Northwestern University researchers created the first blood test to diagnose major depression in adults.
The test identifies depression by measuring the levels of nine RNA blood markers, which are messengers that interpret DNA genetic codes and carry out their instructions. The blood test could also predicts which patients will benefit from cognitive behavioral therapy based on how some of these marker s behave.
The test pinpointed the success of current depression therapies because the levels of markers changed in patients who underwent the treatments for 18 weeks or longer and reported no longer being depressed.
"This clearly indicates that you can have a blood-based laboratory test for depression, providing a scientific diagnosis in the same way someone is diagnosed with high blood pressure or high cholesterol," said Eva Redei, PhD, who developed the test and is a professor of Psychiatry and Behavioral Sciences at Northwestern University Feinberg School of Medicine. "This test brings mental health diagnosis into the 21st century and offers the first personalized medicine approach to people suffering from depression."
To make their findings the researchers looked at 32 patients between the ages of 21 and 79 who had been diagnosed with depression in a clinical interview and 32 non-depressed controls. Some of the patients had been on antidepressants but were still experiencing symptoms. The researchers found nine RNA blood markers with levels significantly different in the depressed individuals. After 18 weeks of cognitive behavioral therapy the markers could differentiate between who people who had responded positively and those who were still depressed.
The current method of diagnosing depression is usually subjectively based off of symptoms such as "poor mood, fatigue and change in appetite," which can be linked to other mental problems. These diagnoses also rely on the ability of the patient to accurately report their symptoms.
"Mental health has been where medicine was 100 years ago when physicians diagnosed illnesses or disorders based on symptoms," said co-lead author David Mohr, PhD, a professor of Preventive Medicine and director of the Center for Behavioral Intervention Technologies at Feinberg. "This study brings us much closer to having laboratory tests that can be used in diagnosis and treatment selection."
This new blood test will allow research to determine which treatments will work most effectively for each patient.
"Currently we know drug therapy is effective but not for everybody and psychotherapy is effective but not for everybody," Mohr said. "We know combined therapies are more effective than either alone but maybe by combining therapies we are using a scattershot approach. Having a blood test would allow us to better target treatment to individuals."
The findings were published Sept. 17 in the journal Translational Psychiatry.
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