A study published in Current Biology identified differences in infants' brainwaves from as early as six months.

Behavioural symptoms of autism typically develop between a child's first and second birthdays.

Autism charities said identifying the disorder at an earlier stage could help with treatment.

It is thought that one in every 100 children has an autism spectrum disorder in the UK. It affects more boys than girls. While there is no "cure", education and behavioural programmes can help.

One of the researchers, Prof Mark Johnson from Birkbeck College, University of London, told the BBC: "The prevailing view is that if we are able to intervene before the onset of full symptoms, such as a training programme, at least in some cases we can maybe alleviate full symptoms."
His team looked for the earliest signs of autism in 104 children aged between six and 10 months. Half were known to be at risk of the disorder because they had on older sibling who had been diagnosed with autism. The rest were low risk.

Older children with autism can show a lack of eye contact, so the babies were shown pictures of people's faces that switched between looking at or away from the baby.

Sensors attached to the scalp looked for differences in brain activity.

In low-risk babies, or high-risk babies that did not develop autism, there was a large difference in the brainwaves when looking at each type of image.

There was a much smaller difference in the brainwaves of babies who developed autism.

bbc.com