Millions of Americans are affected by depression, but only 39% of people with the illness contacted a mental health professional in the previous year, according to the Centers for Disease Control and Prevention. Two promising new blood tests, though, could reduce the stigma associated with depression, along with its reputation as being “only in the head.” In the first study, published in the journal Translational Psychiatry, researchers identified 11 biological markers—chemicals—in the bloodstream that could be used to diagnose early-onset depression in teenagers. This type of depression occurs in people before the age of 25, and tends to have a worse outcome than depression that starts later in life. Left untreated, it can cause problems well into adulthood. By measuring the 11 markers in samples of blood taken from teens, researchers were able to differentiate between teenagers with depression and those without. They also identified 18 markers that could be used tell apart teenagers with depression and those with both depression and anxiety. The second study, published in Molecular Psychiatry, took a similar approach with adult-onset depression. Researchers identified nine markers that could be used to determine the likelihood that someone has depression. Using blood samples, researchers assigned a “score” that could identify depressed and non-depressed people. Both tests, if successful with larger studies, would make it easier to diagnose depression. Currently, psychiatrists rely upon patients’ reports of their own symptoms, which may not always be accurate. The tests, however, are not intended to replace a psychiatrist’s evaluation, only to add more concrete information. Primary care physicians could easily order the blood tests for patients, and refer them to mental health professionals, if needed. By reducing the stigma associated with depression, this could increase the number of people who seek out treatment.