Increased Risk of Dementia and its Subtypes following Various Forms of Acquired Brain Injury: a Meta-analysis and Systematic Review.

In recent years, acquired brain injuries (ABIs) have been implicated in the development and pathogenesis of dementia; however, existing data is conflicting and often lacks precise classifications or comprehensive analyses. This review sought to synthesize available evidence to assess the association between four major ABI types-traumatic brain injury (TBI), cerebral atherosclerosis (AS), intracranial hemorrhage, and ischemic stroke-and risk of subsequent all-cause dementia (ACD) and dementia subtypes, including Alzheimer's disease (AD), vascular dementia (VaD), frontotemporal lobar degeneration (FTLD), and dementia with Lewy bodies (DLB). A comprehensive literature review was conducted across public databases, assessing studies published until February 2025, and garnering 107 studies that met inclusion criteria. Meta-analysis of pooled odds ratios (ORs) and 95% confidence intervals (CIs) indicated that TBI was associated with increased ACD, AD, VaD, and FTLD (OR: 1.79, CI: 1.66-1.92, OR: 1.60, CI: 1.44-1.77, OR: 2.03, CI: 1.79-2.30, and OR: 3.99, CI: 2.20-7.20, respectively); cerebral AS was linked to increased odds of ACD, VaD, and FTLD (OR: 1.29, CI: 1.14-1.45, OR: 2.77, CI: 1.72-4.44, and OR: 1.16, CI: 1.07-1.26, respectively); and both intracranial hemorrhage and ischemic stroke conferred increased risks for ACD, AD, and VaD (OR: 2.40, CI: 2.27-2.55, OR: 1.28, CI: 1.03-1.59, and OR: 5.75, CI: 4.73-6.99, as well as OR: 1.24, CI: 1.18-1.31, OR: 1.89, CI: 1.79-2.00, and OR: 2.01, CI: 1.80-2.25, respectively). This meta-analysis indicates a significant relationship between various ABIs and subsequent dementia with variation in subtype-specific associations, underscoring the importance of ABI prevention and post-injury monitoring to mitigate dementia risk.