Researchers have developed a blood test that can diagnose depression in teens, a step they hope will lead to a better way to identify the disorder in young people. At present diagnosing depression depends entirely on a patient's willingness to report symptoms. For teens, the diagnosis is particularly challenging, given the natural emotional ups and downs of adolescence.
“Teenagers are extraordinarily vulnerable to depression,” said Eva Redei, author of the study and a professor of psychiatry and behavioural medicine at the Northwestern Feinberg School of Medicine in Chicago. “And there are no objective, biological measures for evaluating them for depression.” “Right now depression is treated with a blunt instrument,” Redei said in a written statement. “It's like treating type 1 diabetes and type 2 diabetes exactly the same way. We need to do better.”
In the new study published in the journal Translational Psychiatry, Redei and her team developed a test that looks for markers in the blood of teens with major depressive disorder. By studying rats that had genetic and environmental predispositions for depression, the researchers were able to pinpoint 26 markers of major depression. They looked for these markers in the blood of 28 human teenagers, ages 15 to 19, half with depression and half without. They found that 11 of the markers showed up in the depressed teens but not in teens without depression. They were also able to distinguish different subtypes of depression, successfully identifying teens who suffered from depression alone and depression combined with anxiety disorders. “The uniqueness of this study is that we showed that it can be done. The technology is available to make this diagnosis,” Redei said.
According to the National Institute of Mental Health, 11 percent of 13- to 18-year-olds develop major depression at some point in their adolescence. Reports from the Substance Abuse and Mental Health Services Administration are slightly lower – in 2008, 8.3 percent of 12- to 17-year-olds dealt with depression. The disorder puts teens at greater risk for other health dangers, including substance abuse, physical illness and suicide. Also, when depression begins earlier in life, the chances that it will persist and perhaps worsen in adulthood are great.
In February, researchers at Massachusetts General Hospital analyzed blood from depressed adults and found that the levels of nine biomarkers differed from those without the disorder. Redei said her test is different because it identifies blood markers not previously linked to depression.
The study authors say they are hopeful that a blood test diagnosis for depression will help more teens get the treatment they need.
Dr. Michael Thase, a professor of psychiatry at the University of Pennsylvania Perelman School of Medicine, said even though it was tested on teens, the blood test might help adults. “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,” Thase told MSNBC. He was not involved in the research. “That could potentially lead to new treatments.”
Dr. Carol Bernstein, an associate professor of psychiatry at New York University Langone Medical Center, said biologic testing doesn't get at the complex interactions of genes, biology and environment involved in depression. “I think people are looking for a magic bullet, a single answer. But these disorders are much too complicated,” she said. “But certainly the more tools we have the better.”
Dr. Alexander B. Niculescu, III, associate professor of psychiatry and medical neuroscience at Indiana University School of Medicine, downplayed the study's implications, telling WebMD, “We need to be careful not to jump to conclusions based on a small number of study participants.” adding blood markers for depression may vary among a larger population.
Redei said developing a blood test is important not just for diagnosing patients, but also reducing the stigma associated with having depression. “The fact that there are no objective biological measures for depression is probably a major contributor to the stigma,” Redei said.
“Once it's a medically proven objectively measured illness, the stigma sooner or later has to diminish or even disappear.”
Redei and her colleagues are currently testing how well the blood test works in adults with depression.
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