Research Reports - Dementia resulting from traumatic brain injury: What is the pathology?
Arch Neurol. 2012 Jul 9:1-7
Shively S, Scher AI, Perl DP, Diaz-Arrastia R
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