Blood test looks promising in diagnosing depression

A preliminary study finds certain biological markers in the blood of teens with depression that are absent in healthy counterparts. It could lead to the first diagnostic testing for depression, The Los Angeles Times reports.

Even among psychiatric disorders, depression is a difficult disease to diagnose. Its causes remain a mystery, its symptoms can't be defined with precision, and treatments are spotty at best.

But that may soon change. Scientists are looking for ways to identify patients with depression as reliably as they diagnose cardiovascular disease, diabetes and cancer. A new study takes a significant, though preliminary, step in that direction by demonstrating that a simple blood test can distinguish between people who are depressed and those who are not.

The study, published online Tuesday in the journal Translational Psychiatry, offers hope that doctors can do a better job of helping adolescents whose mood difficulties go beyond those of typical teens, and whose lifelong prospects could be greatly improved by early treatment. What's more, by using objective data to diagnose mental pain, researchers hope to remove the stigma that often prevents patients from reaching out to doctors.

The study drew responses of praise and caution from other researchers seeking better ways to diagnose and treat major depressive disorder.

The current study focused on teens and "early onset" depression, but the researchers said they hoped to include adults in future testing.