April 17, 2012 at 10:00 AM ET
A simple blood test may one day be all that’s needed to help parents figure out whether a child is suffering from clinical depression or normal teenage angst, a new study suggests.
In a pilot study of 28 adolescents, scientists showed that teenage depression could be diagnosed through a panel of 11 genetic markers, according to a report published in the journal Translational Psychiatry.
If the results are confirmed in larger trials, doctors may one day be able to screen for depression just as they do for diabetes, says study co-author Eva Redei, the David Lawrence Stein professor of psychiatric diseases affecting children and adolescents at Northwestern University's Feinberg School of Medicine.
This new research could help not only teens, but also adults suffering from depression, says Dr. Michael Thase, a professor of psychiatry at the Perelman School of Medicine at the University of Pennsylvania.
“This is very interesting early research that could point to the development of not just biomarkers, but also help with the identification of new genes that are involved with the expression of this common illness,” he says. “And that could potentially lead to new treatments.”
With no actual test, diagnosis of depression is currently subjective and depends on a person's ability to identify and describe symptoms. This is especially difficult for teens who may be particularly out of touch with what's going on.
Researchers developed their test by first studying rats specially bred to model human depression. While rats don’t experience all the symptoms of depression, they do show many of the same signs.
“They huddle together,” says Redei. “They don’t move around a lot. They aren’t much interested in playing. They’re less interested in food than normal rats. And they don’t sleep well.”
Intriguingly, the "depressed" rats also respond well to certain antidepressants, says Redei.
"In reality, depression affects our ancient brains as much as our new brain,” she says. “And the ancient brain is the same in humans as it is in rats.”
Severe depression is thought to be caused by a combination of environmental and complicated genetic factors, she explains, and given the right genetics, can be kicked off by “any kind of environmental challenge such as trauma or life stresses."
To see how the depressive brain reacts to environmental triggers, Redei and her colleagues looked at differences in the way normal rats and depression-model rats behaved in response to stress. They pulled blood samples from all the rats and found a host of markers that differed between the two groups.
In the second part of their study, the researchers examined blood from 14 depressed and 14 healthy teens, looking at the levels of 26 markers that had been identified in the depression-model rats.
They found that 11 of those markers, taken together, accurately predicted which teens were clinically depressed.
Thase, of the University of Pennsylvania, says further research might be a boon to diagnosing both teen -- and adult -- depression.
"Now you would want to see if they get the same results with older people," he says. "Or does it have something to do specifically with early onset depression?"