Post-Traumatic Stress Disorder (PTSD) is thought to affect up to one in three people who have undergone traumatic experiences, particularly those who have experienced active military service, torture, and violent assaults. Yet because it is a psychological condition, and often relies on individuals themselves seeking help, it frequently goes unreported.

This is of particular concern for soldiers, who may not want to admit to having mental issues coping with the stress after they return from war. Now, The Telegraph reports researchers may have uncovered a form of epigenetic changes in those who have PTSD, which could potentially result in a blood test that could diagnose people most at risk, even before symptoms have manifested.

The work revolves around a tiny molecule known as microRNA. Its usual function is to float around within the cell regulating gene expression, usually through blocking the translation of messenger RNA (mRNA) into protein. In the pilot study, carried out by the University of Maastricht, and being presented at the European College of Neuropharmacology in Paris this week, researchers found that people who have been diagnosed with PTSD have physical differences in some of their microRNA.

The scientists looked at three groups of adults: soldiers who had not seen service, soldiers who had and experienced trauma but did not develop PTSD, and finally Afghanistan war veterans who had also suffered trauma but had also developed PTSD.

They discovered that when comparing those soldiers with PTSD with those who had not seen active service there were up to 40 differences in the microRNA detectable. Yet between those who had served but have not been diagnosed with PTSD and those with it, there were 27 detectable differences. This, they argue could lead the way for tests that could register this difference.

“Most of our stressful experiences don’t leave a long-lasting psychological scar,” lead author Dr Laurence de Nijs told The Telegraph. “However, for some people who experience chronic severe stress or really terrible traumatic events, the stress does not go away. They are stuck with it and the body’s stress response is stuck in ‘on’ mode. This can lead to the development of mental illness such as PTSD.”

The argument here is that because these microRNA molecules can also be found circulating in our blood stream, a test could be developed to pick up on them, and see if the markers are there for whether or not a patient may have an increased risk of developing PTSD.

This test, however, if it could ever be developed, would have to be incredibly sensitive. While theoretically it could be possible, and would be a massive help in the diagnosing and treating of PTSD, so far it is not possible.