August 01, 2019

Can genetic testing to determine the best anti-depressant work for me?

Q: I've heard that genetic testing can help determine which antidepressant would be best for me. How does this work?

A: Genetic testing is available to help narrow down your antidepressant options, ideally reducing the need for a sometimes prolonged trial-and-error period while settling on an antidepressant regimen. Although these tests can't tell you specifically which antidepressant would work best, they offer clues about how your body may respond.

This testing — known as pharmacogenomics — looks for changes or variations in genes that determine how quickly a drug is processed (metabolized) in your body or whether you might have side effects from a certain drug.

Pharmacogenomic tests check your DNA — obtained by a blood draw or a swab for saliva — for genes that encode certain enzymes, and the results can be classified according to how fast your body metabolizes and gets rid of certain medications, such as particular antidepressants. For example, if testing indicates that your body metabolizes a drug too slowly, the drug might build up in your body and increase the likelihood of side effects. While the drug may still be useful for you, lower doses may be appropriate. On the other hand, if testing suggests that the drug would leave your body quickly, it may not have a chance to work properly or would require a larger than normal dose.

However, genetic testing has limits. Most of these tests focus on how your body metabolizes a drug rather than on how the drug influences the cause of disease — although some tests address that issue as well. Cost is also an issue, as not all insurance companies...