Risk of dementia after hospitalization due to traumatic brain injury: a longitudinal, population-based study

ObjectiveTraumatic brain injury (TBI) is considered a potential modifiable dementia risk factor. We aimed to determine whether TBI actually increases the risk of dementia when adjusting for other relevant dementia risk factors. MethodsNational prospective longitudinal cohort study that included 32,385 participants aged 25-64 during 1992-2012. Of these, 288 suffered from a major TBI (diagnosis of traumatic intracranial hemorrhage and hospital length of stay (LOS) [≥]3 days) and 406 from a minor TBI (concussion diagnosis and hospital LOS [≤]1 day). Dementia was defined as any first hospital contact with a diagnosis of dementia; first use of an anti-dementia drug; and dementia as an underlying or contributing cause of death. Follow-up until the end of 2017 yielded a total of 1,010 incident dementia cases. ResultsAfter adjusting for age and sex, hospitalization due to major TBI (hazard ratio [HR] 1.51, 95% CI 1.03-2.22), but not minor TBI, increased the risk of dementia. After additional adjustment for educational status, smoking status, alcohol consumption, physical activity, and hypertension, the association between major TBI and dementia weakened (HR 1.30, 95% CI 0.86-1.97). The risk factors most strongly attenuating the association between major TBI and dementia were alcohol consumption and physical activity. ConclusionThere was an association between major TBI and incident dementia. The association was attenuated after adjusting for confounders, especially alcohol consumption and physical activity. Minor TBI was not associated with an increased risk of dementia.