Top military researchers say, and the evidence corroborates, that there are no good statistics on how many troops have suffered mild traumatic brain injuries and how many still have persistent symptoms. The Pentagon's official numbers show that 115,000 have received "mild" TBIs -- although senior military researchers say that is very likely far lower than the true toll. A study by Rand, the independent think tank, estimates that there have been roughly 400,000 TBIs, most of which are "mild."
Studies of civilians show that most people with mild TBIs get better spontaneously, within a few days or weeks, but 5 percent to 15 percent suffer symptoms that last months or years.
So, you do the math: All this suggests that between roughly 5,750 and 60,000 troops are still affected by mild TBIs. Those soldiers can no longer "think straight." Many read a paragraph and immediately forget it. Some struggle to comprehend instructions. Others may lose their way home, and even need to keep a list in their bedroom reminding them how to get dressed.