Stenberg J, Håberg AK, Follestad T, Olsen A, Iverson GL, Terry DP, Karlsen RH, Saksvik SB, Karaliute M, Ek JAN, Skandsen T, Vik A. Arch. Phys. Med. Rehabil. 2019; ePub(ePub): ePub.
Affiliation
Department of Neuromedicine and Movement Science, Norwegian University of Science and Technology (NTNU), Trondheim, Norway; Department of Neurosurgery, St Olavs Hospital, Trondheim University Hospital, Trondheim, Norway.
OBJECTIVE: To investigate whether cognitive reserve moderates differences in cognitive functioning between patients with mild traumatic brain injury (MTBI) and controls, and to examine whether patients with postconcussional syndrome have lower cognitive functioning than patients without, at 2 weeks and 3 months after injury.
DESIGN: Trondheim MTBI follow-up study is a longitudinal controlled cohort study with cognitive assessments 2 weeks and 3 months after injury. SETTING: Recruitment at a level 1 trauma center and at a general practitioner-run, out-patient clinic. PARTICIPANTS: Patients with MTBI (n=160) according to the World Health Organization criteria, trauma controls (n=71), community controls (n=79). MAIN MEASURES: A cognitive composite score was used as outcome measure. The Vocabulary subtest was used as a proxy of cognitive reserve. Postconcussional syndrome diagnosis was assessed at 3 months with the British Columbia Postconcussion Symptom Inventory.
RESULTS: Linear mixed models demonstrated that the effect of vocabulary scores on the cognitive composite scores was larger in patients with MTBI than in community controls at 2 weeks and at 3 months after injury (P=0.001). Thus, group differences in the cognitive composite score varied as a function of vocabulary scores, with the biggest differences seen among participants with lower vocabulary scores. There were no significant differences in the cognitive composite score between patients with (n=29) and without (n=131) postconcussional syndrome at 2 weeks or 3 months after injury.
CONCLUSION: Cognitive reserve, but not postconcussional syndrome, was associated with cognitive outcome after MTBI. This supports the cognitive reserve hypothesis in the MTBI context and suggests that persons with low cognitive reserve are more vulnerable to reduced cognitive functioning if they sustain an MTBI.