Depression is a psychiatric disorder widespread in western countries. Currently, the diagnosis of this disease is based on non-specific symptoms such as low mood, fatigue, lack of appetite, which also occur in numerous other mental or physical illnesses.

D. C. Mohr, Northeastern University, Chicago, USA, and colleagues developed a blood test to accurately diagnose depression in adults. By conducting a study on 32 depressed patients and 32 healthy control subjects, the researchers discovered that nine messenger RNA markers were present at high concentrations in the blood of depressed patients but at very low levels in healthy controls. The concentration of these messenger RNA markers also predicted the patients’ response to therapies as they decreased in patients who were no longer depressed after 18 months of therapy.

Determining the blood concentration of these molecules may, therefore, provide an accurate diagnosis of depression and a means of monitoring the response to therapy.

• Blood transcriptomic biomarkers in adult primary care patients with major depressive disorder undergoing cognitive behavioral therapy,
  E. E. Redei, B. M. Andrus, M. J. Kwasny, J. Seok, X. Cai, J. Ho, D. C. Mohr,
  Transl. Psychiatr. 2014, 4, e442.
  DOI: 10.1038/tp.2014.66