CHICAGO (CBS) — A Chicago neuroscientist says she has developed the first blood test to diagnose depression in teenagers.

As WBBM Newsradio’s Regine Schlesinger reports, until now, there has been no objective way to diagnose depression. It has been up to patients to recognize the mental disorder themselves or for doctors to notice symptoms.

Diagnosing teenagers with severe depression is especially difficult because of the mood swings that often are normal in adolescents and teens. And if they do not report their own symptoms, they will go undiagnosed and untreated.

LISTEN: WBBM Newsradio’s Regine Schlesinger reports

But now, Dr. Eva Redei, a professor of psychiatry at Northwestern’s Feinberg School of Medicine, says she has developed the first blood test that can provide an objective diagnosis. It is a breakthrough that tests for a specific set of biomarkers in the blood.

Redei says it will also help relieve the stigma associated with the diagnosis.

“If there is something that can be measured in your blood, then it’s not about how weak I am. It’s not about, ‘There’s something wrong with my personality,’” Redei said.

The blood test is also the first to identify specific sub-types of depression, offering the promise of tailoring treatment for individual patients.