Post-traumatic stress disorder can be difficult to diagnose because its symptoms vary considerably, the researchers explained and many of those symptoms, such as memory loss and attention problems which are similar to those of a concussion. In the small study, the researchers said they found that over-connected brain circuits in soldiers with post-traumatic stress disorder made them more attuned to angry faces than happy faces. The heightened perception of anger in post-traumatic stress disorder is driven by complicated brain circuitry where the mechanism of communication among a number of key regions that control fear and emotion is over-connected. Potentially, new findings can tell us about the heightened threat perception people with post-traumatic stress disorder experience known as hyperarousal and allow us to develop novel ways of assessing treatment and determining when a soldier is ready to return to deployment. This may be why emotional responses are so immediate and automatic, and why threatening faces are such a trigger. These findings emphasize the challenges of living with this post-traumatic stress disorder and treating post-traumatic stress disorder.