Blood Test Can Diagnose Teen Depression

A new blood test could diagnose depression in teens. The co-author of a new study tells us how her research could cut down the disease's social stigma, on Chicago Tonight at 7:00 pm.

The test examines the levels of genetic markers, or chemicals, in teens' blood. Patients would be diagnosed as depressed if those levels were abnormally high or low.

Northwestern Medicine psychiatry and behavioral sciences professor, Eva Redei, was the study's lead investigator, and says the test also can diagnose certain subtypes of depression, such as depression with anxiety disorder.

The study focused on teens, Redei says, because teen depression can be more dangerous than adult-onset depression.

"The scientific reason to test teens is that I firmly believe this is the most vulnerable population," she said. "It's when life decisions are being made, and so my greatest worry is really for them."

Depressed teens have a poorer prognosis than depressed adults because some of their symptoms are chalked up to normal teen behavior, according to Angelos Halaris, medical director of adult psychiatry at Loyola University.

"Teenagers can exhibit truancy, running away, being belligerent or rebellious with their parents, and some people say, 'It's typical teen behavior, it's no big deal,'" said Halaris, who was not connected to the Northwestern study. "That's wrong. It could be manifestations of an underlying depressive illness that has not yet formed into an adult version that we can more easily recognize."

An objective diagnostic tool for depression would help identify which teens are depressed before the disease advances to its mature form, he says.

Because teen depression can often go unrecognized and thus untreated, Halaris said, it can progress into more serious forms. The impulsivity of teens can also lead them to respond to their depression with substance abuse or suicide more readily than adults, he said.

Redei and her team examined blood from 14 depressed teens and 14 non-depressed teens. The researchers found 11 genetic markers differentiated between the two groups. 

A similar test from researchers at Massachusetts General Hospital linked depression to genetic markers in February. But Redei says her test differs because the Boston test looked for markers already linked to depression, such as neuron development or stress response.

"Their approach was to take existing knowledge and see if it can help diagnose depressed patients," Redei said. "We said, 'Let's take an unbiased approach.'"

The test is currently being tested for adults, and while Redei says she can't comment on the ongoing study, there's "nothing to say it wouldn't work" in adults.

The test could improve depression treatment by helping psychiatrists identify what antidepressant to prescribe.

"[Diagnostics] is a blunt instrument because there's no exact way to identify which patient should be treated with what kind of antidepressant," Redei said. "Right now, psychiatrists try one, and if it doesn't work, they move on to another. It's possible antidepressants would be more successful if the right one is chosen for a patient."

Redei also hopes creating an objective test for depression will cut down on its social stigma. Many view depression as something that can be willed away, she says.

"You can hear it everywhere: 'Just get a better attitude,' or 'Be positive,' or 'Just snap out of it.'," she said. "We even call it a mental illness. We don't just say it's an illness like any other illness."

Halaris, from Loyola University, says he also sees patients ashamed of their depression.

"The stigma is quite pervasive throughout society," he said. "Having a biological test is gong to help us a lot to prove to society that depressive illness is a serious biological illness."