Alzheimer disease (AD) is the most common form of dementia in older individuals and probably develops as a result of complex interactions among multiple factors, including age, genetics, environment, lifestyle and traumatic brain injury (TBI). 1-5 The evidence has shown that there appears to be a strong link between future risk of Alzheimer's and serious TBI, but how TBI increase future risk of AD is still unclear. 6-8 TBI caused by contact sports, work accident or military blasts may induce acute or potentially long-lasting neurological dysfunction, including chronic traumatic encephalopathy. 4-6,8,9 The clinical features of TBI vary depending on the mechanistic types and severity of head injury. These features generally consist of cognitive