J Head Trauma Rehabil. 2017 May 17. doi: 10.1097/HTR.0000000000000325. [Epub
ahead of print]
Steward KA(1), Kennedy R, Novack TA, Crowe M, Marson DC, Triebel KL.
OBJECTIVE: To examine whether cognitive reserve (CR) attenuates the initial
impact of traumatic brain injury (TBI) on cognitive performance (neural reserve)
and results in faster cognitive recovery rates in the first year postinjury
(neural compensation), and whether the advantage of CR differs on the basis of
the severity of TBI.
SETTING: Inpatient/outpatient clinics at an academic medical center.
PARTICIPANTS: Adults with mild TBI (mTBI; n = 28), complicated mild TBI (cmTBI; n
= 24), and moderate to severe TBI (msevTBI; n = 57), and demographically matched
controls (n = 66).
DESIGN: Retrospective, longitudinal cohort assessed at 1, 6, and 12 months
MAIN MEASURES: Outcomes were 3 cognitive domains: processing speed/executive
function, verbal fluency, and memory. Premorbid IQ, estimated with the Wechsler
Test of Adult Reading, served as CR proxy.
RESULTS: Higher premorbid IQ was associated with better performance on cognitive
domains at 1 month postinjury, and the effect of IQ was similarly beneficial for
all groups. Cognitive recovery rate was moderated only by TBI severity; those
with more severe TBI had faster recovery in the first year.
CONCLUSION: Results support only the neural reserve theory of CR within a TBI
population and indicate that CR is neuroprotective, regardless of the degree of
TBI. Higher premorbid CR does not allow for more rapid adaptation and recovery