A test that can identify early signs of autism among babies could emerge from a major new study of the developmental disorder that is being launched tomorrow.

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.

The goal is to identify criteria that can be used to assess very young children’s risk of autism long before its symptoms become obvious. These could then be used to screen infants, so that interventions that might reduce the impact of the condition can begin much earlier than is currently possible.

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 investigate this by investigating babies with an older brother or sister who has autism, who have a significantly raised risk of developing the condition themselves.

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.

The aim is to assess the behaviour of these children at 6, 12 and 18 months, as well as examining their brain activity using a custom-designed “hairnet” that monitors electrical activity. Aside from Birkbeck, five other UK centres are involved.

Professor Mark Johnson, of the Birkbeck Babylab, who is leading the Basis project, said that the aim was to be able to pick up signs of incipient 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 difficulty at the moment is that by the time we are able to confirm a diagnosis of autism, the condition has reached a stage where it is difficult to reverse the symptoms. This study will not only give us early warning signs: it will also tell us a great deal about why autism develops in the way that it does.

“That kind of information will be invaluable in developing therapies to arrest and perhaps even reverse the distressing patterns of atypical behaviour which can blight the lives of families with children with autism.”

Potential interventions include educational programmes aimed at teaching parents how to interact with autistic children, on of which is currently being trialled by a team at the University of Manchester.

Professor Tony Charman, of the Institute of Child Health, who is involved in the Basis project, said: “There is no reason why these interventional approaches should not be helpful for children at a very young age.”

He added that the study could also shed light on cases of autism in which children seem to develop normally, but then regress after 18 months to two years. “It may be that things were not right before, but the differences were very subtle and wouldn’t be picked up in everyday interaction with parents. We hope that studying higher risk children in the first years of life will provide answers about whether there are subtle cues that can be detected early.”

The project is being launched ahead of a major international conference on autism research, which opens in London on Thursday and will be chaired by Professor Charman.

Professor Johnson said that early diagnostic tests and interventions remain several years away. “This is going to be a slow, exhaustive and painstaking process,” he said. “The distinctive differences in babies who may be at risk are likely to be subtle and very difficult to identify by standard behavioural observation. We wouldn’t expect the programme to bear fruit till we have several year’s worth of information on our database.”

Times Recommends

• 'Ghost bus' runs to spare ministers' blushes
• Mobile phones finally passed fit for hospitals
• £6m of sick miners' awards went to union