Is Dementia Risk Increased Among Veterans After Mild TBI Without Loss of Consciousness?

Bottom Line: Traumatic brain injury (TBI), even mild TBI without a loss of consciousness, was associated with increased risk for dementia in a study of more than 350,000 U.S. veterans.

Why The Research Is Interesting: TBI is common among veterans and civilians. In the military, TBI can be caused by shock waves from blasts, as well as blunt force, and it may not result in a loss of consciousness. Moderate and severe TBIs have previously been associated in some studies with increased dementia risk but an association between dementia and mild TBI, especially without an accompanying loss of consciousness, has been unclear.

Who and When: 178,779 patients diagnosed with TBI in the Veterans Health Administration health care system from 2001 to 2014 and an equal number of veterans without TBI for comparison

What (Study Measures): Dementia diagnosis

How (Study Design): This was an observational study. Researchers were not intervening for purposes of the study and cannot control for all the natural differences that could explain the study results.

Authors: Deborah Barnes, Ph.D., M.P.H., and Kristine Yaffe, M.D., of the Veterans Health Care System, San Francisco, and the University of California, San Francisco, and coauthors

Results:

Even after accounting for medical and psychiatric coexisting conditions, the risk for dementia was increased for mild TBI without a loss of consciousness (LOC), mild TBI with LOC, mild TBI when it was unknown if there was LOC, and for moderate to severe TBI.

Study Limitations: The study used medical record databases based on clinician diagnoses, which may not reflect consensus definitions for TBI or dementia.

Study Conclusions: 

Related Material:  The editorial, “Risk of Dementia Outcomes Associated With Traumatic Brain Injury During Military Service,” by Kimbra Kenney, M.D., of the Uniformed Services University of the Health Services, Bethesda, Maryland, and Ramon Diaz-Arrastia, M.D., Ph.D., of the University of Pennsylvania Perelman School of Medicine, Philadelphia, also is available on the For The Media website.

To read the full study, please visit the For The Media website.

(doi:10.1001/jamaneurol.2018.0347)