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Abstract
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BACKGROUND: Traumatic brain injury (TBI) has been related to dementia, but the impact of life-course TBI on dementia remains unclear. We aimed to examine the association between lifespan TBI and dementia, and to explore whether genetic and early-life environmental factors contribute to this association.
METHOD: Within the Swedish Twin Registry,35,312 dementia-free twins (mean age 62.78 years) were followed for up to 18 years.Life-course TBI was assessed based on information from the SwedishNational Patient Registry (NPR) and participants were divided into five groups according to age at TBI occurrence (≤39, 40-49, 50-59, 60-69, and ≥70 years). Dementia and cardiovascular disease (CVD, including heart disease and stroke) diagnoses were ascertained based on medical records in the NPR and the SwedishCause of Death Register. Data were analyzed using generalized estimating equation (GEE) and conditional logistic regression.
RESULT: In multi-adjustedGEE model, the odds ratios (ORs, 95% confidence intervals [CIs]) of dementia were 1.29 (1.05-1.60) for TBI at any age, 1.01 (0.54-1.89)for TBI at ≤39 years, 1.11 (0.65-1.88) for TBI at 40-49 years, 1.66 (1.13-2.45) for TBI at 50-59 years, 1.84 (1.24-2.74) for TBI at 60-69 years, and 0.86 (0.55-1.34) for TBI at ≥70 years, respectively. In the conditional logistic regression, the OR (95% CI) of dementia for TBI at any age was 1.59 (1.04-2.45). The difference in ORs from the two models was not statistically significant (P =0.40). In joint exposure analysis, the multi-adjusted OR (95% CI) of dementia was 1.46 (1.04-2.04) for participants with TBI but no CVD and 2.64 (1.63-4.29) for those with both TBI and CVD (reference: absence of both TBI and CVD). There was significant additive (attributable proportion0.48, 95% CI 0.17-0.78) and multiplicative interactions (OR1.98, 95% CI 1.09-3.60) betweenTBI at 50-69 years and CVD on dementia.
CONCLUSION: TBI, especially occurring at age 50-69 years, is associated with increased risk of dementia, and the risk becomes greater in people with CVD.Genetic and early-life environmental factors may not account for the TBI-dementia association.
Language: en |