The role of traumatic brain injury (TBI) as a risk factor for or cause of neurodegenerative disease is currently an important subject of research and the topic of some controversy in recent years. The discussion of has been ongoing for almost 100 years, starting with the concept of dementia pugilistica or being “Punch Drunk” published in the Journal of the American Medical Association in 1928 by Dr. Harrison Martland. More recently, numerous studies have linked various levels of TBI to an increased risk of developing Alzheimer’s disease, as well as causing an earlier onset for Alzheimer’s disease (Bilbul & Schipper, 2011; Jellinger, 2004; Johnson, Stewart, & Smith, 2010; Lye & Shores, 2000). Researchers Li, Risacher, McAllister and Saykin (2016), found that a history of TBI may accelerate the age of onset of cognitive impairment by two or more years leading to an earlier age of onset for mild cognitive impairment and Alzheimer’s disease.
ABSTRACT: Traumatic brain injury and age at onset of cognitive impairment in older adults (2016)
There is a deficiency of knowledge regarding how traumatic brain injury (TBI) is associated with age at onset (AAO) of cognitive impairment in older adults. Participants with a TBI history were identified from the Alzheimer's disease neuroimaging initiative (ADNI 1/GO/2) medical history database. Using an analysis of covariance (ANCOVA) model, the AAO was compared between those with and without TBI, and potential confounding factors were controlled. The AAO was also compared between those with mild TBI (mTBI) and moderate or severe TBI (sTBI). Lastly, the effects of mTBI were analyzed on the AAO of participants with clinical diagnoses of either mild cognitive impairment (MCI) or Alzheimer's disease (AD). The AAO for a TBI group was 68.2 ± 1.1 years [95 % confidence interval (CI) 66.2-70.3, n = 62], which was significantly earlier than the AAO for the non-TBI group of 70.9 ± 0.2 years (95 % CI 70.5-71.4, n = 1197) (p = 0.013). Participants with mTBI history showed an AAO of 68.5 ± 1.1 years (n = 56), which was significantly earlier than the AAO for the non-TBI group (p = 0.032). Participants with both MCI and mTBI showed an AAO of 66.5 ± 1.3 years (95 % CI 63.9-69.1, n = 45), compared to 70.6 ± 0.3 years for the non-TBI MCI group (95 % CI 70.1-71.1, n = 935) (p = 0.016). As a conclusion, a history of TBI may accelerate the AAO of cognitive impairment by two or more years. These results were consistent with reports of TBI as a significant risk factor for cognitive decline in older adults, and TBI is associated with an earlier AAO found in patients with MCI or AD.
Li, W., Risacher, S. L., McAllister, T. W., & Saykin, A. J. (2016). Traumatic brain injury and age at onset of cognitive impairment in older adults. Journal of Neurology, 1-6.
A video discussion of the relationship between TBI and Alzheimer’s disease by Dr. Michael Weiner, MD, of the University of California, San Francisco.
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