Over 100 U.S. troops caught in the crossfires of an Iranian missile attack launched in retaliation for the killing of Maj. Gen. Qassem Soleimani, an extremist leader, have been diagnosed with brain damage.

Veterans groups, like the Veterans of Foreign Wars, and lawmakers, like Rep. Andy Kim (D-N.J.), have led the charge to educate people on how harmful these brain injuries can be, going way beyond headaches. 

“The first step in taking care of our service members and veterans is to take their injuries seriously,” Kim, who served in Afghanistan as a diplomat and adviser, wrote on Twitter. “I’ve talked to many veterans who said they felt pressure to minimize ‘invisible injuries’ and mental health problems,” he said.

“I stand with the Veterans of Foreign Wars who continue to call upon the President to fully recognize the dangers of Traumatic Brain Injuries and not dismiss them as headaches,” the congressman said in a separate tweet.

Since 2000, about 408,000 service members have been diagnosed with traumatic brain injury, according to Pentagon data.

Though many TBI’s manifest as minor concussions that require minimal recovery, they can be deadly. In 2015, there were 56,800 TBI-related deaths in the US, including 2,529 deaths among children, according to CDC data.

There was renewed focus on these injuries after President Donald Trump announced that “no Americans were harmed” after the January 8 attack. The Pentagon later confirmed several cases of mild traumatic brain injuries among U.S. military victims. The most recent number of confirmed cases was 109, and at least 29 troops have been sent back to the U.S. for additional treatment, suggesting their injuries could be more severe.

Various health and medical groups have spent years trying to educate the public about the seriousness of brain injuries, including concussions, according to Reuters.