title: Is traumatic brain injury a risk factor for schizophrenia? A meta-analysis of case-controlled population-based studies.
abstract: Traumatic brain injury (TBI) is known to lead to a range of adverse psychiatric sequelae but the question of whether TBI is a risk factor for psychosis and, in particular, schizophrenia remains unclear. Studies examining this issue have yielded conflicting results. We carried out a systematic review of the literature on TBI and psychosis in order to identify all population-based controlled studies which provide estimates of risk for schizophrenia following TBI. Odds ratios (ORs) were combined using random effects meta-analysis. Our literature search yielded 172 studies which were considered to be potentially relevant. From these, we identified 9 studies that could provide estimates of risk in the form of ORs. The pooled analysis revealed a significant association between TBI and schizophrenia (OR = 1.65; 95% CI = 1.17-2.32), with significant heterogeneity between the studies. Estimates from the family studies (OR = 2.8: 95% CI =1.76-4.47) were higher than those from the cohort/nested case-control studies (OR = 1.42: 95% CI = 1.02-1.97) by a factor of almost 2. There did not appear to be a dose-response relationship between severity of head injury and subsequent risk of schizophrenia. This meta-analysis supports an increased risk of schizophrenia following TBI, with a larger effect in those with a genetic predisposition to psychosis. Further epidemiological and neuroscientific studies to elucidate the mechanisms underlying this association are warranted.
authors.affiliation: Department of Psychiatry, Royal College Of Surgeons in Ireland, Education and Research Centre, Dublin 9, Ireland.
authors.forename: Charlene
authors.initials: C
authors.lastname: Molloy
authors.forename: Ronan M
authors.initials: RM
authors.lastname: Conroy
authors.forename: David R
authors.initials: DR
authors.lastname: Cotter
authors.forename: Mary
authors.initials: M
authors.lastname: Cannon
mesh_terms: D001930:Brain Injuries / Q000150:complications* / Q000523:psychology*; D006801:Humans; D011618:Psychotic Disorders / Q000453:epidemiology / Q000209:etiology / Q000523:psychology; D012107:Research Design; D012307:Risk Factors; D012559:Schizophrenia / Q000453:epidemiology / Q000209:etiology*