Traumatic Brain Injury & Dementia

Traumatic brain injury (TBI) has gained increasing attention over the past few decades, as researchers start to discover the lasting impact to the brain. Specifically, TBI research has sought to uncover what diseases and conditions might be connected to such injuries; whether they might result from falls, contact sports, or car accidents, and whether they can be linked to neurodegenerative disease like those that cause dementia, such as Alzheimer’s disease (AD). In a paper from Leeds University, Mavroudis and colleagues conducted a meta-analysis of six papers exploring this connection and found that with some exceptions, history of traumatic brain injury might place someone at higher risk for developing dementia.  

Between the six papers, the researchers investigated the association between TBI and risk of dementia. All papers that examined the relationship between TBI and risk of dementia in general found that there was a significant association. After pooling the data from these studies, they found that individuals with a history of TBI had a higher likelihood of developing dementia compared to those with no history of TBI. However, findings on the link between TBI and AD were mixed, suggesting that TBI may be more closely associated with other forms of dementia, rather than AD specifically. Additional analysis showed that severity of the injury experienced was reflected in the degree of risk of developing dementia, with more severe TBI putting someone at greater risk of developing dementia in the future.  

How can brain injury put someone at risk of developing dementia? We don’t really know yet, but there are several theories. Research indicates that it could be that injury causes a chronic inflammatory state, which, as AD research has shown, is linked to dementia (Johnson 2023). Or other studies have indicated that it could be that trauma to the brain accelerates the aging process and just brings on natural decline in memory and cognitive function a lot earlier (Brett 2022). Some researchers theorize that TBI can increase deposition of amyloid beta (associated with AD), but, as Mavroudis and colleagues found in their meta-analysis, the weaker relationship between TBI and AD may refute this theory (Van Itallie 2019).  

Understanding the relationship between TBI and dementia risk is important., Not only does it allow physicians to know which of their patients might benefit from frequent cognitive testing, but it can allow those who believe they have experienced TBI to talk to a healthcare provider early on, allowing early intervention and prevention of cognitive decline. Knowing which groups of people are at higher risk of TBI, like athletes or members of the military, can allow providers to keep an eye out for their most vulnerable patients and can allow members of those groups to be proactive about keeping in touch with the healthcare system and prioritizing their brain health. However, to better understand how TBI might pave the way for neurodegenerative disease, we need more data. With additional research, we can better understand how to identify those at high risk for dementia and design interventions to stop disease from progressing and memory from declining. In the meantime, the information we have helps us place importance on preventing TBI and minimizing the effects on brain health. 

The Alzheimer’s Association’s tips on preventing and recognizing TBI: 

https://www.alz.org/alzheimers-dementia/what-is-dementia/related_conditions/traumatic-brain-injury#:~:text=Protecting%20your%20head%20by%20wearing,and%20buckling%20your%20seat%20belt. 

Article of Interest: 

Mavroudis I, Kazis D, Petridis FE, Balmus IM, Papaliagkas V, Ciobica A. The Association Between Traumatic Brain Injury and the Risk of Cognitive Decline: An Umbrella Systematic Review and Meta-Analysis. Brain Sci. 2024;14(12):1188. Published 2024 Nov 26. doi:10.3390/brainsci14121188 

Other papers referenced and cited in the article of interest: 

Johnson, N.H.; de Rivero Vaccari, J.P.; Bramlett, H.M.; Keane, R.W.; Dietrich, W.D. Inflammasome activation in traumatic brain injury and Alzheimer’s disease. Transl. Res. 2023, 254, 1–12. 

Brett, B.L.; Gardner, R.C.; Godbout, J.; Dams-O’Connor, K.; Keene, C.D. Traumatic Brain Injury and Risk of Neurodegenerative Disorder. Biol. Psychiatry 2022, 91, 498–507. 

Van Itallie, T.B. Traumatic brain injury (TBI) in collision sports: Possible mechanisms of transformation into chronic traumatic encephalopathy (CTE). Metabolism 2019, 100S, 153943.