title: Abnormalities in left inferior frontal gyral thickness and parahippocampal gyral volume in young people at high genetic risk for bipolar disorder.
abstract: Fronto-limbic structural brain abnormalities have been reported in patients with bipolar disorder (BD), but findings in individuals at increased genetic risk of developing BD have been inconsistent. We conducted a study in adolescents and young adults (12-30 years) comparing measures of fronto-limbic cortical and subcortical brain structure between individuals at increased familial risk of BD (at risk; AR), subjects with BD and controls (CON). We separately examined cortical volume, thickness and surface area as these have distinct neurodevelopmental origins and thus may reflect differential effects of genetic risk.
  
  
  
  We compared fronto-limbic measures of grey and white matter volume, cortical thickness and surface area in 72 unaffected-risk individuals with at least one first-degree relative with bipolar disorder (AR), 38 BD subjects and 72 participants with no family history of mental illness (CON).
  
  
  
  The AR group had significantly reduced cortical thickness in the left pars orbitalis of the inferior frontal gyrus (IFG) compared with the CON group, and significantly increased left parahippocampal gyral volume compared with those with BD.
  
  
  
  The finding of reduced cortical thickness of the left pars orbitalis in AR subjects is consistent with other evidence supporting the IFG as a key region associated with genetic liability for BD. The greater volume of the left parahippocampal gyrus in those at high risk is in line with some prior reports of regional increases in grey matter volume in at-risk subjects. Assessing multiple complementary morphometric measures may assist in the better understanding of abnormal developmental processes in BD.
authors.affiliation: School of Psychiatry, University of New South Wales,Sydney,Australia.
authors.forename: G
authors.initials: G
authors.lastname: Roberts
authors.affiliation: School of Psychiatry, University of New South Wales,Sydney,Australia.
authors.forename: R
authors.initials: R
authors.lastname: Lenroot
authors.affiliation: School of Psychiatry, University of New South Wales,Sydney,Australia.
authors.forename: A
authors.initials: A
authors.lastname: Frankland
authors.affiliation: Neuroscience Research Australia,Sydney,Australia.
authors.forename: P K
authors.initials: PK
authors.lastname: Yeung
authors.affiliation: School of Psychiatry, University of New South Wales,Sydney,Australia.
authors.forename: N
authors.initials: N
authors.lastname: Gale
authors.affiliation: School of Psychiatry, University of New South Wales,Sydney,Australia.
authors.forename: A
authors.initials: A
authors.lastname: Wright
authors.affiliation: School of Psychiatry, University of New South Wales,Sydney,Australia.
authors.forename: P
authors.initials: P
authors.lastname: Lau
authors.affiliation: School of Psychiatry, University of New South Wales,Sydney,Australia.
authors.forename: F
authors.initials: F
authors.lastname: Levy
authors.affiliation: School of Psychiatry, University of New South Wales,Sydney,Australia.
authors.forename: W
authors.initials: W
authors.lastname: Wen
authors.affiliation: School of Psychiatry, University of New South Wales,Sydney,Australia.
authors.forename: P B
authors.initials: PB
authors.lastname: Mitchell
mesh_terms: D000293:Adolescent; D000328:Adult; D001714:Bipolar Disorder / Q000000981:diagnostic imaging / Q000235:genetics / Q000473:pathology*; D002648:Child; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D020534:Parahippocampal Gyrus / Q000000981:diagnostic imaging / Q000473:pathology*; D017397:Prefrontal Cortex / Q000000981:diagnostic imaging / Q000473:pathology*; D012306:Risk; D055815:Young Adult
keywords: Bipolar disorder; cortical surface area; genetic risk; gyral volume; inferior frontal gyrus