In one of the largest, and most detailed studies of its kind conducted to date, a team of researchers examined data from over 150,000 US war veterans and found eight specific genetic regions that seem to confer an increased risk of developing post-traumatic stress disorder (PTSD).

Around one in five soldiers returning home from war will suffer from some kind of PTSD. While new therapies to treat this debilitating disorder are on the horizon, it is still unclear exactly why some people are more at risk of developing PTSD than others.

In order to better understand what possible genetic propensity there could be for developing PTSD, the new study performed a genome-wide association analysis on data from 166,643 US war veterans. Eight specific genetic regions were significantly associated with PTSD and interestingly, these genetic regions are known to be related to brain regions regulating stress responses.

"The genes implicated in this study point to this region of the brain, and these types of neurons, as potentially involved in PTSD vulnerability," explains Murray Stein one of the research leads on the new study.

These genetic associations were only observed in the European American veteran cohort. The researchers hypothesize the lack of association in the African American cohort is possibly due to an underpowered cohort volume, with African American veterans comprising a little under 10 percent of the total dataset.

Some of the genetic regions highlighted by the study are related to a specific kind of neuron called striatal medium spinal neurons. These neurons are active in parts of the brain regulating reinforcement and aversion behaviors. Stein suggests this research directs future study toward ways to disrupt the activity in those parts of the brain that could influence the development of PTSD.

"Because we know something about the regulation of these neurons, we can test hypotheses about drugs that might be useful for PTSD, such as drugs that influence dopamine or GABA, both of which are regulatory of these types of neurons," says Stein.

The new research was published in the journal Nature Neuroscience.