Autism linked to unusual brain growth

Autism may be linked to small head circumference at birth followed by unusually rapid growth during the first year of life, researchers have found.

Autism affects one in every 160 children and is a serious neurological disorder. The study, carried out at the University of California, San Diego (UCSD) School of Medicine, hoped to find ways of diagnosing the disorder in the first year of life to help treat the children earlier and improve their future.

They found an abnormally accelerated rate of head, and therefore brain, growth occurs well before the first clinical signs of autism. Currently the disease is not detected until children are aged between two and four and is diagnosed through behavioural signs such as delayed speech and unusual social and emotional reactions.

The researchers believe that rapid, excessive brain growth in infants with autism does not allow enough time for accumulation of experiences and emotions that guide and shape normal behaviour.

The study's senior author Eric Courchesne explained during the important first year of learning the brains of children with autism are growing too fast. 'Without the guidance of experience and learning, the brain may be creating abnormal connections that make it very hard for autistic children to make sense of the world they live in,' he said.

Comparisons with children free of signs of autism showed that on average, the children's head size was in the bottom 25% at birth. But by the time they had reached the age of 12-14 months, their average head size was in the top 15%. From then on, brain growth slowed.

At present, it is not known what causes this sudden spurt of growth.

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