Trajectories of early brain volume development in fragile X syndrome and autism.
OBJECTIVE
To examine patterns of early brain growth in young children with fragile X syndrome (FXS) compared with a comparison group (controls) and a group with idiopathic autism.


METHODS
The study included 53 boys 18 to 42 months of age with FXS, 68 boys with idiopathic autism (autism spectrum disorder), and a comparison group of 50 typically developing and developmentally delayed controls. Structural brain volumes were examined using magnetic resonance imaging across two time points, at 2 to 3 and again at 4 to 5 years of age, and total brain volumes and regional (lobar) tissue volumes were examined. In addition, a selected group of subcortical structures implicated in the behavioral features of FXS (e.g., basal ganglia, hippocampus, amygdala) was studied.


RESULTS
Children with FXS had larger global brain volumes compared with controls but were not different than children with idiopathic autism, and the rate of brain growth from 2 to 5 years of age paralleled that seen in controls. In contrast to children with idiopathic autism who had generalized cortical lobe enlargement, children with FXS showed specific enlargement in the temporal lobe white matter, cerebellar gray matter, and caudate nucleus, but a significantly smaller amygdala.


CONCLUSIONS
This structural longitudinal magnetic resonance imaging study of preschoolers with FXS observed generalized brain overgrowth in children with FXS compared with controls, evident at age 2 and maintained across ages 4 to 5. In addition, different patterns of brain growth that distinguished boys with FXS from boys with idiopathic autism were found.
University of North Carolina at Chapel Hill and the Carolina Institute for Developmental Disabilities, NC 27599-2267, USA. heather_cody@med.unc.edu
Heather Cody
HC
Hazlett
Michele D
MD
Poe
Amy A
AA
Lightbody
Martin
M
Styner
James R
JR
MacFall
Allan L
AL
Reiss
Joseph
J
Piven
D000367:Age Factors; D000679:Amygdala / Q000473:pathology; D001479:Basal Ganglia / Q000473:pathology; D001921:Brain / Q000473:pathology*; D001933:Brain Stem / Q000473:pathology; D002421:Caudate Nucleus / Q000473:pathology; D002531:Cerebellum / Q000473:pathology; D002540:Cerebral Cortex / Q000473:pathology; D002659:Child Development Disorders, Pervasive / Q000175:diagnosis / Q000473:pathology*; D002675:Child, Preschool; D015897:Comorbidity; D002658:Developmental Disabilities / Q000175:diagnosis / Q000473:pathology; D004292:Dominance, Cerebral / Q000502:physiology; D005600:Fragile X Syndrome / Q000175:diagnosis / Q000473:pathology*; D006624:Hippocampus / Q000473:pathology; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D007223:Infant; D007360:Intelligence / Q000502:physiology; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D009483:Neuropsychological Tests; D012016:Reference Values