While Veterans’ Day reminds us to honor the brave soldiers who fought so hard for our country, lets not forget that many of them are still fighting in a different way today. A new study from the University of California, San Diego, suggests that veterans who suffered physical injuries or developed post-traumatic stress disorder after combat in Iraq or Afghanistan may suffer recurrent headaches.

According to the study, which surveyed 308 veterans, those who had suffered combat injuries were at greater risk of developing migraine headaches. At the same time, those who screened positive for post-traumatic stress disorder (PTSD) had elevated rates of both migraine and tension-type headaches. Overall, vets with only physical injuries had more than twice the risk of recurrent headaches as those without such injuries. The risk was four times higher among veterans with PTSD than those without it.

Moreover, researchers found that physical injuries made veterans more prone to migraine only, while PTSD was linked to both migraines and tension-type headaches. The study authors write that PTSD may be linked to headaches because psychological stress can trigger headaches through the body’s natural physiological responses to stress.

No matter what the cause of headaches in veterans, however, the researchers say that this link between wartime injury and recurrent headaches suggests that veterans could benefit from comprehensive assessments of their physical, mental and emotional health in order to find the best treatment options for them.