Dementia Resulting From Traumatic Brain Injury: What Is the Pathology?

Archives of neurology (Impact Factor: 7.42). 07/2012; 69(10):1-7. DOI: 10.1001/archneurol.2011.3747
Source: PubMed


Traumatic brain injury (TBI) is among the earliest illnesses described in human history and remains a major source of morbidity and mortality in the modern era. It is estimated that 2% of the US population lives with long-term disabilities due to a prior TBI, and incidence and prevalence rates are even higher in developing countries. One of the most feared long-term consequences of TBIs is dementia, as multiple epidemiologic studies show that experiencing a TBI in early or midlife is associated with an increased risk of dementia in late life. The best data indicate that moderate and severe TBIs increase risk of dementia between 2- and 4-fold. It is less clear whether mild TBIs such as brief concussions result in increased dementia risk, in part because mild head injuries are often not well documented and retrospective studies have recall bias. However, it has been observed for many years that multiple mild TBIs as experienced by professional boxers are associated with a high risk of chronic traumatic encephalopathy (CTE), a type of dementia with distinctive clinical and pathologic features. The recent recognition that CTE is common in retired professional football and hockey players has rekindled interest in this condition, as has the recognition that military personnel also experience high rates of mild TBIs and may have a similar syndrome. It is presently unknown whether dementia in TBI survivors is pathophysiologically similar to Alzheimer disease, CTE, or some other entity. Such information is critical for developing preventive and treatment strategies for a common cause of acquired dementia. Herein, we will review the epidemiologic data linking TBI and dementia, existing clinical and pathologic data, and will identify areas where future research is needed.

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Available from: Sharon B Shively, Jan 08, 2015
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    • "Although a causative link has not been established, both the civilian and military literature on TBI suggest that a history of brain trauma may be associated with enduring changes in brain structures, especially in the cerebral white matter (Kinnunen et al., 2011; Mac Donald et al., 2011, 2014; Wada et al., 2012; Bazarian et al., 2013; Morey et al., 2013; Tremblay et al., 2014; Taber et al., 2015). It has been shown that moderate or severe TBI is associated with an increased risk for late life dementia (Shively et al., 2012; Gardner et al., 2014), and that a history of concussion is a risk factor for degenerative disease in later life (Bower et al., 2003; Fleminger et al., 2003; Chen et al., 2007), including dementia of the Alzheimer's type (French et al., 1985; Fleminger et al., 2003; Sivanandam and Thakur, 2012). Others have suggested that multiple concussions or even subconcussive events, such as those experienced in contact sports, may predispose some individuals to develop a unique pattern of pathology based on increased levels of tau deposition (Omalu et al., 2011; Stern et al., 2011; Goldstein et al., 2012; Small et al., 2013; McKee and Robinson, 2014). "
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