Northwestern Medicine scientists in Chicago have developed a blood test to diagnose major depression in adults, marking the first such test to objectively and scientifically diagnose the disorder.
The test measures the levels of nine blood markers to both identify depression and predict whether the patient will benefit from cognitive behavioral therapy. Doctors hope the test will provide more effective, individualized therapy.
“This test brings mental health diagnosis into the 21st century and offers the first personalized medicine approach to people suffering from depression,” said Eva Redei, a professor of psychiatry and behavioral sciences at Northwestern University Feinberg School of Medicine who developed the test.
Redei, a co-lead author of the study being published Tuesday in Translational Psychiatry, said this marks a breakthrough, indicating that a blood-based laboratory test, similar to diagnosing high blood pressure, can diagnose depression.
Northwestern said scientists have worked for decades to find a biological diagnostic test for major depression and noted the current method of diagnosis is subjective and based on symptoms such as poor mood, fatigue and change in appetite.
The current diagnosis, Redei said, relies on patients reporting those subjective symptoms and the physician’s ability to interpret them. "But depressed patients frequently underreport or inadequately describe their symptoms," the hospital said.
“Mental health has been where medicine was 100 years ago when physicians diagnosed illnesses or disorders based on symptoms,” co-lead author David Mohr said. “This study brings us much closer to having laboratory tests that can be used in diagnosis and treatment selection.”
Mohr said scientists know drug therapy and psychotherapy aren't effective for everyone, and this test helps determine whom those options fit best.
“We know combined therapies are more effective than either alone, but maybe by combining therapies we are using a scattershot approach," he said. "Having a blood test would allow us to better target treatment to individuals.”
Northwestern says major depressive disorder affects 6.7 percent of U.S. adults in a year and is on the rise. An estimated 12.5 percent of patients in primary care have major depression, according to the hospital, but only about half of those cases are diagnosed. And with the current methods, diagnosis takes between two and 40 months.
Redei said they plan to test the study's results in a larger population and find out if it can differentiate between major depression and bipolar depression.