Clinical and anatomical heterogeneity in autistic spectrum disorder: a structural MRI study.
BACKGROUND
Autistic spectrum disorder (ASD) is characterized by stereotyped/obsessional behaviours and social and communicative deficits. However, there is significant variability in the clinical phenotype; for example, people with autism exhibit language delay whereas those with Asperger syndrome do not. It remains unclear whether localized differences in brain anatomy are associated with variation in the clinical phenotype.


METHODS
We used voxel-based morphometry (VBM) to investigate brain anatomy in adults with ASD. We included 65 adults diagnosed with ASD (39 with Asperger syndrome and 26 with autism) and 33 controls who did not differ significantly in age or gender.


RESULTS
VBM revealed that subjects with ASD had a significant reduction in grey-matter volume of medial temporal, fusiform and cerebellar regions, and in white matter of the brainstem and cerebellar regions. Furthermore, within the subjects with ASD, brain anatomy varied with clinical phenotype. Those with autism demonstrated an increase in grey matter in frontal and temporal lobe regions that was not present in those with Asperger syndrome.


CONCLUSIONS
Adults with ASD have significant differences from controls in the anatomy of brain regions implicated in behaviours characterizing the disorder, and this differs according to clinical subtype.
Toal
F
F
Department of Psychiatry, Royal College of Surgeons in Ireland, Beaumont Hospital, Dublin, Ireland. ftoal@rcsi.ie
Daly
E M
EM
Page
L
L
Deeley
Q
Q
Hallahan
B
B
Bloemen
O
O
Cutter
W J
WJ
Brammer
M J
MJ
Curran
S
S
Robertson
D
D
Murphy
C
C
Murphy
K C
KC
Murphy
D G M
DG
D000293:Adolescent; D000328:Adult; D020817:Asperger Syndrome / Q000453:epidemiology; D001321:Autistic Disorder / Q000453:epidemiology / Q000523:psychology*; D001921:Brain / Q000033:anatomy & histology*; D003072:Cognition Disorders / Q000175:diagnosis / Q000453:epidemiology; D005260:Female; D006801:Humans; D007805:Language Development Disorders / Q000175:diagnosis / Q000453:epidemiology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D009771:Obsessive-Compulsive Disorder / Q000453:epidemiology; D010641:Phenotype; D012720:Severity of Illness Index; D019956:Stereotypic Movement Disorder / Q000453:epidemiology; D055815:Young Adult