Diagnosis of clinical depression, known as major depressive disorder (MDD), is based on a patient's subjective reported symptoms. Objective early diagnosis could help with more targeted treatment, as well as better outcomes in later life, but there is no laboratory test currently available. A biomarker panel from Northwestern University Feinberg School of Medicine could change all of that.
Depression is most commonly seen in people in their twenties. However, it can begin much earlier and have a huge effect on schoolwork and relationships. In teens, its symptoms can blur with the normal mood changes of adolescence and can also overlap with other physical and mental illnesses, thus making it hard to diagnose.
To find an answer, the researchers started by looking at blood transcriptomic profiles in rat models of depression. The transcriptome is the sum of all the RNA molecules produced in the cell, and it shows changes in the gene sequence, as well as changes caused by the environment, such as stress (epigenetic changes).
Once the researchers had potential biomarkers from the animal models, they used these to screen the blood of 15 to 19-year-olds with untreated MDD or without depression, and refined the biomarker panel to a selection that could be used to spot the differences between the two groups. These biomarkers could also pick out those teenagers with MDD with anxiety, or with maltreatment. According to the researchers, this is the first biomarker test to be able to distinguish between subtypes.
"Right now depression is treated with a blunt instrument," said Eva Redei, a professor of psychiatry and behavioral sciences at the Feinberg School of Medicine and lead investigator of the study, published in Translational Psychiatry. "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."
Dr. Sidney Kennedy, a psychiatrist at the University of Toronto, said Redei's study was the first to use messenger molecules as biological signposts for depression, according to the Los Angeles Times. As other efforts to find biomarkers mature--including costly brain scans and genetic analyses--those could refine and strengthen a blood test to screen large populations, he said. "There is merit in this work," he added.
Treatments for depression are not always effective. But, in addition to pointing the way to a blood test to tailor therapy to individuals, these results could also help researchers find new targets for treatment. However, it is still early and depression is a complex disease with genetic and environmental influences, and so there is a lot more work to do. Dr. Adelaide Robb, a child-and-adolescent psychiatrist at the Children's National Medical Center in Washington, D.C., was measured in her response, saying it was too early to consider the "problem solved," according to TIME Healthland. "Taking something from an animal model and saying it means something in people is making a big leap," she explained. "A finding among 14 is not the same as saying something is present in 1,000 people."