Evidence of Brain Overgrowth in the First Year of Life in Autism Courchesne
E, Carper R, Akshoomoff N Abstract: JAMA. 2003 Jul 16;290(3):337-44 Findings In children with autism, scientists have not yet found any early warning signs of abnormal neurological changes. When clinical signs of autism first appear, ususally at 2 to 3 years of life, scientists have reported increases in brain volume and head circumferences (HCs). Drs. Courchesne and his colleagues suggested that brain increases could be occurring earlier, perhaps before the first clinically noticeable behavioral symptoms, changes which may be related to outcomes in early childhood. To test this, they studied medical records of 48 children with autism spectrum disorder (ASD), aged 2 to 5 years who had undergone MRI scans. Of these 48 children, 15 had head circumference measurements taken at birth, 1-2 months, 3-6 months, and 6-14 months, 7 had measurements at birth and 6 to 14 months, and 28 had measurements at birth only. Compared with typically developing children infants with ASD had smaller HCs at birth, but after birth growth accelerated in the autism group and significant differences in HC were found by 6-14 months. This increase was related to greater cerebral cortex volume.
Conclusions Before doctors first see any clinical signs of autism, there appear to be 2 phases of brain growth abnormality in these children. First, there is a reduced head size at birth compared with typically developing children and second, there appears to be a sudden excessive increase in head size between 1-2 months and again at 6-14 months. Such increased rate of head growth during infancy may be an important physical symptom of this disorder. Such measurable neurological warning signs could lead to objective, quantifiable, and reliable clinical tests for autism. This would allow doctors to begin treatments earlier.
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