Mild traumatic brain injury, alternately termed concussion, is defined as a change in mental status resulting from trauma or rotational forces (e.g., whiplash) to the brain, with or without loss of consciousness (Quality Standards Subcommittee, 1997) . Each year in the United States 1.5 million people suffer traumatic brain injuries (CDC, 2003) , 20% of which are sports-related (CDC, 1997) . The incidence and prevalence of concussion ranges from 3 to 24% of sports-related injuries in high school and college athletics (Gerberich et al. , 1983; Guskiewicz et al. , 2000; Powell and Barber-Foss, 1999) . Military service has occupational risks similar to those of contact sports, and concussion surveillance models recently have been implemented in military operational and training settings (Salazar et al. , 2000) . Early results of such work, based on concussion surveillance at Fort Bragg, indicate that 23% of paratroopers had sustained a concussion since the time of Army enlistment (Ivins et al. , 2003) .
Concussion poses a difficult diagnostic situation due to the typical absence of neuroimaging or other objective medical abnormalities, and due to the subtle and often nonspecific nature of the symptoms. Though acute symptoms often resolve over a period of days (Bleiberg et al. , In Press) , a longer-lasting post concussion syndrome can ensue (Ingebrigtsen et al. , 1998; Mittenberg and Strauman, 2000) , with symptoms including headache, fatigue, attention and concentration difficulties, memory impairment, depressed or anxious mood, irritability, and sleep disturbance (Kelly, 2000) . Post-concussion syndrome is significant due to the presence of cognitive impairments that include slowed reaction time and slowed information processing speed. Such impairments jeopardize safe return to the at-risk sport or occupation, in essence leaving the individual vulnerable to re-injury. Such re-injury is not just a hypothetical possibility, but has been well documented in numerous studies as discussed below.
Accurate return-to-play or return-to-duty decisions are crucial for three reasons: 1) the individual may be at increased risk for a second concussive injury; 2) the individual may be at risk for potentially fatal injury if the concussions are contiguous; and 3) and recurring concussions may lead to chronic, long-term cognitive impairment or emotional dysfunction. Individuals who have suffered one concussion are more likely to experience a second concussion in the same athletic season, and the post-concussion symptoms are likely to be more severe and long-lasting as injuries accumulate (Collins et al. , 2002; Guskiewicz et al. , 2000) . There are documented cases of second impact syndrome, in which fatal injuries result from two or more quite mild but close-occurring concussive injuries (Cantu, 1998; Kelly and Rosenberg, 1998) . Finally, while the prevalence and nature of chronic, long-term cognitive and emotional impairment secondary to concussion remains controversial, there is general agreement that the accumulation of recurring, particularly closely-spaced, concussions is harmful.
Neuropsychological assessment, particularly computerized neuropsychological assessment, has documented clinical utility for use in concussion surveillance and management protocols, particularly return-to-play decision making (Bleiberg et al. , 1998b; Collie et al. , 2001; Erlanger et al. , 2003) . In conjunction with assessment of physical and emotional symptoms, neuropsychological assessment has been used to document the course of recovery from cognitive symptoms of concussion (Bleiberg et al. , In Press; Erlanger et al. , 2003) . There is significant evidence that cognitive symptoms extend beyond physical symptoms and can remain for a week or more post-injury (Bleiberg et al. , In Press; Erlanger et al. , 2003; Lovell et al. , 2003) . The major cognitive symptoms of slowed processing speed and impaired attentional abilities may leave an athlete or military personnel more vulnerable to a second, possibly more severe concussion.
Computerized neuropsychological assessment offers many benefits: ease of group administration, brief administration time, and ease of widespread public health application. However, the computerized neuropsychological assessment procedures currently available -- with the exception of ANAM -- are distributed by for-profit companies, are expensive, and often involve software licensing fees in excess of $1000 combined with additional fees for retesting injured children. Given that the CDC has declared concussion from sports an "epidemic" among America 's children, we do not think that financial capability should be the determining factor in whether a child does or does not receive services. ANAM has and continues to be sponsored by the Army Medical Research and Material Command, Department of Defense. ANAM and ASMB are distributed free of charge, and thus are suitable for addressing concussion at a public health level.
The current test battery originated from research using ANAM to study traumatic brain injury. The success of these early studies led to a series of sports concussion studies in civilian and military settings, resulting in a version of ANAM containing subtests with known sensitivity and specificity to concussion, referred to as the ANAM Sports Medicine Battery (ASMB). Though much published empirical research has been generated from these efforts, ASMB continues to lack an integrated approach to psychometric development, particularly a system for combining the efforts of multiple research projects across diverse institutions. There also is lack of an established system for communicating user recommendations and experiences to the ANAM software development team. Thus, while thousands of athletes have been assessed using ASMB, there has been no systematic attempt to combine and integrate these data, nor has there been a forum for users to share experiences with one another and facilitate development of collaborative, multicenter protocols.
The present proposal seeks to establish a mechanism for collaboration among current ASMB users. The key features of this mechanism are: regular meetings with published proceedings; sharing of data sets to permit more powerful analyses; cross –validation studies (e.g. clinical decision-making rules derived from one institution's sample can be tested using another institution's sample); development of norms with large sample-sizes; and, preparation of multi-institution proposals. Moreover, since concussion management is a concern for military personnel as well as for civilian athletes, the present "working group" will include military personnel.
One of the most important outcomes of creating a systematic and coherent aggregation of ANAM data across multiple institutions is these data can serve as an empirical foundation for using ANAM as a clinical instrument. With rare exception, ANAM to this point has been used as a research instrument. The ASMB Working Group is composed of scientists who have used ANAM in sports concussion research conducted by world-class universities and hospitals. The data from the studies, as well as the combined expertise of these scientists/clinicians, will be utilized as a "peer-review" to assess ANAM's current suitability for clinical practice and to identify current and future needs. The "proceedings" of this group will contain many elements of an ANAM user's manual and interpretative guide, to maximize appropriate use of ANAM and to prevent and discourage inappropriate or dangerous applications.