Overview

Mild TBI is known as a risk factor for Alzheimer’s, however, there haven’t been previous studies discussing to what extent one would lead to the other quantitatively. A research team at the University of Southern California hoped to explore this important issue and the results revealed that patterns of neurodegeneration in TBI and Alzheimer’s resemble greatly. Furthermore, they developed tools to predict the severity of brain atrophy after TBI based on post-traumatic cognitive impairment. 

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Head injury and Dementia 

Meta-analysis have concluded that head injury serves as a risk factor for Dementia and AD (Alzheimer’s Disease). Epedimological studies also showed that biomarkers of mTBI patients shared similarity with ones of Alzheimer’s. The risk factor can even be applied to other neurodegenerative dieases like Parkinson’s. 

 

Methods 

31 mTBI patients participated in this study, along with 66 Alzheimer’s patients and 81 healthy members. The research team measured their brain changes using MRI scans and developed machine learning tools to explore the correlation. 

 

Cortical thinning 

Cortical thickness is neocortex thickness. It is the outermost layer of our brain, usually called “mamalian brain”, that is in charge of higher level intelligence, emotions and memory. Study have discovered positive relationship between cortical thickness and IQ scores. One of the result is that patients with mTBI showed reduced cortical thickness in MRI scans compared to the control group. Other study have explored the correlation between cortical thinning and cognitive impairment in AD and Dementia. 

 

Gray Matter 

Gray matter is the area that mainly composed of cell bodies of neurons, where decision-making and memory processing occurs. Study demonstrated similar pattern of gray matter reduction in both mTBI and Alzheimer’s patients while gray matter loss has been one of the characteristic signs of Alzheimer’s Disease.  

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White Matter 

White matter is the area where neurons branched out and connected with others. Patterns of neurodegeneration in fronix, corpus callosum and corona radiata, which are associated with memory, information exchange between hemispheres and movement of limbs. Previous studies have established white matter atrophy as a pathogenesis of Alzheimer’s Disease. 

 

Implications

Based on the results, assessments of cognitive impairment after mild TBI can predict AD-like neurodegenderation, which is correlated with risk of AD afterwards. The author, Andrei Irimia, talked about the medical implication of this study: “the results may help health professionals to identify TBI victims who are at greater risk for Alzheimer's disease.” 

 

Reference 

Amlien, I., & Fjell, A. (2014). Diffusion tensor imaging of white matter degeneration in Alzheimer’s disease and mild cognitive impairment. Neuroscience, 276, 206-215. doi:10.1016/j.neuroscience.2014.02.017

Brain changes following traumatic brain injury share similarities with Alzheimer's disease. (2021, April 26). Retrieved from https://www.sciencedaily.com/releases/2021/04/210426140732.htm

Câmara, D. (2015). Nervous System. Bio-inspired Networking, 45-80. doi:10.1016/b978-1-78548-021-8.50003-x

Du, A., Schuff, N., Kramer, J. H., Rosen, H. J., Gorno-Tempini, M. L., Rankin, K., . . . Weiner, M. W. (2006). Different regional patterns of cortical thinning in Alzheimers disease and frontotemporal dementia. Brain, 130(4), 1159-1166. doi:10.1093/brain/awm016

Frisoni, G. B. (2002). Detection of grey matter loss in mild Alzheimers disease with voxel based morphometry. Journal of Neurology, Neurosurgery & Psychiatry, 73(6), 657-664. doi:10.1136/jnnp.73.6.657

Govindarajan, K. A., Department of Diagnostic and Interventional Imaging, Narayana, P. A., Hasan, K. M., Wilde, E. A., Department of Physical Medicine and Rehabilitation, . . . Robertson, C. S. (2016, October 15). Cortical Thickness in Mild Traumatic Brain Injury. Retrieved from https://www.liebertpub.com/doi/10.1089/neu.2015.4253

Li, Y., Li, Y., Li, X., Zhang, S., Zhao, J., Zhu, X., & Tian, G. (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). doi:10.1371/journal.pone.0169650

M.washington, P., Villapol, S., & Burns, M. P. (2019). Polypathology and Dementia After Brain Trauma: Does Brain Injury Trigger Distinct Neurodegenerative Diseases, or Should They Be Classified Together as Traumatic Encephalopathy? Concussion and Traumatic Encephalopathy, 573-581. doi:10.1017/9781139696432.015

Menary, K., Collins, P. F., Porter, J. N., Muetzel, R., Olson, E. A., Kumar, V., . . . Luciana, M. (2013). Associations between cortical thickness and general intelligence in children, adolescents and young adults. Intelligence, 41(5), 597-606. doi:10.1016/j.intell.2013.07.010

Rostowsky, K. A., & Irimia, A. (2021). Acute cognitive impairment after traumatic brain injury predicts the occurrence of brain atrophy patterns similar to those observed in Alzheimer’s disease. GeroScience. doi:10.1007/s11357-021-00355-9

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