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Genetic Tests Unlikely to Improve Antidepressant Treatment

Finding contradicts claims from commercial companies (Oct. 18)

Genetic markers cannot predict which patients with major depression will respond to antidepressant drugs, according to a study led by researchers at King’s College London’s Institute of Psychiatry. Published in PLoS Medicine, the study looked at the link between genetic markers and antidepressant response.

“We found that no single genetic variant, or combination of genetic variants, could predict response to antidepressant treatment,” said senior author Dr. Rudolph Uher. “This study stands out against the background of numerous claims from commercial companies that genetic tests could help doctors decide which antidepressant to choose based on the results.”

Major depressive disorder, also known as clinical depression, is one of the top-ranking diseases in terms of lost productivity, absence from work, and healthcare costs worldwide. The prescription of antidepressants is the most common treatment, but after being given their first antidepressant, less than 50% of patients see improvement in their symptoms. This has led experts to investigate whether genetic information could be used to personalize treatment.

In the new report, the researchers drew on information from 1,790 individuals with major depression who had been given two types of common antidepressant drugs — serotonin-reuptake inhibitors (SRIs) and noradrenaline-reuptake inhibitors (NRIs). The researchers knew which patients had responded well to the drugs and had information on the genetic make-up of each patient, as each had been tested for more than 500,000 genetic variants.

The researchers conducted four genome-wide analyses. The first analysis searched for genetic markers to predict the response to both types of antidepressants in the entire sample of 1,790 individuals. The second and third analyses searched for predictors of response to SRIs (1,222 individuals) and NRIs (568 individuals). A fourth analysis searched for genetic variants that could predict a different response to these drugs.

In each case, the researchers found that no single genetic variant, or combination of genetic variants, could significantly predict the response to treatment, which was measured as a difference of at least three points in the reduction of depression symptom severity on the Hamilton Rating Scale for Depression (HRSD-17).

Finally, the researchers compared the results with data from another large-scale study, in which all participants with major depression were treated with an SRI. The combined data from 2,897 individuals and 1.4 million genetic variants also confirmed that no common genetic variant could predict the response to antidepressant treatment.

Source: King’s College London, Institute of Psychiatry, October 18, 2012.

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