Functional recovery after moderate/severe traumatic brain injury: a role for cognitive reserve?
OBJECTIVE
To evaluate the hypothesis that educational attainment, a marker of cognitive reserve, is a predictor of disability-free recovery (DFR) after moderate to severe traumatic brain injury (TBI).


METHODS
Retrospective study of the TBI Model Systems Database, a prospective multicenter cohort funded by the National Institute on Disability and Rehabilitation Research. Patients were included if they were admitted for rehabilitation after moderate to severe TBI, were aged 23 years or older, and had at least 1 year of follow-up. The main outcome measure was DFR 1 year postinjury, defined as a Disability Rating Scale score of zero.


RESULTS
Of 769 patients included, 214 (27.8%) achieved DFR at 1 year. In total, 185 patients (24.1%) had <12 years of education, while 390 (50.7%) and 194 patients (25.2%) had 12 to 15 years and ≥16 years of education, respectively. DFR was achieved by 18 patients (9.7%) with <12 years, 120 (30.8%) with 12 to 15 years, and 76 (39.2%) with ≥16 years of education (p < 0.001). In a logistic regression model controlling for age, sex, and injury- and rehabilitation-specific factors, duration of education of ≥12 years was independently associated with DFR (odds ratio 4.74, 95% confidence interval 2.70-8.32 for 12-15 years; odds ratio 7.24, 95% confidence interval 3.96-13.23 for ≥16 years).


CONCLUSIONS
Educational attainment was a robust independent predictor of 1-year DFR even when adjusting for other prognostic factors. A dose-response relationship was noted, with longer educational exposure associated with increased odds of DFR. This suggests that cognitive reserve could be a factor driving neural adaptation during recovery from TBI.
From the Center for Surgical Trials and Outcomes Research, Department of Surgery (E.B.S., D.T.E., X.H., S. Selvarajah, H.L.H.), Division of Neurosciences Critical Care, Departments of Anesthesiology and Critical Care Medicine (R.G.K., R.D.S.), and Departments of Neurology (R.D.S.) and Neurosurgery (R.D.S.), Johns Hopkins School of Medicine, Baltimore, MD; Tulane Center for Aging (S. Sur), Tulane University School of Medicine, New Orleans, LA; Department of Radiology (V.R., J.D., R.D.S.), Johns Hopkins University, Baltimore, MD; and Centre for Mental Health (V.R.), Department of Medicine, Imperial College London, UK.
Eric B
EB
Schneider
Sandeepa
S
Sur
Vanessa
V
Raymont
Josh
J
Duckworth
Robert G
RG
Kowalski
David T
DT
Efron
Xuan
X
Hui
Shalini
S
Selvarajah
Hali L
HL
Hambridge
Robert D
RD
Stevens
D000368:Aged; D001930:Brain Injuries / Q000150:complications* / Q000534:rehabilitation; D003072:Cognition Disorders / Q000209:etiology*; D015331:Cohort Studies; D004185:Disability Evaluation; D004522:Educational Status; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D020127:Recovery of Function / Q000502:physiology*