Amygdala and hippocampal volumes in adolescents and adults with bipolar disorder.
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.
Blumberg
Hilary P
HP
Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut, USA. hilary.blumberg@yale.edu
Kaufman
Joan
J
Martin
Andres
A
Whiteman
Ronald
R
Zhang
Jane Hongyuan
JH
Gore
John C
JC
Charney
Dennis S
DS
Krystal
John H
JH
Peterson
Bradley S
BS
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