Depression: It's in Your Blood, Can Be Tested Researchers develop test that can look for key markers By Kevin Spak, Newser Staff Posted Apr 18, 2012 12:32 PM CDT 0 comments Comments Depression could be diagnosable via blood test. (Shuttestock) (Newser) – Soon, you may not have to sit down with a therapist to know if you have depression. A team of researchers has developed a blood test that can identify the markers of major depressive disorder in teens, they say in a study published yesterday in Translational Psychiatry. The researchers focused on teens because they are especially vulnerable to depression, and may be reluctant to report symptoms, but they hope to include adults in future tests. "Once you have a measurable index of an illness, it's very difficult to say, 'Just pull yourself together,' or 'Get over it,'" lead researcher Eva Redei tells the LA Times. They created the test by stressing out lab rats, and identifying "messenger molecules" in their blood that was not in healthy rats' blood. They then tested teenagers, and found that the same molecules were present in those diagnosed with depression. "We showed that it can be done," Redei tells ABC. "The technology is available."