Veterans’ Dementia Risk Over 2x Higher with History of TBI

by Bianca Garilli, ND, USMC Veteran

Traumatic brain injury (TBI) has been shown to be a major cause of death and disability in the US, contributing to approximately 30% of all injury-related deaths.¹ TBIs can be caused by myriad of events including motor vehicle crashes, falls, and sports-related injuries.^1-2 In children and teens, 70% of concussions are related to sports related injuries, while in the elderly falls are the most common cause of concussions.^2-3

Previous research has indicated an association between moderate and severe TBI and increased risk or earlier onset of Alzheimer’s disease and dementia.⁴ However, few studies have looked into the link between mild TBI (also referred to as a “concussion”) events and increased risk of dementia.⁴

This research question is particularly important in the case of active duty military personnel and military veterans, where recent statistics have found that, “17% of Iraq and Afghanistan troops reported experiencing a mild TBI during deployment and, of these, 59% reported more than one mild TBI.”⁴ TBIs in this population are commonly a result of blast injuries from improvised explosive devices (IEDs), suicide bombers, land mines, mortar rounds, and rocket-propelled grenades, but can also occur while in garrison and during field training exercises.⁵

A publication in JAMA Neurology reported findings from a study that examined the association between TBI severity, loss of consciousness (LOC) from the TBI event, and dementia diagnosis in veterans.⁴ 

In this retrospective cohort study, 178,779 veterans from the Veterans Health Administration (VHA) health care system with a diagnosed TBI between October 1, 2001 and September 30, 2014 and 178,779 patients from a propensity-matched comparison veteran group without a TBI diagnosis were compared. Analyses explored the severity of the TBI they had experienced, whether the TBI was accompanied by LOC, and whether the veteran was subsequently diagnosed with dementia (individuals diagnosed with prion disease and alcohol- or drug-induced dementia were excluded from the study).⁴ Study participants were followed for an average of 4.2 years until they were diagnosed with dementia, died, or completed their most recent clinical visit (whichever came first).⁴

Study participants had a mean age of 49.5 years at their index date, where index date was defined as the date of their most severe TBI or, if multiple TBI dates with similar severity existed, the index date was defined as the date of the first TBI.⁴ Other demographics: 9.3% female; 72.5% non-Hispanic white; 16% non-Hispanic black; 1.8% Hispanic; 9.7% unknown or Other races/ethnicities.

Diagnostic data from the 178,779 veterans diagnosed with TBI includes:⁴

• 9.9% with mild TBI without LOC
• 12.9% mild TBI with LOC
• 30.8% mild TBI with LOC status unknown
• 46.4% with moderate or severe TBI

Data analysis showed there were a total of 10,835 cases of incident dementia (6.1%) in veterans with TBI compared to 4698 (2.6%) cases in veterans without TBI.⁴

The adjusted hazard ratio for dementia diagnosis in TBI-diagnosed individuals when compared to those without TBI events:⁴

• 2.36-fold increased risk for mild TBI without LOC
• 2.51-fold increased risk for mild TBI with LOC
• 3.19-fold increased risk for mild TBI with LOC status unknown
• 3.77-fold increased risk for moderate to severe TBI

Additionally, it was found that cumulative incidence of dementia based on age at diagnosis increased progressively with TBI severity, and the average time from index date to dementia diagnosis was 3.6 years in individuals with TBI and 4.8 years in those without TBI.⁴

The findings of this study indicate that even mild TBI without LOC is associated with >2-fold increase in dementia diagnosis, whereas LOC during TBI and increased severity of TBI further intensifies this risk.⁴

Why is this Clinically Relevant?

• Even mild TBI, with or without LOC, increases risk of dementia >2-fold
• Practitioners working with the veteran population should screen for history of TBI or events associated with TBI occurrence
• TBI-positive veterans should partner with practitioners well-versed in brain health and neurological healing, including Functional Medicine, lifestyle, and integrative medicine programs and protocols designed to improve TBI outcomes and prevent or prolong time to dementia diagnosis
• TBI-preventive protocols should be reviewed often and improved for active duty military personnel

Link to article

Citations

1. Taylor CA, Bell JM, Breiding MJ, Xu L. Traumatic brain injury related emergency department visits, hospitalizations, and deaths — United States, 2007 and 2013. MMWR Surveill Summ. 2017;66(9):1–16.
2. Haarbauer-Krupa J, Arbogast K, Metzger K, et al. Variations in mechanisms of injury for children with concussions. J Pediatr. 2018;197:241-248.
3. CDC. TBI – the facts. https://www.cdc.gov/traumaticbraininjury/get_the_facts.html. Accessed November 7, 2018.
4. Barnes D, Byers A, Gardner R, Seal K, Boscardin J, Yaffe K. Association of mild traumatic brain injury with and without loss of consciousness with dementia in us military veterans. JAMA Neurology. 2018;75(9):1055-1061.
5. DVBIC. TBI and the military. http://dvbic.dcoe.mil/tbi-military. Accessed November 7, 2018.