Twin Study Reveals Smaller Brain Regions In Autistic Children

John johnhkm at
Thu Sep 9 00:08:46 EST 1999

Twin Study Reveals Smaller Brain Regions In Autistic Children

In the first published brain imaging study of autism in identical twins,
scientists have identified brain regions that are abnormally small in
children with autism. Their report appears in the June issue of the Annals
of Neurology, the scientific journal of the American Neurological

These results appear to support a recent theory that there is a mild form of
autism in relatives of autistic children that derives from some of the same
genetic abnormalities that lead to severe autism.

"It's one pair of twins," cautions Wendy R. Kates, Ph.D., assistant
professor of psychiatry at Johns Hopkins University School of Medicine and
research psychologist at the Kennedy Krieger Institute at Johns Hopkins
University, one of the authors of the study. "The results are very
preliminary and they need to be replicated on a larger scale."

But the results are promising enough that the National Alliance for Autism
Research and the Autism Society of America are funding a larger follow-up
study that will compare 10 identical-twin pairs in which one sibling has
autism and the other exhibits less severe, yet similar, language and social

Kates and her colleagues from Kennedy Kreiger Institute, Johns Hopkins
University, and Stanford University found that, compared to his brother, the
autistic twin had a smaller amygdala, a structure involved in emotion, and a
smaller hippocampus, an area critical for learning and memory. They also
found that parts of the cerebellum that are involved in shifting attention
from one task to another were reduced in size.

Relative to the normal boys, both twins had reduced frontal cortex, an area
responsible for organizing, planning, and problem-solving, and a reduced
superior temporal gyrus, a region responsible for processing language.


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