Can Your Genes Tell Your Doctor Which Depression Drug Will Work?

Slowly, but surely, the time is nearing when doctors will use information on patients’ genes to guide medical decisions, a practice sometimes called “personalized medicine.”

New research suggests that genetic analysis could help a doctor recommend the best drug to treat a patient’s depression. That would be major progress for a field of medicine that relies heavily on trial and error.

Researchers from the National Institute of Mental Health evaluated how more than 1,800 depressed people responded to the drug citalopram (Celexa). They also looked at whether people had certain gene variations (called GRIK4 and HTR2A). Those who had both of these gene variations were 23% more likely to get better with citalopram than those who had neither of them.

Both genes described in this new research affect chemical messengers in the brain. These chemicals, serotonin and glutamate, are thought to play important roles in how the brain regulates mood. So, it makes sense that these genes would interact with how a person responds to a depression drug.

Scientists don’t know everything they’d like to know about how antidepressants work and this study is a case in point. Citalopram is one of a group of drugs that have been known to affect serotonin selectively. So it was a surprise to learn that variations in a glutamate gene (GRIK4) changed a person’s response to the drug. The other gene — HTR2A — affects serotonin. This new research suggests that citalopram may work through both chemical messengers.

For people suffering with depression, this kind of research could help to shorten the time between diagnosis and effective treatment. When doctors prescribe medicine for people with a newly diagnosed depression, it may take weeks to judge whether the person is getting a good effect. If not, the doctor can adjust the dose or try a new medicine. Side effects may lead to dose changes, too. It takes time to assess the response after every adjustment. Finding the best treatment can take months. Using genetic information to speed up this process could be a very big deal.

It’s too early for your doctor to begin recommending genetic testing. Not enough research has been done yet to clarify how to use the tests. But these results (along with other similar research) point the way to a future approach to providing depression treatment.

Until that future comes, we should continue to focus on encouraging people with depression to overcome any reluctance to seek help. After all, many people with symptoms of depression do not tell their doctors about it, so their depression goes undiagnosed.

If you already receive treatment for depression and haven’t noticed a big difference yet, be patient. It can take quite a while to see improvement. Switching medicines or increasing the dose too quickly can lead to side effects. Or, you may give up too soon on a drug that would have been helpful. Also keep in mind that there’s more than one way to treat depression. Psychotherapy also helps many people.

Nearly 1 in 10 adults will suffer from some form of depression in a given year, affecting not only them, but also their friends and family. Thankfully, years of research and recent breakthroughs have made this serious illness easier to treat. With Understanding Depression, a special health report from Harvard Medical School, you can stay up-to-date on the latest information on depression symptoms and treatments to improve your life—or the life of someone close to you.

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