Systematic Review on the Association of a Traumatic Brain Injury (TBI) and Development of Alzheimer's Disease (AD)

Abstract

<h3>Objective(s)</h3> The purpose of this systematic review was to examine the association of a traumatic brain injury and development of Alzheimers. <h3>Data Sources</h3> This review was conducted using the following databases: Taylor & Francis, Science Direct, Google Scholar, and ProQuest Central. Inclusion criteria consisted of peer-reviewed articles published in English between the years of 1999-2017. Keywords for the search included Alzheimer's Disease, dementia, traumatic brain injury, and TBI. A total number of 26 articles were reviewed, and 5 articles were retained. <h3>Study Selection</h3> Literature Review. <h3>Data Extraction</h3> Independent extraction by multiple observers. <h3>Data Synthesis</h3> Articles reviewed demonstrate consistency in the association between increased risk for AD and history of head trauma, specifically early onset when TBIs are experienced at an older age. Additionally, sustaining a TBI at an older age increases the risk of rapid progression and functional impairment following onset of AD. Overall, studies analyzed report TBI as a possible precipitating factor of AD. Research suggests the mechanisms involved in TBI and Apoe4 may be linked to AD pathology, specifically, Aβ plaques. Furthermore, these plaques are more prevalent at a younger age in cognitively intact individuals with Apoe4 genetic predispositions when compared to non-carriers. Of note, plaques identified in TBI individuals resemble those found in early stages of AD. <h3>Conclusions</h3> Research indicated that although a scarcity of research exists on factors that may influence AD progression, helpful information such as history of TBI and its recency may be useful tools. This may also assist in predicting prognosis and in identifying severity of disability. Risk factors include higher rates of functional decline in AD, specifically for individuals where TBI occurred relatively close to the onset of AD. Further research should be conducted to evaluate possible preclinical features of AD, such as the predisposition to falls resulting in head trauma, to identify potential alternative explanations and possible pathological overlap between AD and TBI. <h3>Author(s) Disclosures</h3> N/A.