Blood Tests Diagnose Depression?

New blood tests to diagnose depression may lead to better treatment, less stigma

Diagnosing teenage depression the way it’s done now — by letting teens take the Beck Depression Inventory (BDI) and asking them to describe their own symptoms, and then relying on psychiatrists to interprete these — can be tricky since mood swings are normal during the adolescent years.

But diagnosing depression in teenagers is urgent because these youngsters are highly vulnerable to the mental disorder: Teenage years are the prime time for depression to start and rates of major depressive disorders jump from two to four percent in pre-adolescent kids to 10 to 20 percent by late adolescence. On top of that, untreated depression in teens puts these children at greater risk for suicide — and for a lifetime of social difficulties, substance abuse and physical illness.

That’s why it’s so important to get an early and accurate diagnosis, say researchers from the Northwestern University Feinberg School of Medicine in Chicago, Illinois.

“This is the generation, the age group that needs the most help,” Dr. Eva Redei, a professor of psychiatry and behavioral sciences at the NU Feinberg School of Medicine tells WebMD. “They are our next generation and an increased percentage of them are getting seriously depressed and in major trouble,” Dr. Redei continues.

According to estimates cited in a new study led by Dr. Redei, major depressive disorders may affect up to 20 percent of the population of adolescents and young adults in the United States. This is why the researchers are hoping to develop a way of diagnosing depression that’s as easy and accurate as diagnosing high cholesterol or diabetes.

Their new study, published in the April 17 issue of the journal Translational Psychiatry, the researchers describe a new blood test they developed to diagnose depression in teenagers and to distinguish different types of this mental illness. Doctors could one day use these blood tests to diagnose patients instead of relying on subjective interviews, says Dr. Redei in an interview with The Toronto Star.

Right now, diagnosis relies on the patient’s ability to recount their symptoms and the doctor’s ability and training to interpret these.

The new study shows that, compared to their non-depressed peers, teenagers suffering from depression have different levels of specific genetic blood markers. Aside from this, it’s also the first time that subtypes of depression have been diagnosed from a blood test — distinguishing between teens with major depression and those with major depression combined with anxiety disorder.

“Right now depression is treated with a blunt instrument,” Dr. Redei says in a written statement. “It’s like treating type 1 diabetes and type 2 diabetes exactly the same way. We need to do better.”

“This is the first significant step for us to understand which treatment will be most effective for an individual patient,” she adds. “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.”

Using markers to diagnose depression
For their study, Dr. Redei and her colleagues tested the blood of 28 teens from Ohio who were 15 to 19 years old. Half of these teens (14 individuals) had been diagnosed as depressed but not treated; the others weren’t depressed.

The depressed teens in the study were patients of Dr. Kathleen Pajer of the Research Institute of Nationwide Children’s Hospital in Columbus, Ohio. Dr. Pajer is also a co-first author of the new study.

Researchers took blood samples from the youngsters and checked these for 26 genetic blood markers that indicated depression in rats in previous research. When they compared the samples from the depressed teens with those from non-depressed ones, the researchers identified 11 markers that may be tied to depression — and discovered that levels of these markers were lower in depressed teens.