Cognitive reserve and persistent post-concussion symptoms--A prospective mild traumatic brain injury (mTBI) cohort study.

PRIMARY OBJECTIVE: Having three or more persisting (i.e. > 3 months) post-concussion symptoms (PCS) affects a significant number of patients after a mild traumatic brain injury (mTBI). A common complaint is cognitive deficits. However, several meta-analyses have found no evidence of long-term cognitive impairment in mTBI patients. The study sought to answer two questions: first, is there a difference in cognitive performance between PCS and recovered mTBI patients? Second, is lower cognitive reserve a risk factor for developing PCS?

RESEARCH DESIGN: Prospective inception cohort study.

METHODS AND PROCEDURE: One hundred and twenty-two adult patients were recruited from emergency departments within 24 hours of an mTBI. Three months post-injury, participants completed the Rivermead Post Concussion Symptoms Questionnaire and a neuropsychological assessment. A healthy control group (n = 35) were recruited. The estimate of cognitive reserve was based upon sub-test Information from Wechsler Adult Intelligence Scale and international classifications of educational level and occupational skill level.

MAIN OUTCOME AND RESULTS: mTBI patients showed reduced memory performance. Patients with lower cognitive reserve were 4.14-times more likely to suffer from PCS.

CONCLUSIONS: mTBI may be linked to subtle executive memory deficits. Lower cognitive reserve appears to be a risk factor for PCS and indicates individual vulnerabilities.