title: Systematic review of the risk of dementia and chronic cognitive impairment after mild traumatic brain injury: results of the International Collaboration on Mild Traumatic Brain Injury Prognosis.
abstract: OBJECTIVE
  To synthesize the best available evidence regarding the risk of dementia and chronic cognitive impairment (CCI) after mild traumatic brain injury (MTBI).
  
  
  METHODS
  MEDLINE and other databases were searched (2001-2012) using a previously published search strategy and predefined criteria. Peer-reviewed reports in 6 languages were considered.
  
  
  METHODS
  Systematic reviews, meta-analyses, randomized controlled trials, cohort studies, and case-control studies, with a minimum of 30 MTBI cases in subjects of any age, assessing the risk of dementia or CCI after MTBI were selected.
  
  
  METHODS
  Eligible studies were critically appraised using a modification of the Scottish Intercollegiate Guidelines Network criteria. Two reviewers independently reviewed each study and extracted data from accepted articles (ie, with a low risk of bias) into evidence tables.
  
  
  RESULTS
  Evidence from accepted studies was synthesized qualitatively according to modified Scottish Intercollegiate Guidelines Network criteria, and prognostic information was prioritized as exploratory or confirmatory according to design. Of 77,914 records screened, 299 articles were eligible and reviewed. Methodological quality was acceptable for 101 (34%) articles, of which 1 article considered dementia and 7 articles considered CCI. The study examining the risk of dementia after MTBI did not find an association. One randomized controlled trial found that being informed about possible cognitive dysfunction after MTBI was associated with worse cognitive performance on standard tests. Children with MTBI and intracranial pathology ("complicated" MTBI) performed worse than did children without intracranial pathology. Children showed higher rates of cognitive symptoms a year after MTBI than did a control group.
  
  
  CONCLUSIONS
  There is a lack of evidence of an increased risk of dementia after MTBI. In children, objective evidence of CCI exists only for complicated MTBI. More definitive studies are needed to inform clinical decisions, assessment of prognosis, and public health policy.
authors.affiliation: University Department of Rehabilitation Medicine, Danderyd Hospital, Karolinska Institute, Stockholm, Sweden. Electronic address: alison.godbolt@ki.se.
authors.forename: Alison K
authors.initials: AK
authors.lastname: Godbolt
authors.affiliation: Division of Health Care and Outcomes Research, Toronto Western Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada; Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Carol
authors.initials: C
authors.lastname: Cancelliere
authors.affiliation: Division of Health Care and Outcomes Research, Toronto Western Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada; Division of Epidemiology, Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Cesar A
authors.initials: CA
authors.lastname: Hincapié
authors.affiliation: Department of Medicine, University of Toronto, Toronto, Ontario, Canada; Morton and Gloria Shulman Movement Disorders Centre, and the Edmond J. Safra Program in Parkinson's Research, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Connie
authors.initials: C
authors.lastname: Marras
authors.affiliation: Division of Epidemiology, Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada; Faculty of Health, Institute of Sport Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark.
authors.forename: Eleanor
authors.initials: E
authors.lastname: Boyle
authors.affiliation: Division of Epidemiology, Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada; Department of Health Sciences, Lakehead University, Thunder Bay, Ontario, Canada; Institute for Work and Health, Toronto, Ontario, Canada; Division of Human Sciences, Northern Ontario School of Medicine, Lakehead University, Thunder Bay, Ontario, Canada.
authors.forename: Vicki L
authors.initials: VL
authors.lastname: Kristman
authors.affiliation: National Center for Injury Prevention and Control, Centers for Disease Control and Prevention, Atlanta, GA.
authors.forename: Victor G
authors.initials: VG
authors.lastname: Coronado
authors.affiliation: Division of Health Care and Outcomes Research, Toronto Western Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada; Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Ontario, Canada; Division of Epidemiology, Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada; Faculty of Health, Institute of Sport Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark.
authors.forename: J David
authors.initials: JD
authors.lastname: Cassidy
mesh_terms: D001930:Brain Injuries / Q000150:complications / Q000175:diagnosis* / Q000628:therapy*; D060825:Cognitive Dysfunction / Q000209:etiology*; D003704:Dementia / Q000209:etiology*; D006801:Humans; D011379:Prognosis; D015599:Trauma Severity Indices
keywords: Cognition disorders; Craniocerebral trauma; Dementia; Outcome assessment; Prognosis; Rehabilitation