title: Amygdala and hippocampal volumes in adolescents and adults with bipolar disorder.
abstract: BACKGROUND
  The purported functions of medial temporal lobe structures suggest their involvement in the pathophysiology of bipolar disorder (BD). Previous reports of abnormalities in the volume of the amygdala and hippocampus in patients with BD have been inconsistent in their findings and limited to adult samples. Appreciation of whether volumetric abnormalities are early features of BD or whether the abnormalities represent neurodegenerative changes associated with illness duration is limited by the paucity of data in juvenile samples.
  
  
  OBJECTIVE
  To investigate amygdala and hippocampal volume in adults and adolescents with BD.
  
  
  METHODS
  Subjects included 36 individuals (14 adolescents and 22 adults) in outpatient treatment for BD type I at a university hospital or Veterans Affairs medical center or in the surrounding community, and 56 healthy comparison subjects (23 adolescents and 33 adults).
  
  
  METHODS
  Amygdala and hippocampal volumes were defined and measured on high-resolution anatomic magnetic resonance imaging scans. We used a mixed-model, repeated-measures statistical analysis to compare amygdala and hippocampal volumes across groups while covarying for total brain volume, age, and sex. Potential effects of illness features were explored, including rapid cycling, medication, alcohol or other substance dependence, duration, and mood state.
  
  
  RESULTS
  For both the amygdala and hippocampal regions, we found an overall significant volume reduction in the BD compared with the control group (P<.0001). Amygdala volume reductions (15.6%) were highly significant (P<.0001). We observed a nonsignificant trend (P =.054) toward reductions in hippocampal volumes of lesser magnitude (5.3%). Effects of illness features were not detected.
  
  
  CONCLUSIONS
  These results suggest that BD is associated with decreased volumes of medial temporal lobe structures, with greater effect sizes in the amygdala than in the hippocampus. These abnormalities are likely manifested early in the course of illness, as they affected adolescent and adult subjects similarly in this sample.
authors.affiliation: Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut, USA. hilary.blumberg@yale.edu
authors.forename: Hilary P
authors.initials: HP
authors.lastname: Blumberg
authors.forename: Joan
authors.initials: J
authors.lastname: Kaufman
authors.forename: Andres
authors.initials: A
authors.lastname: Martin
authors.forename: Ronald
authors.initials: R
authors.lastname: Whiteman
authors.forename: Jane Hongyuan
authors.initials: JH
authors.lastname: Zhang
authors.forename: John C
authors.initials: JC
authors.lastname: Gore
authors.forename: Dennis S
authors.initials: DS
authors.lastname: Charney
authors.forename: John H
authors.initials: JH
authors.lastname: Krystal
authors.forename: Bradley S
authors.initials: BS
authors.lastname: Peterson
mesh_terms: D000293:Adolescent; D000328:Adult; D000679:Amygdala / Q000473:pathology*; D001284:Atrophy / Q000473:pathology; D001714:Bipolar Disorder / Q000175:diagnosis*; D001921:Brain / Q000473:pathology; D002648:Child; D005260:Female; D006624:Hippocampus / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008432:Mathematical Computing; D008875:Middle Aged; D012016:Reference Values; D013702:Temporal Lobe / Q000473:pathology