Autism signs appear in brains of six-month-old babies

The early signs of autism can be detected in babies as young as six months, a new study has found, suggesting future treatments could be given at this time to lessen the impact of the disorder on children.

Researchers at University of North Carolina who looked at how the brain develops in early life found that tracts of white matter that connect different regions of the brain did not form as quickly in children who later developed autism, compared with kids who didn't develop the disorder.

"The way the wiring was changing was dampened" in the children with autism, said study researcher Jason Wolff.

"It was a more blunted change over time, in how the brain was being wired," Wolff was quoted as saying by LiveScience.

In contrast, in the brains of infants who did not later develop autism, white matter tracts were swiftly forming, he said. "Their brains were organising themselves in a pretty rapid fashion."

The findings, published in the American Journal of Psychiatry, suggest that during a child's first year, "there is a potential to intervene, to disrupt autism before it becomes entrenched," Wolff said. "There are a lot of possibilities to improve outcomes for these children."

The first year of life is an important time in brain development, and is also when the first symptoms of autism start to appear, Wolff said. In the study, the researchers looked at the brains of 92 infants, when they were six months, one year and two years old. All of the children had a sibling with autism; research shows such children have a higher risk of developing the disorder themselves.

The researchers used a brain scan called diffusion tensor imaging, a type of MRI scan which allowed them to see changes in the brain's organisation over time.

When the kids were two years old, 28 developed autism, while 64 didn't. Then, the researchers looked back at the early brain scans, to see if there were differences between the groups.

"We looked at pathways that connect brain regions to each other, and 12 out of 15 were different in kids with autism," Wolff said.

Previous studies have found differences in brain volume in infants of this age, and other researchers have looked at white matter tracts in older children with autism, but these structures were not being examined in infants before.

The fact that so many of the tracts were affected shows that autism is a "whole-brain phenomenon," Wolff said. "There are widespread differences" in the brains of people with the disorder, he said.

As to what might be causing these brain differences, it's too early to say, Wolff said. But the findings are consistent with what researchers suspect about what triggers autism's development, "there's a complex interaction between genes, and a child's experiences with the world," he said.

And while the brain scans of the two groups of children certainly revealed their differences, those scans are not at the point where they could be used to diagnose the disorder in a six-month-old, he emphasised.

However, the findings help researchers better understand how the disorder develops. he said.