Scientists work on test for autism

The research will look at around 200 infants with autistic older siblings, to seek patterns of early brain development that predict whether they will also develop the condition.

At present, autism is usually diagnosed in the third year of life, but it is thought that much of the altered brain development that influences the condition begins much earlier.

The new British Autism Study of Infant Siblings (Basis) will study this by investigating babies with an older brother or sister who has autism, who have a significantly raised risk of developing the condition themselves.

The goal is to identify signs that can be used to identify very young children's risk of autism long before the symptoms become obvious.

While the chances of developing an autistic spectrum disorder are about one in 100 in the general population, children with autistic older siblings are up to 10 times more likely to be affected.

In the study, which is being managed by the Babylab at Birkbeck, University of London, up to 200 families affected by autism will be recruited so that infants can be studied at regular intervals of development.

Professor Mark Johnson, of the Birkbeck Babylab, who is leading the project, said that the aim was to be able to pick up signs of autism at a very early age.

"In the longer term, the aim is to develop possible interventions that might reduce the number of susceptible babies that go on to develop autism," he said.

The project is being launched ahead of a major international conference on autism research, which opens in London on Thursday.