Can a Concussion Cause Alzheimer’s Disease?

Alzheimer’s disease is a progressive neurodegenerative disease that destroys a person’s memory and cognitive functions. The condition damages the brain cell connections, causing the cells to degenerate and die, thus destroying memory and other related mental functions. Confusion and memory loss are the main symptoms of this condition, and there is, as of yet, no cure for Alzheimer’s disease. There has been a lot of debate on what is the exact cause of Alzheimer’s disease, with new research suggesting that moderate to severe traumatic brain injury can increase the risk of Alzheimer’s in many people. Concussion resulting from brain trauma has been linked to brain changes in people who are at risk for Alzheimer’s. Read on to find out more about can a concussion cause Alzheimer’s disease.

Can a Concussion Cause Alzheimer’s Disease?

Alzheimer’s disease is a progressive neurodegenerative disorder that destroys brain cells and causes loss of memory and other critical mental functions.(1,2) Alzheimer’s disease is known to be the most common cause of dementia, in which a person experiences a gradual decline in their behavioral, thinking, and social skills.(3) The condition disrupts a person’s ability to live independently. The condition is believed to be caused by an abnormal build-up of certain toxic proteins in and around the brain cells.(4,5)

While the exact cause of Alzheimer’s disease is not known, but many researchers always suspected that moderate to severe brain injury was a known risk factor for conditions that affect the brain, such as Alzheimer’s disease. Now, a new study has linked concussion and an increased risk of genetic risk for Alzheimer’s.

Research from the Boston University School of Medicine (BUSM) reported that their study showed promise of detecting the impact of a concussion on neurodegeneration.(6) The study has been published in the journal Brain.

This research follows in the footsteps of several other studies that have linked mild to severe traumatic brain injury or concussion to dementia.(7)

Alzheimer’s disease attacks the brain cells and tends to worsen with time. As mentioned above, Alzheimer’s is the most common form of dementia, which is an umbrella term used for diseases that lead to a decline of a person’s mental faculties.(8,9) Over time, mental deterioration becomes severe enough to start interfering with day to day life.

Alzheimer’s disease is one of the leading causes of death worldwide and in the United States, which can neither be prevented nor cured.(10) It is estimated that over five million people in the US alone live with Alzheimer’s disease, and this number is only expected to grow exponentially in the coming years as the baby boomer generation starts entering the age of 65 and over.(11)

The study carried out by BUSM noted that moderate to severe traumatic brain injury had been established as being the strongest environmental risk factor for developing late-onset Alzheimer’s and other forms of dementia or neurodegenerative disorders. However, it is still unclear if the risk is the same for mild traumatic brain injury, which the research team wanted to find.(12)

Looking at the Research

The research team looked at 160 war veterans who were in the age group of 19 to 58 years and had served in Afghanistan and Iraq. Many of these veterans were diagnosed with mild traumatic brain injury and had post-traumatic stress disorder (PTSD).(13)

The participants were all given MRI scan from which the researchers took measurements of the thickness in the cortical brain regions. These regions are known to show deterioration in the early stages of Alzheimer’s disease. The measurements from the cortical brain regions were then compared with measurements taken from control regions.

At the same time, researchers also calculated the genetic risk score for Alzheimer’s for each participant. This was done by comparing results from the participants’ genotype tests with information on high-risk genes taken from a larger Alzheimer’s disease genome study.(14)

The results showed that concussion or a mild traumatic brain injury had a significant influence on the genetic risk for developing Alzheimer’s disease. This link has been established between the cortical thickness and the genetic risk for Alzheimer’s disease. Participants who had a high genetic risk and had suffered a concussion were found to have decreased cortical thickness in the regions of the brain that are identified as being susceptible to Alzheimer’s disease.(15)

At the same time, the researchers also found that the cortical thinning in the Alzheimer’s vulnerable regions in the brain had a role to play in the reduced memory performance.

As a result, the researchers recommend that there is a need for people to keep a record of even mild head injuries because if there is a genetic risk for Alzheimer’s already present, then these mild head injuries may go on to become long-term health problems, including brain diseases.

Conclusion

A new research study has found that experiencing a concussion, even a mild one, can increase the risk of developing Alzheimer’s disease if you already have a genetic risk to the disease. It was previously known that a moderate to severe traumatic brain injury increases your risk of developing dementia, even up to 30 years after the injury.

However, this new study has also shown that even a mild traumatic injury to the brain can increase the risk of developing Alzheimer’s at an older age.

