How trauma spreads through social networks:
A team of researchers led by Virginia Tech’s Michael Hughes surveyed 4,639 of the school’s students three to four months after the tragedy. The researchers found 15.4 percent were experiencing high levels of post-traumatic stress symptoms (which can include flashbacks, nightmares, difficulty concentrating, agitation or emotional detachment). Those with the highest odds of experiencing PTSD symptoms were students who knew someone who was killed or injured in the attack, along with those who were unable "to confirm the safety of friends" as the events unfolded.
The Dish 