Laterobasal amygdalar enlargement in 6- to 7-year-old children with autism spectrum disorder.
BACKGROUND
There is substantial imaging evidence for volumetric abnormalities of the amygdala in younger children with autism spectrum disorder (ASD). The amygdala can be divided into functionally distinct laterobasal, superficial, and centromedial subregions. To date, we are not aware of any in vivo reports specifically assessing subregional amygdalar abnormalities in individuals with ASD.


OBJECTIVE
To evaluate alterations in subregional amygdalar morphology in children with ASD compared with typically developing (TD) children and to examine the relationships with ASD symptom severity.


METHODS
A cross-sectional study encompassing a narrow age range of children with ASD and age-matched TD children that evaluated magnetic resonance imaging-defined subregional morphology of the amygdala using a novel subregional analytic method.


METHODS
Participants were recruited and clinically evaluated through the University of Washington Autism Center and imaged at the Diagnostic Imaging Sciences Center at the University of Washington. Imaging data were analyzed through the Brain Imaging Laboratory at the Seoul National University.


METHODS
Fifty-one children 6 to 7 years of age (ASD, n = 31 and TD, n = 20) were assessed using magnetic resonance imaging and behavioral measures.


METHODS
Volume and subregional measures of the amygdala and measures of social and communication functioning.


RESULTS
The ASD group exhibited larger right and left amygdalae, by 12.7% and 11.0%, respectively, relative to the TD group. Subregional analysis revealed that the ASD group had enlarged laterobasal amygdalar subregions, relative to the TD group, after adjusting for age, sex, and hemispheric cerebral volume (P < .05, false discovery rate corrected and with clustered surface points >15). Exploratory analyses revealed that there were linear trends comparing a strictly defined subgroup of children with autistic disorder, who exhibited the greatest extent of laterobasal enlargement, followed by a subgroup of children with pervasive developmental disorder not otherwise specified and then the group of TD children (P for linear trend <.001). There were linear trends between enlargement of laterobasal subregions and lower levels of social and communication functioning (P < .001, P < .001, and P = .001 for 3 areas in the right laterobasal subregion; P < .001 for 1 area in the left laterobasal subregion).


CONCLUSIONS
The current study demonstrates bilateral enlargement of laterobasal subregions of the amygdala in 6- to 7-year-old children with ASD and that subregional alterations are associated with deficits in social and communicative behavior.
Department of Psychiatry, Seoul National University, Seoul, South Korea.
Jieun E
JE
Kim
In Kyoon
IK
Lyoo
Annette M
AM
Estes
Perry F
PF
Renshaw
Dennis W
DW
Shaw
Seth D
SD
Friedman
Dajung J
DJ
Kim
Sujung J
SJ
Yoon
Jaeuk
J
Hwang
Stephen R
SR
Dager
D000367:Age Factors; D000679:Amygdala / Q000473:pathology*; D001921:Brain / Q000254:growth & development / Q000473:pathology; D001931:Brain Mapping / Q000706:statistics & numerical data; D002648:Child; D002657:Child Development / Q000502:physiology; D002659:Child Development Disorders, Pervasive / Q000175:diagnosis / Q000473:pathology*; D003430:Cross-Sectional Studies; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D006984:Hypertrophy / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D015233:Models, Statistical; D011569:Psychiatric Status Rating Scales / Q000706:statistics & numerical data; D012951:Socialization