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.
Inpatient/outpatient clinics at an academic medical center.
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).
Retrospective, longitudinal cohort assessed at 1, 6, and 12 months postinjury.
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.
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.
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 from injury.
Department of Psychology (Ms Steward and Dr Crowe), Department of Medicine (Dr Kennedy), Department of Physical Medicine and Rehabilitation (Dr Novack), and Department of Neurology (Drs Marson and Triebel), University of Alabama at Birmingham.
Corresponding Author: Kayla A. Steward, BS, Department of Psychology, University of Alabama at Birmingham, Campbell Hall 415, 1530 3rd Ave South, Birmingham, AL 35294 (firstname.lastname@example.org).
This work was supported by the National Institute on Child Health and Human Development (grant 1R01HD053074) (Dr Marson, PI). The authors thank the following contributors: Sandra Caldwell, MA (UAB Department of Physical Medicine and Rehabilitation, data collection); UAB Neuropsychology Laboratory Staff (data collection); Pat R. Pritchard, MD (UAB Department of Surgery, referring study participants); and Sarah Nafziger, MD (UAB Department of Emergency Medicine, referring study participants).
The authors declare no conflicts of interest.