The Bidirectional Association of TBI and Dementia/MCI among older US Veterans

Abstract

AbstractBackgroundPrior studies have reported a link between traumatic brain injury (TBI) and risk of adverse neuropsychiatric outcomes including dementia. However it is unclear how prevalent these conditions are prior to TBI and if they are predisposing factors in addition to sequalae.MethodsWe studied older (age >55 years) US veterans who were followed for care at Veterans Affairs Medical Centers across the nation from 2000 to 2019. We first identified all veterans with an incident TBI diagnoses defined as no prior TBI diagnosis, having been seen in an emergency department (ED), having a brain imaging scan (primarily CT) within one day of ED visit and with a subsequent new TBI diagnosis in the electronic medical record (EMR). We then determined 2‐year age‐adjusted prevalence rates (rate per 1000 person‐years and 95% confidence interval or CI) for dementia and mild cognitive impairment (MCI) prior to and post incident TBI. We also compared prior TBI prevalence to prevalence among 1:3 matched (on age and index date) veterans without TBI.ResultsThere were 13,709 primarily male veterans with incident TBI with mean age of 77.7 sd 9.1 years, 81% were non‐Hispanic White. Compared to the 41,127 veterans without TBI (mean age = 77.9, sd 9.1), veterans prior to having an incident TBI had almost a six‐fold greater pre‐TBI age‐adjusted prevalence of dementia (104.9; 95% CI 100.8‐109.0 vs 18.6; 95% CI 17.6‐19.7, p<0.001) and MCI (48.0; 95% CI 45.2‐50.7 vs 8.1; 95% CI 7.4‐8.8, p<0.001). After the incident TBI diagnosis, the age‐adjusted prevalence rates were even higher: dementia (193.5; 95% CI 187.7‐199.2) and MCI (59.3; 95% CI 56.0‐62.6).ConclusionsAmong older US veterans, there is a bidirectional association with dementia/ MCI and TBI with very high prevalence prior to TBI (compared to those without TBI) and even greater prevalence after TBI. These findings highlight the importance of prevention strategies for both pre‐ and post‐TBI cognitive impairment.