The results of this study have highlighted the importance of properly documenting any concussion events, no matter how minor you feel they are. Also, make a note of their symptoms, even if you simply thought that it took you a bit longer to ‘shake it off.’ The researchers hope to spread awareness about the dangers of having a concussion and how any type of injury to the brain can prove to be dangerous in the future. The study also shows promise in helping doctors detect any potential brain deterioration that a concussion might inflict in the early years itself. However, more research is still needed to look at the exact mechanisms that accelerate the deterioration of the brain after a concussion.

References:

  1. Alzheimer’s Disease and Dementia. 2020. What Is Alzheimer’s?. [online] Available at: <https://www.alz.org/alzheimers-dementia/what-is-alzheimers> [Accessed 16 June 2020].
  2. Cdc.gov. 2020. What Is Alzheimer’s Disease? | CDC. [online] Available at: <https://www.cdc.gov/aging/aginginfo/alzheimers.htm> [Accessed 15 June 2020].
  3. Alzheimer’s Association, 2016. 2016 Alzheimer’s disease facts and figures. Alzheimer’s & Dementia, 12(4), pp.459-509.
  4. LaFerla, F.M., Green, K.N. and Oddo, S., 2007. Intracellular amyloid-β in Alzheimer’s disease. Nature Reviews Neuroscience, 8(7), pp.499-509.
  5. Selkoe, D.J., 1991. The molecular pathology of Alzheimer’s disease. Neuron, 6(4), pp.487-498.
  6. Hayes, J.P., Logue, M.W., Sadeh, N., Spielberg, J.M., Verfaellie, M., Hayes, S.M., Reagan, A., Salat, D.H., Wolf, E.J., McGlinchey, R.E. and Milberg, W.P., 2017. Mild traumatic brain injury is associated with reduced cortical thickness in those at risk for Alzheimer’s disease. Brain, 140(3), pp.813-825.
  7. Nordström, A. and Nordström, P., 2018. Traumatic brain injury and the risk of dementia diagnosis: A nationwide cohort study. PLoS medicine, 15(1).
  8. Ferri, C.P., Prince, M., Brayne, C., Brodaty, H., Fratiglioni, L., Ganguli, M., Hall, K., Hasegawa, K., Hendrie, H., Huang, Y. and Jorm, A., 2005. Global prevalence of dementia: a Delphi consensus study. The lancet, 366(9503), pp.2112-2117.
  9. Prince, M., Bryce, R., Albanese, E., Wimo, A., Ribeiro, W. and Ferri, C.P., 2013. The global prevalence of dementia: a systematic review and metaanalysis. Alzheimer’s & dementia, 9(1), pp.63-75.
  10. Evans, D.A., 1990. Estimated prevalence of Alzheimer’s disease in the United States. The Milbank Quarterly, pp.267-289.
  11. Evans, D.A., Funkenstein, H.H., Albert, M.S., Scherr, P.A., Cook, N.R., Chown, M.J., Hebert, L.E., Hennekens, C.H. and Taylor, J.O., 1989. Prevalence of Alzheimer’s disease in a community population of older persons: higher than previously reported. Jama, 262(18), pp.2551-2556.
  12. Røe, C., Sveen, U., Alvsåker, K. and Bautz-Holter, E., 2009. Post-concussion symptoms after mild traumatic brain injury: influence of demographic factors and injury severity in a 1-year cohort study. Disability and rehabilitation, 31(15), pp.1235-1243.
  13. Hoge, C.W., McGurk, D., Thomas, J.L., Cox, A.L., Engel, C.C. and Castro, C.A., 2008. Mild traumatic brain injury in US soldiers returning from Iraq. New England journal of medicine, 358(5), pp.453-463.
  14. Harold, D., Abraham, R., Hollingworth, P., Sims, R., Gerrish, A., Hamshere, M.L., Pahwa, J.S., Moskvina, V., Dowzell, K., Williams, A. and Jones, N., 2009. Genome-wide association study identifies variants at CLU and PICALM associated with Alzheimer’s disease. Nature genetics, 41(10), p.1088.
  15. Querbes, O., Aubry, F., Pariente, J., Lotterie, J.A., Démonet, J.F., Duret, V., Puel, M., Berry, I., Fort, J.C., Celsis, P. and Alzheimer’s Disease Neuroimaging Initiative, 2009. Early diagnosis of Alzheimer’s disease using cortical thickness: impact of cognitive reserve. Brain, 132(8), pp.2036-2047.

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