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04/19/2012 05:37 pm ET Updated Apr 19, 2012

Teen Depression Can Be Diagnosed With New Blood Test, Northwestern University Says

Northwestern Medicine scientist Eva Redei has developed the first blood test to diagnose major depression in teens -- a breakthrough that allows for scientific and objective diagnosis over current subjective methods.

Physicians have relied upon a patient’s ability to recount symptoms, which is tricky among teens who are both highly vulnerable to depression and less able to express their symptoms changes during this age period.

The estimated rates of major depressive disorder jump from 2 to 4 percent in pre-adolescent children to 10 to 20 percent by late adolescence. Early onset of major depression in teens has a poorer prognosis than when it starts in adulthood. Untreated teens with this disease experience increases in substance abuse, social maladjustment, physical illness and suicide, according to Redei.

Dr. Andrew Leuchter, a UCLA psychiatrist, told the LA Times, "This is definitely an encouraging study."

Redei hopes that an objective approach to diagnosing depression will affect how its treated too. After teens were diagnosed using the test, many parents chose not to treat them.

“Everybody, including parents, are wary of treatment, and there remains a social stigma around depression, which in the peer-pressured world of teenagers is even more devastating,” Redei said. “Once you can objectively diagnose depression as you would hypertension or diabetes, the stigma will likely disappear.”

The blood test is also the first to identify subtypes of depression, according to Northwestern. It can allegedly distinguish between teens with major depression and those with major depression combined with anxiety disorder. This is the first evidence that it’s possible to diagnose subtypes of depression from blood, raising the hope for tailoring care to the different types.

“Right now depression is treated with a blunt instrument,” Redei, who published her finding in Translational Psychiatry this week, said. “It’s like treating type 1 diabetes and type 2 diabetes exactly the same way. We need to do better for these kids.

“This is the first significant step for us to understand which treatment will be most effective for an individual patient,” added Redei. “Without an objective diagnosis, it’s very difficult to make that assessment. The early diagnosis and specific classification of early major depression could lead to a larger repertoire of more effective treatments and enhanced individualized care.”

The study subjects included 14 adolescents with major depression who had not been clinically treated and 14 non-depressed adolescents, all between 15 to 19 years old.

Redei first isolated and identified the 26 blood markers for depression and anxiety based on decades of research with severely depressed and anxious rats, known to mirror many behavioral and physiological abnormalities found in patients with major depression and anxiety.

The tests found 11 markers showed up in depressed teens blood and were absent in teens without depression.

“These 11 genes are probably the tip of the iceberg because depression is a complex illness,” Redei said. “But it’s an entree into a much bigger phenomenon that has to be explored. It clearly indicates we can diagnose from blood and create a blood diagnosis test for depression.”

But not all are sold that this objectivity and seemingly-solid conclusion is the best way to diagnose depression.

In the Daily Beast, Alexander Niculescu, who conducts similar research at the Indiana University School of Medicine, said, “I think their results are not solid. I think the approach overall that they are taking is solid, but I’m biased because we’ve taken that same approach in a more comprehensive fashion.”

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