Survivors of a terror attack may be more likely to begin having frequent migraine and tension headaches after the attack, according to a study published in the December online issue of Neurology. Researchers studied the teenage survivors of a 2011 terror attack in Norway.

The 358 teenage survivors of the attack were invited to participate in the study. All participants were then interviewed about their headache frequency. The results of the 213 participants were compared to more than 1704 similarly aged people who had not experienced a terror attack.

The teenagers who survived the attack were 4 times more likely to have migraine and 3 times more likely to have frequent tension headaches.

“We know a lot about the psychological effects of terror attacks … but we didn’t know much about the physical effects of these violent incidents,” said Synne Øien Stensland, MD, PhD, of the Norwegian Centre for Violence and Traumatic Stress Studies in Oslo, according to Science Daily.

Among the females, 73% of those exposed to the attacks had recurring headaches. This is compared to 37% of those not exposed. For the males, 41% of those exposed had headaches compared to 19% of those not exposed.

“We suspected that headache would increase for terror survivors, and the increase was over and above what might be expected based on psychological distress and other risk factors,” said Stensland, the lead author of the study. She added that this study suggests a need to find ways to do more to help people in the immediate aftermath of similar terror attacks.

“Our study shows that a single highly stressful event may lead to ongoing suffering with frequent migraines and other headaches, which can be disabling when they keep people from their work or school activities.”