 The purpose of this study is to compare the sensitivity of the DANA Rapid exam with the MACE cognitive score. The primary hypothesis is that the DANA Rapid exam will be more sensitive for detecting impaired cognitive performance than the MACE cognitive score in the setting of a clinical diagnosis of concussion at the point of injury in the combat setting. A secondary purpose of this study is to examine a serial performance on the DANA Rapid exam in those subjects diagnosed with a concussion. The secondary hypothesis is that the DANA Rapid exam will show improvements in performance during the recovery period after concussion. 