Blood test provides first objective diagnosis of depression in adults

Researchers have developed a blood test that can diagnose depression in adults (Photo: Shutterstock)

Diagnosing depression can be a difficult task, currently relying on patients reporting symptoms – something those suffering depression don't always do – and doctors correctly interpreting them – which isn't easy as the symptoms are non-specific. Now researchers have developed a blood test to diagnose depression in adults, providing the first objective, scientific diagnosis for the condition.

Earlier this year, a team from the University of Vienna revealed that measuring the levels of serotonin in the blood showed promise for potentially diagnosing depression through a blood test. And in 2012, Eva Redei, a professor of psychiatry and behavioral sciences at Northwestern University Feinberg School of Medicine developed a blood test to diagnose depression in adolescents that involved looking at 26 genetic blood markers.

Building on that research, Redei and a team at Northwestern have developed a blood test to diagnose depression in adults. In the team's study, they found that the levels of nine RNA blood markers in 32 patients, who were aged from 21 to 79 and had been independently diagnosed with depression after clinical interviews, were significantly different than levels in 32 non-depressed controls in the same age range.

After 18 weeks of therapy, both face-to-face and over the phone, changes in the levels of the markers allowed the researchers to differentiate between patients who had responded positively and were no longer depressed and those that remained depressed. The researchers say this is the first time a biological indicator has been used to indicate the success of cognitive behavioral therapy in adults suffering depression.

Additionally, examining the baseline levels of the nine markers in patients who subsequently recovered from depression after therapy allowed the researchers to identify a "fingerprint" from the blood test that would indicate which patients would benefit from cognitive behavioral therapy. This fingerprint didn't appear in depressed patients who didn't improve with the therapy.

Furthermore, the researchers found that the concentration levels of three of the nine RNA markers remained different in depressed patients and non-depressed controls, even if the depressed patients achieved remission after therapy. They say this suggests these three markers could indicate a vulnerability to depression.

"These three markers move us towards the ultimate goal of identifying predisposition to depression, even in the absence of a current depressive episode," said Redei.

"Being aware of people who are more susceptible to recurring depression allows us to monitor them more closely," added co-lead author David Mohr, a professor of preventive medicine and director of the Center for Behavioral Intervention Technologies at Feinberg. "They can consider a maintenance dose of antidepressants or continued psychotherapy to diminish the severity of a future episode or prolong the intervals between episodes."

Redei now plans to test the results in a larger population and will also examine whether the test can be used to differentiate between major depression and bipolar depression.

In the video below, Redei gives an overview of the research, which is published in the journal Translational Psychiatry.

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