title: Cognitive reserve and persistent post-concussion symptoms--A prospective mild traumatic brain injury (mTBI) cohort study.
abstract: 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?
  
  
  METHODS
  Prospective inception cohort study.
  
  
  METHODS
  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.
  
  
  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.
authors.affiliation: a Department of Clinical Sciences , Karolinska Institute and Department of Rehabilitation Medicine Stockholm , Danderyd University Hospital , Stockholm , Sweden.
authors.forename: Christian
authors.initials: C
authors.lastname: Oldenburg
authors.affiliation: b Dizziness Center , Neuropsychiatry Section , Stockholm , Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Lundin
authors.affiliation: c Department of Neurobiology , Care Sciences, and Society, Centre for Family Medicine (CeFAM), Karolinska Institutet , Stockholm , Sweden.|d Department of Psychiatry , Tiohundra AB , Norrtälje , Sweden.
authors.forename: Gunnar
authors.initials: G
authors.lastname: Edman
authors.affiliation: a Department of Clinical Sciences , Karolinska Institute and Department of Rehabilitation Medicine Stockholm , Danderyd University Hospital , Stockholm , Sweden.
authors.forename: Catharina
authors.initials: C
authors.lastname: Nygren-de Boussard
authors.affiliation: a Department of Clinical Sciences , Karolinska Institute and Department of Rehabilitation Medicine Stockholm , Danderyd University Hospital , Stockholm , Sweden.
authors.forename: Aniko
authors.initials: A
authors.lastname: Bartfai
mesh_terms: D000328:Adult; D001924:Brain Concussion / Q000150:complications / Q000523:psychology*; D016022:Case-Control Studies; D058245:Cognitive Reserve; D015331:Cohort Studies; D056344:Executive Function / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008569:Memory Disorders; D009483:Neuropsychological Tests; D038223:Post-Concussion Syndrome / Q000523:psychology*; D011446:Prospective Studies
keywords: Brain concussion; cognitive impairment; mild head injury; post-concussion symptoms; post-concussion syndrome