title: Reduced amygdalar gray matter volume in familial pediatric bipolar disorder.
abstract: OBJECTIVE
  Subcortical limbic structures have been proposed to be involved in the pathophysiology of adult and pediatric bipolar disorder (BD). We sought to study morphometric characteristics of these structures in pediatric subjects with familial BD compared with healthy controls.
  
  
  METHODS
  Twenty children and adolescents with BD I (mean age = 14.6 years, four females) and 20 healthy age, gender, and IQ-matched controls underwent high-resolution magnetic resonance imaging at 3 T. Patients were mostly euthymic and most were taking medications. Amygdala, hippocampus, thalamus, and caudate volumes were determined by manual tracings from researchers blinded to diagnosis. Analyses of covariance were performed, with total brain volume, age, and gender as covariates.
  
  
  RESULTS
  No differences were found in the volumes of hippocampus, caudate, and thalamus between subjects with BD and controls. Subjects with BD had smaller volumes in the left and right amygdala, driven by reductions in gray matter volume. Exploratory analyses revealed that subjects with BD with past lithium or valproate exposure tended to have greater amygdalar gray matter volume than subjects with BD without such exposure.
  
  
  CONCLUSIONS
  Children and adolescents with early-onset BD may have reduced amygdalar volumes, consistent with other studies in this population. Prolonged medication exposure to lithium or valproate may account for findings in adults with BD of increased amygdalar volume relative to controls.
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA 94305-5540, USA. kchang88@stanford.edu
authors.forename: Kiki
authors.initials: K
authors.lastname: Chang
authors.forename: Asya
authors.initials: A
authors.lastname: Karchemskiy
authors.forename: Naama
authors.initials: N
authors.lastname: Barnea-Goraly
authors.forename: Amy
authors.initials: A
authors.lastname: Garrett
authors.forename: Diana Iorgova
authors.initials: DI
authors.lastname: Simeonova
authors.forename: Allan
authors.initials: A
authors.lastname: Reiss
mesh_terms: D000293:Adolescent; D000679:Amygdala / Q000473:pathology*; D001714:Bipolar Disorder / Q000175:diagnosis / Q000235:genetics* / Q000473:pathology; D002421:Caudate Nucleus / Q000473:pathology; D002648:Child; D015331:Cohort Studies; D004292:Dominance, Cerebral / Q000502:physiology; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics; D006624:Hippocampus / Q000473:pathology; D006801:Humans; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D010555:Personality Inventory; D012016:Reference Values; D013788:Thalamus / Q000473:pathology