Towards a neuroanatomy of autism: a systematic review and meta-analysis of structural magnetic resonance imaging studies.
BACKGROUND
Structural brain abnormalities have been described in autism but studies are often small and contradictory. We aimed to identify which brain regions can reliably be regarded as different in autism compared to healthy controls.


METHODS
A systematic search was conducted for magnetic resonance imaging studies of regional brain size in autism. Data were extracted and combined using random effects meta-analysis. The modifying effects of age and IQ were investigated using meta-regression.


RESULTS
The total brain, cerebral hemispheres, cerebellum and caudate nucleus were increased in volume, whereas the corpus callosum area was reduced. There was evidence for a modifying effect of age and IQ on the cerebellar vermal lobules VI-VII and for age on the amygdala.


CONCLUSIONS
Autism may result from abnormalities in specific brain regions and a global lack of integration due to brain enlargement. Inconsistencies in the literature partly relate to differences in the age and IQ of study populations. Some regions may show abnormal growth trajectories.
Stanfield
Andrew C
AC
Division of Psychiatry, School of Molecular and Clinical Medicine, University of Edinburgh, Royal Edinburgh Hospital, Edinburgh, UK. andrew.stanfield@ed.ac.uk
McIntosh
Andrew M
AM
Spencer
Michael D
MD
Philip
Ruth
R
Gaur
Sonia
S
Lawrie
Stephen M
SM
D000367:Age Factors; D000679:Amygdala / Q000473:pathology; D001321:Autistic Disorder / Q000175:diagnosis / Q000473:pathology*; D001921:Brain / Q000473:pathology*; D002421:Caudate Nucleus / Q000473:pathology; D002531:Cerebellum / Q000473:pathology; D003337:Corpus Callosum / Q000473:pathology; D004292:Dominance, Cerebral / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007360:Intelligence / Q000502:physiology; D008279:Magnetic Resonance Imaging; D012737:Sex Factors