New blood test could help tailor antidepressant treatment to individual

The initial study is small, but the results are promising. Researchers from King’s College London have developed a blood test that could identify accurate antidepressant treatment for each individual. If the test shows signs of inflammation, the patient needs more aggressive treatment from the outset.

Finding the right antidepressant is presently a matter of trial and error, which means that about half the time the first antidepressant given fails to work. Not many tools exist for the treatment of depression and the development of individualized medication plans.

The new blood test, which is described in the International Journal of Neuropsychopharmacology, is the result of years of investigation. The test looks for two compounds that are markers of inflammation: interleukin-1beta and macrophage migration inhibitory factor (MIF). In the study, individuals with high levels of those compounds are unlikely to respond to the commonly prescribed tricyclic and SSRI antidepressants.

In fact, the study found that above a certain threshold of inflammation patients had a 100 percent chance of not responding to antidepressant medication. Those with readings below that threshold could be “expected” to respond to the same treatments.

Lead researcher Prof. Carmine Pariante said a larger trial is needed, but the knowledge they gained from the small study, which involved 140 people with depression, could help tailor treatment to individuals. “About a third of patients might have these inflammatory markers and they would be people we might encourage to go on more aggressive treatment,” Pariante said.

Pariante suspects that the inflammation is a natural response by the body to stress, but the inflammation can interfere with the processes that are crucial for antidepressants to work. The team is now looking into whether given anti-inflammatory drugs along with the antidepressants would help. However, Pariante cautions that patients should not make changes to their medications or start taking anti-inflammatories without guidance from their doctor.