other feels just fine. Studies are emerging that suggest a significant part of resistance to a particular antidepressant may be related to genetic variations in certain proteins that carry the drug to the brain.^i,ii

The other thing, notes Dr. Gaynes, is that no single antidepressant is any better than another. It all depends on the individual patient. That means that choosing an antidepressant is often like playing roulette. You pick one and just hope it works. And that, notes Jeffrey D. Dunn, Pharm.D., formulary and contract manager with SelectHealth, inc., in Salt Lake City, Utah, can lead to poor outcomes and, on the part of patients, poor adherence.

So when choosing an antidepressant, says Dr. Gaynes, you and your doctor should consider issues like cost, side effects, safety and any other medical conditions you have. For instance, if you have insomnia, your doctor may recommend an antidepressant with some sedating effects, like Remeron. Conversely, if you have no energy, the energizing effects of an SSRI like Prozac might work better. If sexual side effects are a concern, Wellbutrin might be a better option, either alone or in addition to an SSRI.

Choosing Antidepressants Based on Science

While there is currently no objective "test" to predict how people will react to a specific antidepressant, researchers are beginning to investigate certain biomarkers, such as brain wave patterns, that may provide some clues.ⁱⁱⁱ

They are also learning that certain depression symptoms may predict who will respond to certain depression medications. For instance, one study found that people with more severe depression, other mental or physical health conditions, and "atypical" depression marked by "leaden paralysis" and extreme fatigue are less likely to respond to the antidepressant Cymbalta (duloxetine).^iv They also found that women tend to respond better to Celexa (citalopram) than men.^v

Ideally, someday there will be a simple blood test that tells your doctor which antidepressant will work best for you.