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Finding an antidepressant that works isn't easy or fast for most people—and some 40 percent of the most troubled patients never do.
Why does it take so long? Your doctor may be working from a short list of drugs covered by your insurance, and not start with her first choice for you. To give a drug a fair shake, you should wait about two months for a response. Along the way, your doctor may decide to up the dose, adding more time, before switching drugs. Often psychiatrists try people on drug combinations. Shaky hands, headache, nausea, weight gain, and erectile dysfunction are all possible side-effects. But sometimes those effects fade, and your doctor might encourage you to stick it out.
Put it all together and too many people go from one drug to the next for months or even years. That journey, complete with side-effects and the cost of the drugs, is a depressing one in itself.
Many people give up. Some get partial relief.
For readers who favor other ways of dealing with depression, let me say that taking a medication doesn't stop anyone from seeing a therapist or getting more exercise or sleep or quitting sugar or leaving a bad job or marriage. The trouble is that very depressed people need a boost to make changes. They may need a boost to do much at all.
The sooner they feel even a little bit better, the sooner they can examine root causes and decide what to do next. .
Gene tests offer help that you'll get to the right drug faster—which means fewer people will drop out of the process or settle for a clouded existence.
Some warnings: The research behind these tests is young and the tests are unregulated; they do not require approval from the Food and Drug Administration. However, the key science comes from well-regarded sources, the Mayo Clinic and Cincinnati Children's Hospital.
John Logan Black, MD, a psychiatrist at Mayo Clinic in Rochester, Minn., recommends that people in the following groups consider a gene test:
People who are severely depressed or suicidal—they need the right drug fast.
People who have a personal or family history of significant side effects from medication of any kind.
People who have tried and so far failed to find an effective antidepressant without bothersome side-effects.
Very young or very old people who can’t handle side effects or communicate well about symptoms are also candidates.
Genetic testing can help doctors decide if you are most likely to respond to antidepressants that work mainly on serotonin, the SSRIs, such as Paxil, Celexa, and Lexapro, or to the drugs that also work on other neurotransmitters, which include Effexor and Cymbalta. A test can also help doctors pick within the serotonin group and help target dosages.
Nearly all medications for depression are metabolized by two enzymes in your liver: CYP2D6 and CYP2C19. Your genes are the most important factor that determines how much of these enzymes you produce: too much makes you process the medication quickly, too little can lead to a build-up that causes side effects. As many as 45 to 55 percent of all people in the United States may be low on one of the enzymes, which is why side effects are so common.
Your response to drugs that work on serotonin is affected by the chemical 5HTT or the pathways CYP1A2 or NAT2. About 40 percent of Americans carry gene variations that may make them less likely to respond to SSRIs.
Local and regional laboratories may not do these tests, but can send your blood or cheek swab sample to a lab specializing in pharmacogenetics, the technical term for gene testing that predicts a person’s response to a drug. Assurex Health, Genelex, Geonomind, and Mayo Clinic produce reports that will interpret the results and give your doctor recommendations for antidepressants and dosages.
Assurex Health, which uses technology patented by Mayo Clinic and Cincinnati Children’s Hospital, offers a test called GeneSight, which has won Medicare approval to treat depression after extensive vetting, and a contract with the U.S. Department of Veterans Affairs to help psychiatrists treating post-traumatic stress disorder. Patients who get this test are more likely to stick with their medication than those who don’t, early research shows.
Your own insurer may not cover the cost, but you can ask your doctor to write a letter or file an appeal of a decision to deny coverage. Several testing companies offer financial assistance to some patients.
A version of this story appears on Your Care Everywhere.
