Abnormal brain structure is the latest suspect for researchers looking for a cause for autism. Scientists in the US have found that some stunted regions of the brain may be to blame for the most severe symptoms of the condition, while other undersized regions may cause the milder symptoms often suffered by close relatives of autistics.
Wendy Kates and her colleagues at Johns Hopkins School of Medicine in Baltimore, Maryland, used magnetic resonance imaging to look at the brains of 7-year-old identical twins. One of the boys had classical autism, while his twin had some of the symptoms of autism, including language and social problems. Kates says that about half of all close relatives of autistic children have these milder symptoms.
When the researchers compared the brain scans of the two boys, they found several differences. The amygdala, a structure involved in emotion, and the hippocampus, important for learning and memory, were about half the size in the autistic child compared with his twin brother. The cerebellum and the caudate nucleus, thought to be involved in shifting attention from one task to another, were also significantly smaller (Annals of Neurology, vol 43, p 782).
Author: Alison Motluk, London
New Scientist issue 13 June 1998, page 11
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