A preliminary longitudinal volumetric MRI study of amygdala and hippocampal volumes in autism.
BACKGROUND
Previous studies suggest that amygdala volume, when compared with healthy controls, is increased in young children with autism, is unchanged in cohorts of older youth, and is smaller in adults. Hippocampal volume, however, does not appear to have age-related changes, and it is unclear whether individuals with autism have volumetric differences in this structure. The goal of this pilot investigation is to characterize the developmental trajectories of the amygdala and hippocampus in children with autism between the ages of 8 and 14years and to examine clinical correlates of volume change.


METHODS
Twenty-three children with autism and 23 controls between the ages of 8 and 12 underwent a magnetic resonance imaging procedure of the brain (T1-weighted) at two time points. Nine children with autism and 14 controls had good quality scans from both time points; however, all usable scans from all subjects (15 children with autism and 22 controls) were included in a mixed effect analysis. Regression models were used to estimate group differences in amygdala and hippocampal volumes. Changes in amygdala and hippocampal volumes (Time 2-Time 1) were correlated with clinical severity measures.


RESULTS
Amygdala volume changes with time were similar between the two groups. Within the autism group, right amygdala volume change was correlated with the ability to establish appropriate eye contact. Right hippocampal volume was significantly increased in the autism group when compared with controls. Differences in right hippocampal volume change with time between the two groups approached significance.


CONCLUSIONS
This study provides preliminary evidence of normalization of amygdala volumes in late childhood and adolescence. It also suggests that hippocampal volumetric differences may exist in autism in late childhood and adolescence.
Center for Interdisciplinary Brain Sciences Research, Department of Psychiatry and Behavioral Sciences, Stanford, United States.
Naama
N
Barnea-Goraly
Thomas W
TW
Frazier
Lucia
L
Piacenza
Nancy J
NJ
Minshew
Matcheri S
MS
Keshavan
Allan L
AL
Reiss
Antonio Y
AY
Hardan
D000293:Adolescent; D000679:Amygdala / Q000473:pathology*; D000704:Analysis of Variance; D001321:Autistic Disorder / Q000473:pathology*; D002648:Child; D005260:Female; D006624:Hippocampus / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male
Amygdala; Autism; Autism Diagnostic Interview (ADI); Autism Diagnostic Observation Schedule (ADOS); Autism Spectrum Disorders (ASD); Full-scale IQ (FSIQ); Hippocampus; Socioeconomic status (SES); Total Brain volume (TBV)