Low Incidence of CTE Found Among US Service Members Interview with:
Daniel Perl MD
Uniformed Services University of the Health Sciences
Professor of Pathology at USUHS and
Director of the CNRM’s Brain Tissue Repository
Uniformed Services University of the Health Sciences
Bethesda, Maryland  What is the background for this study? 

Response: Chronic traumatic encephalopathy (CTE) is a brain disorder that is predominantly seen in individuals who have suffered from repeated impact head trauma, such as occurs in former boxers or American football players.  CTE has very specific alterations in the brain and can only be diagnosed at autopsy.  Some have claimed that, in addition to former contact sport participants, individuals who served in the military and were repeatedly exposed to blast (explosions) are also at increased risk for developing CTE.  However, this claim has been based on a rather small number of anecdotal cases.  The DoD/USU Brain Tissue Repository is the only facility in the world that is exclusively dedicated to the collection and study of donated brain specimens derived from deceased active duty and retired service members.  We used the resources of this facility to examine 225 consecutively collected brain specimens for the presence of CTE.  This would to provide a view of how common CTE was in this setting and, when diagnosed, was the disease correlated with prior blast exposure, participation in contact sports and other forms of head trauma, and with certain forms of symptomatology such as development of PTSD, alcohol/substance abuse, death by suicide, etc.  What are the main findings?

Response: Of the 225 brains examined from military personnel, we found only 10 specimens which showed neuropathologic features diagnostic of CTE and of those identified cases, involvement of the brain by the disease tended to be rather minimal (e.g. half showed only one CTE-related lesion, despite extensive sampling).  All of the identified cases diagnosed with CTE had a history of participation in contact sports in addition to their having served in the military.  It would appear from our data that CTE is uncommon among military personnel and that exposure to repeated blast does not represent a substantial risk factor for the development of the disease. What should readers take away from your report?

Response: That chronic traumatic encephalopathy (CTE) is rather rare in US service members and when seen, it tends to be rather mild in terms of brain involvement and it is typically associated with prior participation in contact sports, especially football.  If we could find only 10 cases of CTE among 225 brain specimens examined, in a young active mostly male population, this suggests that this disease is not as common as is frequently claimed in the general civilian active male population.  While we could not claim that the cohort studied reflects the makeup of the general civilian population (or the military, for that matter), if in this group of mostly male active and relatively young individuals who are those who sign up to serve in the military, we could only document a diagnosis of the disease in 4.4% (and remember, half of the cases had very minimal involvement of the brain – only one CTE-related lesion could be documented in the brain samples), then we believe this says something about overall risks in people who never played contact sports professionally.  Additionally, our data indicate that CTE was not a significant contributor to prominent sequelae commonly seen in service members, such as PTSD, alcohol/drug abuse or suicide. What recommendations do you have for future research as a result of this work?

Response: We need to continue the collection and study of additional donated brain specimens that are derived from both symptomatic and non-symptomatic service members in order to better understand the effects of a military career on brain health (our DoD/USU Brain Tissue Repository’s overall mission). Is there anything else you would like to add?

Response: Yes, most of the individuals studied in this reports who were most heavily exposed to combat (especially blast-exposed) died at a relatively young age.  Studies of CTE in contact sport athletes show that there is a considerable period of latency between when they are exposed to head trauma during their athletic careers and when they become symptomatic with the disease.  This period of latency can be several decades in duration.  There are many examples of former NFL players who had successful business careers, success in sports casting, etc. for extended period of time before finally becoming symptomatic with CTE later in life.  We can only report our data on the cases we have available to examine.  In coming years we may identify additional cases of CTE in former service members who served in the 20 year period of the War on Terror (2001 to 2021) and who were so extensively exposed to blast.  Only time and further studies will tell.

We have no financial disclosures to report. 


Chronic Traumatic Encephalopathy in the Brains of Military Personnel

David S. Priemer, M.D., Diego Iacono, M.D., Ph.D., C. Harker Rhodes, M.D., Ph.D.,
Cara H. Olsen, Dr.P.H., and Daniel P. Perl, M.D.
June 9, 2022 N Engl J Med 2022; 386:2169-2177
DOI: 10.1056/NEJMoa2203199

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Last Updated on June 9, 2022 by Marie Benz MD FAAD