Hyeran Kim, MD, and colleagues report that news in The Journal of the American Medical Association.
Antidepressants are often effective. But 30% to 40% of patients don't respond to the first antidepressant they try, note Kim and colleagues.
There is no test to predict which antidepressant may work best for any given patient. But genetics may provide clues about antidepressant response, the new study shows.
Kim works in the psychiatry department of Sungkyunkwan University School of Medicine in Seoul, South Korea. Kim's team studied 241 Korean adults (average age: 54-57) with major depression.
The researchers split the patients into two groups, giving each group a different type of antidepressant.
Patients in one group took either the antidepressant drug fluoxetine (brand names: Prozac, Sarafem) or sertraline (Zoloft), for six weeks.
Patients in the other group took another drug -- nortriptyline (Aventyl, Pamelor) -- for six weeks.
The study doesn't specify whether the patients used brand-name or generic versions of those drugs.
Every two weeks, the patients were seen by a psychiatrist and completed a survey of their depression symptoms.
The researchers also screened the patients' genes -- specifically, the monoamine transporter genes.
Those genes govern the transport of three brain chemicals: serotonin, norepinephrine, and dopamine.
Certain variations of those genes were associated with a good response to fluoxetine and sertraline, which target serotonin. Other variations showed a good response to nortriptyline, which primarily targets norepinephrine, the study shows.
However, the researchers haven't totally figured out the genetics of antidepressant response.
For instance, they note that other studies have linked different gene variations to antidepressant response in whites.
Genetics is complex, and more work lies ahead, including studies of younger patients, the researchers note.
They add that if their findings are confirmed, it could help refine the antidepressant selection process.
SOURCES: Kim, H. The Journal of the American Medical Association, Oct. 4, 2006; vol 296: pp 1609-1618. News release, JAMA/Archives. WebMD Medical Reference from "Making the Antidepressant Decision": "Monoamine Oxidase Inhibitors (MAOIs)."
By Miranda Hitti
Reviewed by Louise Chang