Army chief Ray Odierno and NFL Commissioner Roger Goodell have signed a formal letter of agreement.

Odierno said both the military and football breed a culture of mental and physical toughness and putting one's team first. He said that can make it hard for soldiers and players to spot mental health problems.

The two leaders said they would work to change that culture. In addition, the NFL wants to adapt Army technology.

The Army uses helmet sensors to measure the impact to a soldier's head after an explosion or other incident that can cause TBI. Defense officials said there are about 2,000 documented cases of brain injury across the military, most of them in the Army.

This story is part of Federal News Radio's daily DoD Report. For more defense news, click here.