ost traumatic brain injuries (TBIs) occur as a result of falls, car accidents and assaults, while players of contact sports, such as football and boxing, tend to sustain what is known as repetitive head impacts (RHI). TBI can also be caused by stroke, brain tumours, alcohol or other poisoning, hypoxia/anoxia (reduced or complete starvation of oxygen to the brain), and neurodegenerative neurological disorders.
So, while some brain injuries are more easily preventable than others, it is becoming increasingly clear that no matter how they are sustained, any injury to brain tissue can initiate long-term neurodegeneration and the risk of Alzheimer’s disease in later life. In 2013 the American National Football League even made a multimillion-pound settlement to more than 4,500 of their retired football players who had gone on to develop dementia (including Alzheimer’s) and depression.
Epidemiological studies that analyse the incidence of people developing Alzheimer’s disease after TBIs have in the past shown conflicting results. While not firmly established, there is now a growing body of scientific evidence that suggests head injuries, particularly RHIs can increase the risk of Alzheimer’s.
These studies have in general also indicated an association between TBI and the development of Alzheimer’s earlier than for those without any type of brain injury. One hypothesis is that the amyloid-beta plaques, one of the key hallmarks of Alzheimer’s pathology, form rapidly from the accumulation of the precursor protein for amyloid, known as the amyloid precursor protein (APP), in the damaged nerve fibres (axons) of nerve cells (neurons).
The following scientific papers explore the link between head injury and the risk of Alzheimer’s and other dementias:
- Ramos-Cejudo, J, et.al. (2018). Traumatic Brain Injury and Alzheimer’s Disease: The Cerebrovascular Link. EBioMedicine, 28, 21–30
- Li, Y, et.al. (2017). Head Injury as a Risk Factor for Dementia and Alzheimer’s Disease: A Systematic Review and Meta-Analysis of 32 Observational Studies. PLoS ONE, 12(1), e0169650
- Kenney, K, et.al. (2018). Dementia After Moderate-Severe Traumatic Brain Injury: Coexistence of Multiple Proteinopathies. Journal of Neuropathology and Experimental Neurology, 77(1), 50–63.
Prevention is definitely better than cure, particularly when it comes to any type of brain injury. The following are just a few examples of the ways you can prevent yourself from either TBI or RHI – finally some new risk reduction factors that are not explicitly lifestyle-based, I hear you say!
Make sure there are no trip hazards and there is good lighting around the home
Ensure important items are within easy reach so you don’t need to use step ladders and overreach
Always look ahead for any obstacles when you are out walking, just as you would when driving
Improve strength, balance and coordination with regular exercise to prevent falls
Always wear a helmet when riding a bike, motorcycle or a horse; when skating, skateboarding, snowboarding or skiing; and when playing contact sports such as football and boxing
And the number one way to prevent brain injury in a car accident? Make sure you and your passengers wear a seatbelt at all times.