Hindawi Publishing Corporation Rehabilitation Research and Practice Volume 2012, Article ID 371970, 5 pages doi:10.1155/2012/371970 Review Article Mild Traumatic Brain Injury: Lessons Learned from Clinical, Sports, and Combat Concussions Judy C. Kelly, Eﬂand H. Amerson, and Jeffrey T. Barth Department of Psychiatry & Neurobehavioral Sciences, University of Virginia, Charlottesville, VA 22908, USA Correspondence should be addressed to Judy C. Kelly, jck6c@virginia.edu Received 21 December 2011; Accepted 1 February 2012 Academic Editor: Brian D. Greenwald Copyright © 2012 Judy C. Kelly et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Over the past forty years, a tremendous amount of information has been gained on the mechanisms and consequences of mild traumatic brain injuries. Using sports as a laboratory to study this phenomenon, a natural recovery curve emerged, along with standards for managing concussions and returning athletes back to play. Although advances have been made in this area, inves- tigation into recovery and return to play continues. With the increase in combat-related traumatic brain injuries in the military setting, lessons learned from sports concussion research are being applied by the Department of Defense to the assessment of blast concussions and return to duty decision making. Concussion management and treatment for military personnel can be com- plicated by additional combat related stressors not present in the civilian environment. Cognitive behavioral therapy is one of the interventions that has been successful in treating symptoms of postconcussion syndrome. While we are beginning to have an understanding of the impact of multiple concussions and subconcussive blows in the sports world, much is still unknown about the impact of multiple blast injuries. 1. Introduction As early as 1962, Symonds made the observation that any concussion, no matter how mild, may result in permanent neurologic impairment [1, 2]. Almost a decade later, re- searchers in New Zealand ﬁrst documented delayed return to work and complex processing speed deﬁcits related to “minor head injury” [3]. By the early 1980’s, neuroscientists at the University of Virginia were ﬁnding that patients who had sustained a concussion were slow to return to work and were continuing to experience deﬁcits in attention, memory, new problem solving, mental ﬂexibility, and cognitive pro- cessing speed three months postinjuries [4, 5]. Around this same time, animal studies were revealing neuropathological/histological changes in the brain stems of primates when subjected to acceleration deceleration, rota- tional injuries, or mild traumatic brain injuries (mTBIs) [2, 6]. These acceleration or torque forces were expressed as “shear-strain”, or stretching and tearing of axonal ﬁbers. Concurrent neurochemical cascades occur during any sever- ity of traumatic brain injury (TBI). These reactions to trau- ma typically involve the rapid transfer of potassium and sodium to the extracellular space, the inﬂux of calcium, and the release of oxygen free radicals, which can result in cell death (apoptosis). Returning to a homeostatic state requires energy (glucose) and time, which in the case of mild con- cussion is often 5 to 10 days. To better understand the neurocognitive sequel of this concussion phenomenon in humans, a new method of study was initiated at the University of Virginia: the Sports as a Laboratory Assessment Model (SLAM) [2]. This research model involved the use of contact sports as a controlled lab- oratory to collect brief baseline neurocognitive test data that would later be compared to repeat postconcussion test data. In the ﬁrst study of its kind, more than 2300 football players at 10 universities were assessed before the football season with brief neurocognitive tests [7]. When a concussion oc- curred in these players, the same preseason battery was ad- ministered 24 hours, 5 days, and 10 days postinjury. Scores on these measures were not only compared to the preseason performance of the individual athlete, but also to a matched control (redshirt) group (a student athlete who delays eligibility to play, typically during their freshman year of college) at the same time intervals. On neurocognitive tests,