title: Meta-analysis of magnetic resonance imaging studies of the corpus callosum in bipolar disorder.
abstract: OBJECTIVE
  The corpus callosum (CC) plays a pivotal role in inter-hemispheric transfer and integration of information and is a relatively understudied structure in bipolar disorder (BD). Magnetic resonance imaging (MRI) studies have reported callosal abnormalities in this condition but findings have been inconsistent. Structural changes affecting the CC may underlie functional abnormalities in BD and could contribute to, or explain the pathophysiology of, the condition.
  
  
  METHODS
  A systematic review was carried out to identify, appraise and summarize MRI studies which compared callosal areas in BD with an unrelated control group. The findings were then synthesized using random effects meta-analysis. Consideration was given to a number of variables to explain heterogeneity.
  
  
  RESULTS
  Five case-control studies were identified. Bipolar patients showed reduced callosal areas in comparison with healthy volunteers with no evidence of heterogeneity or publication bias.
  
  
  CONCLUSIONS
  Findings from this study indicate that callosal areas are reduced in BD and suggest that a failure to integrate information across the hemispheres may contribute to the pathophysiology of the disorder. Further research is necessary to clarify the underlying cellular changes leading to these morphometric differences.
authors.affiliation: Neuroscience and Psychiatry Unit, University of Manchester, Manchester, UK. danilo.arnone@manchester.ac.uk
authors.forename: D
authors.initials: D
authors.lastname: Arnone
authors.forename: A M
authors.initials: AM
authors.lastname: McIntosh
authors.forename: P
authors.initials: P
authors.lastname: Chandra
authors.forename: K P
authors.initials: KP
authors.lastname: Ebmeier
mesh_terms: D000293:Adolescent; D000328:Adult; D001284:Atrophy; D001714:Bipolar Disorder / Q000175:diagnosis* / Q000503:physiopathology; D016022:Case-Control Studies; D003337:Corpus Callosum / Q000473:pathology* / Q000503:physiopathology; D004292:Dominance, Cerebral / Q000502:physiology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D017594:Publication Bias; D055815:Young Adult