Post traumatic stress disorder could soon be diagnosed with simple blood test after scientists found crucial genetic changes in soldiers suffering from trauma after serving in Afghanistan.

PTSD is an anxiety disorder caused by stressful or frightening events which can cause flashbacks, nightmares, depression, sleep problems and guilt.

Until now it could only be diagnosed through self-reported symptoms, which many victims, particularly servicemen, were reluctant to disclose.

But scientists at the University of Maastricht discovered crucial differences in the microRNA molecules of soldiers who had served time in Afghanistan.

Unlike DNA which provides the genetic code for functions in the body, microRNA regulates how active those genes are.