A number of studies have indicated brain overgrowth in young children with autism. In a recently published study, researchers used structural MRI at multiple time points through early development to identify which cortical regions show aberrant growth patterns in children diagnosed with autism.

(The paper titled “Longitudinal Magnetic Resonance Imaging Study of Cortical Development through Early Childhood in Autism” was published March 24, 2010 in The Journal of Neuroscience.)

Brain scans were collected in children as young as 12 months old and as old as 6 years old. Most scans were collected in children between 2 years and 5 years old. This was the first study to collect multiple brain scans of individuals across this time period when symptoms of autism become clinically apparent.

The results lumped across both boys and girls show that by 2.5 years of age both the cell mass in the cerebral cortex and the communication lines in the brain’s white matter were significantly enlarged in toddlers with autistic disorder. The most severe enlargement was found in frontal, temporal, and cingulate cortices. On the other hand, the occipital cortex (visual area) developed at normal growth rates.

The study showed that boys with autism had significantly enlarged frontal and temporal lobe gray matter and their cingulate gray matter grew at a nonlinear rate that differed relative to controls. In contrast, abnormal brain growth in autistic girls was more widespread and severe than in boys. Girls demonstrated abnormal growth of the total cerebrum, cerebral white matter, cerebral cortex, frontal lobes, and temporal lobes relative to controls. In addition, girls had enlarged cingulate gray that was not enlarged (but did show an abnormal growth pattern) in boys with autism.


Other related blog posts:

Autism and the Brain: Recent Results from Brain Imaging Studies

Reduced Direct Eye Contact and Autism Spectrum Disorders: Reduced Orientation or Active Avoidance?