New Research Could Lead to Blood Test for Depression

A team led by Northwestern psychiatry professor Eva Redei has published a research study in the journal Translational Psychiatry today, entitled “Blood transcriptomic biomarkers in adult primary care patients with major depressive disorder undergoing cognitive behavioral therapy”. The abstract states that this research “could increase the diagnostic accuracy of major depressive disorders (MDDs), identify factors that characterize patients and promote individualized therapy”.

Popular science summaries of Redei’s paper have appeared at Time, Russia Today, CTV News, The Independent and elsewhere.

The study tracked nine RNA blood markers in a group of depression patients and a control group of non-depressed people. Researchers then continued to test the depressed subjects as they received cognitive behavioral therapy over 18 weeks. Alice Park at Time explains:

About 60% of the patients did not experience another depressive episode during the study period’s 18 weeks. But 40% of them did, and they showed differences in three gene products that were measured in the blood.

In addition, the team also found three markers among the original nine that remained different even among the depressed patients who benefited from CBT, and the controls. That suggests these markers could be harbingers of a person’s vulnerability to the mood disorder. In other words, they could be predisposing factors that make depression more likely in the face of stress or anxiety or trauma. Of the remaining six markers in the panel, Redei says they could be useful measures of the changing state of a patient’s depression, similar to fluctuating levels of cholesterol or blood pressure, and they could be a helpful gauge for doctors in figure out how much treatment or medication a patient might need.

Blood testing based on this research could improve early detection of a genetic predisposition toward depression. The CTV News article quotes Redei, “These three markers move us toward the ultimate goal of identifying predisposition to depression, even in the absence of a current depressive episode.”

Blood testing could also help distinguish different types of depression, improve diagnosis of a patient’s current condition, and help recommend particular treatments likely to help particular patients. Again from Marlene Leung at CTV:

The current method of diagnosing depression is based on reporting and assessing non-specific symptoms including poor mood, fatigue and changes in appetite.

A diagnosis is based on the patient’s ability to report their own symptoms, as well as the doctor’s ability to interpret them. This can be problematic, as many depressed patients underreport their symptoms or can’t adequately describe them, the researchers said.

“Mental health has been where medicine was 100 years ago when physicians diagnosed illnesses or disorders based on symptoms,” [study co-author David] Mohr said in the statement. “This study brings us much closer to having laboratory tests that can be used in diagnosis and treatment selection.”

As a longtime depression sufferer, this account rings true. How often have you tried to describe your “current mood” to a therapist, or hesitated over “somewhat” vs “very” on a depression symptom checklist, and felt frustrated by the fuzziness of this method? (No disrespect intended toward the developers of the checklist method, which was light years better than what came before.)

Useful widespread application of this blood marker research is likely years away, but reading about scientific advances fills me with hope. Understanding and treatment of depression has improved greatly over the past few decades, and that process is bound to continue.

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