Cross-sectional study of abnormal amygdala development in adolescents and young adults with bipolar disorder.
BACKGROUND
In vivo imaging studies in adult bipolar patients have suggested enlargement of the amygdala. It is not known whether this abnormality is already present early in the illness course or whether it develops later in life. We conducted a morphometric MRI study to examine the size of specific temporal lobe structures in adolescents and young adults with bipolar disorder and healthy control subjects, as well as their relationship with age, to examine possible neurodevelopmental abnormalities.


METHODS
Subjects included 16 DSM-IV bipolar patients (16 +/- 3 years) and 21 healthy controls (mean age +/- SD = 17 +/- 4 years). Measures of amygdala, hippocampus, temporal gray matter, temporal lobe, and intracranial volumes (ICV) were obtained.


RESULTS
There was a trend to smaller left amygdala volumes in patients (mean volumes +/- SD = 1.58 +/- .42 mL) versus control subjects (1.83 +/- .4 mL; F = 3.87, df = 1,32, p = .06). Bipolar patients did not show significant differences in right or left hippocampus, temporal lobe gray matter, temporal lobe, or right amygdala volumes (analysis of covariance, age, gender, and ICV as covariates, p > .05) compared with healthy control subjects. Furthermore, there was a direct correlation between left amygdala volumes and age (r =. 50, p = .047) in patients, whereas in healthy controls there was an inverse correlation (r = -.48, p = .03).


CONCLUSIONS
The direct correlation between left amygdala volumes and age in bipolar patients, not present in healthy control subjects, may reflect abnormal developmental mechanisms in bipolar disorder.
Chen
Barbara K
BK
Department of Psychiatry, The University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229-3900, USA.
Sassi
Roberto
R
Axelson
David
D
Hatch
John P
JP
Sanches
Marsal
M
Nicoletti
Mark
M
Brambilla
Paolo
P
Keshavan
Matcheri S
MS
Ryan
Neal D
ND
Birmaher
Boris
B
Soares
Jair C
JC
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000679:Amygdala / Q000254:growth & development / Q000473:pathology*; D000704:Analysis of Variance; D001714:Bipolar Disorder / Q000473:pathology*; D001921:Brain / Q000473:pathology; D001931:Brain Mapping; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D012737:Sex Factors