Brain Reserve Score on Acute Trauma Head CT is Correlated with Pre‐TBI MCI/Dementia and is an Independent Predictor of Post‐TBI Cognitive Outcome

Abstract

AbstractBackgroundPre‐injury brain reserve may contribute to the substantial heterogeneity observed in cognitive outcome after mild traumatic brain injury (mTBI), including risk for cognitive decline and dementia. However, no tools exist to quantify pre‐injury brain reserve in an acute trauma setting, thereby limiting research. We aimed to develop and validate a visually‐rated Brain Reserve Score (BRS) to quantify baseline brain reserve on head CTs obtained to rule out intracranial trauma in adults presenting acutely with mTBI.MethodsData are from the Transforming Research And Clinical Knowledge in Traumatic Brain Injury (TRACK‐TBI) and TRACK‐Geriatric TBI (TRACK‐GERI) studies, multi‐center prospective cohort studies of adults age 18+ presenting within 24 hours (TRACK‐TBI) or adults age 65y+ presenting within 72 hours (TRACK‐GERI) of TBI who received head CT and multi‐domain clinical follow‐up for one year. BRS was developed by adapting existing MRI visual rating scales of global cortical atrophy, hippocampal atrophy, and white matter change for use in trauma head CTs and then by refining the scoring guide to optimize rater reliability. To establish concurrent validity, we assessed correlation of BRS with pre‐injury cognitive status (measured in TRACK‐GERI using informant‐reported Clinical Dementia Rating interviews). To establish predictive validity, we assessed association of BRS with good versus poor 12‐month cognitive outcome in TRACK‐TBI using logistic regression adjusted for baseline demographics, medical/psychiatric comorbidities, injury characteristics, and trauma severity on CT.ResultsFinal BRS score ranged from 0‐10 (10 is highest burden of neuropathology); inter‐ and intra‐rater reliability were moderate‐substantial (weighted kappa 0.54‐0.80). Among N = 100 TRACK‐GERI participants BRS was significantly correlated with pre‐injury CDR (r = 0.37, p<0.01). Among N = 656 TRACK‐TBI participants, BRS of 6+ was independently associated with poor 12‐month cognitive outcome (fully adjusted odds ratio 4.35, 95% confidence interval 1.35‐13.99, p = 0.01).ConclusionBRS is a reliable visually rated score of brain reserve on acute trauma head CT that correlates with pre‐injury cognitive status and independently predicts poor cognitive outcome one year post‐mTBI. BRS may be a useful tool to facilitate inclusion of older adults in acute TBI research thereby advancing clinical care and research on mechanisms of accelerated post‐TBI cognitive decline and dementia.