The Biological Basis of Chronic Traumatic Encephalopathy following Blast Injury: A Literature Review.

The United States Department of Defense Blast Injury Research Program Coordinating Office organized the 2015 International State-of-the-Science meeting to explore links between blast-related head injury and the development of chronic traumatic encephalopathy (CTE). Before the meeting, the planning committee examined articles published between 2005 and October 2015 and prepared this literature review, which summarized broadly CTE research and addressed questions about the pathophysiological basis of CTE and its relationship to blast- and nonblast-related head injury. It served to inform participants objectively and help focus meeting discussion on identifying knowledge gaps and priority research areas. CTE is described generally as a progressive neurodegenerative disorder affecting persons exposed to head injury. Affected individuals have been participants primarily in contact sports and military personnel, some of whom were exposed to blast. The symptomatology of CTE overlaps with Alzheimer's disease and includes neurological and cognitive deficits, psychiatric and behavioral problems, and dementia. There are no validated diagnostic criteria, and neuropathological evidence of CTE has come exclusively from autopsy examination of subjects with histories of exposure to head injury. The perivascular accumulation of hyperphosphorylated tau (p-tau) at the depths of cortical sulci is thought to be unique to CTE and has been proposed as a diagnostic requirement, although the contribution of p-tau and other reported pathologies to the development of clinical symptoms of CTE are unknown. The literature on CTE is limited and is focused predominantly on head injuries unrelated to blast exposure (e.g., football players and boxers). In addition, comparative analyses of clinical case reports has been challenging because of small case numbers, selection biases, methodological differences, and lack of matched controls, particularly for blast-exposed individuals. Consequently, the existing literature is not sufficient to determine whether the development of CTE is associated with head injury frequency (e.g., single vs. multiple exposures) or head injury type (e.g., impact, nonimpact, blast-related). Moreover, the incidence and prevalence of CTE in at-risk populations is unknown. Future research priorities should include identifying additional risk factors, pursuing population-based longitudinal studies, and developing the ability to detect and diagnose CTE in living persons using validated criteria.

Mortality Surveillance for Infectious Diseases in the U.S. Department of Defense (1998-2013).

INTRODUCTION: The Mortality Surveillance Division (MSD) of the U.S. Armed Forces Medical Examiner System was established in 1998 to improve surveillance for all military deaths although emphasizing deaths from infectious diseases. Establishment of the MSD was part of the 1997 Department of Defense initiative to improve surveillance and response for emerging infectious diseases. Before 1998, mortality surveillance was limited to compiling information from death certificates, a system that provided limited useful information and lacked the timeliness needed to take meaningful action to address emerging infectious disease threats. MATERIALS AND METHODS: The MSD was tasked to quickly identify all infectious disease deaths and the infecting agents. The system developed by the MSD staff identified deaths in near real-time and immediately notified military Public Health authorities of situations that warranted an investigation. Autopsy, medical, and investigative reports were collected. Testing specimens for agent identification was encouraged. The data and information collected were archived in the MSD-developed Medical Mortality Registry (MMR), a database that included all active duty Service Member deaths and contained manner and cause of death with medical, demographic, circumstantial, and diagnostic information. The MMR was the only comprehensive, autopsy-based source for mortality information on active duty military deaths. RESULTS: During 1998-2013, 217 (1.3%) infectious disease deaths were identified among 16,192 noncombat deaths. Of the 217 deaths, 29.5% were classified as respiratory, 18.0% cardiac, 15.2% blood borne, 12.9% nervous system, and 12.4% sepsis. A pathogen was identified for 64.5%. Agents of military interest identified included Neisseria meningitidis, influenza viruses, adenoviruses, and malaria. Neisseria meningitidis was identified in 10 fatal cases; grouping of the agent was done for eight cases. Four were group B, two were C, and two were Y. All eight had been immunized with a quadrivalent meningococcal vaccine. The most commonly detected respiratory agent was influenza virus (nine deaths), three of which were the 2009 pandemic H1N1 influenza virus. Adenoviruses were identified as the infectious agents in a total of nine deaths. Two deaths resulted from Plasmodium falciparum malaria infections acquired in Africa during military deployments. An important but unexplained finding was that Black Service Members made up only16.3% of all military personnel but accounted for 28.6% of all infectious disease deaths. CONCLUSION: The time lag between death and notification of the MSD at the start of this surveillance program was 24 to 48 hours. The lag at the end of the reported surveillance period was 8 to 24 hours. The MSD surveillance system identified an agent in 140 of 217 (64.5%) uniformed deaths. In a similar program by the Centers for Disease Control and Prevention, in 122 cases with specimens, an agent could be identified in 34 (28%). MMR data and information provided strong support for re-establishing the military recruit adenovirus vaccination program, which ceased in 1999 and was finally re-established in 2011. MMR data and information also assisted in monitoring the military meningococcal vaccine program, helped to describe the virulence of circulating influenza viruses, and identified areas where deadly malaria infections were not being prevented.

Sudden death in young adults: an autopsy-based series of a population undergoing active surveillance.

OBJECTIVES: The purpose of this study was to define the incidence and characterization of cardiovascular cause of sudden death in the young. BACKGROUND: The epidemiology of sudden cardiac death (SCD) in young adults is based on small studies and uncontrolled observations. Identifying causes of sudden death in this population is important for guiding approaches to prevention. METHODS: We performed a retrospective cohort study using demographic and autopsy data from the Department of Defense Cardiovascular Death Registry over a 10-year period comprising 15.2 million person-years of active surveillance. RESULTS: We reviewed all nontraumatic sudden deaths in persons 18 years of age and over. We identified 902 subjects in whom the adjudicated cause of death was of potential cardiac etiology, with a mean age of 38 ± 11 years. The mortality rate for SCD per 100,000 person-years for the study period was 6.7 for males and 1.4 for females (p < 0.0001). Sudden death was attributed to a cardiac condition in 715 (79.3%) and was unexplained in 187 (20.7%). The incidence of sudden unexplained death (SUD) was 1.2 per 100,000 person-years for persons <35 years of age, and 2.0 per 100,000 person-years for those ≥ 35 years of age (p < 0.001). The incidence of fatal atherosclerotic coronary artery disease was 0.7 per 100,000 person-years for those <35 years of age, and 13.7 per 100,000 person-years for those ≥ 35 years of age (p < 0.001). CONCLUSIONS: Prevention of sudden death in the young adult should focus on evaluation for causes known to be associated with SUD (e.g., primary arrhythmia) among persons <35 years of age, with an emphasis on atherosclerotic coronary disease in those ≥ 35 years of age.