Considerable differences were found in white matter fiber tract development in the brains of high-risk 6 month-old infants who eventually developed symptoms of autism, compared to high-risk infants who did not, researchers from the Infant Brain Imaging Network reported in the American Journal of Psychiatry.

In this text, a “high-risk” infant is one who has an older sibling with autism.

Co-author, Sarah Paterson, PhD, said:

“It’s a tremendously exciting finding. We found that the brains of the children who developed autism were markedly different even prior to the onset of behavioral symptoms of autism. Thus, our findings, while requiring replication, are a very important first step towards identifying a biomarker for autism risk. This would enable specialists to diagnose autism much earlier than what is currently possible through behavioral observations.”

The authors added that autism signs and symptoms do not generally appear suddenly, but rather develop gradually during infancy. The earlier intensive intervention can begin, the better the outcomes tend to be for children with an ASD (autism spectrum disorder).

Paterson said:

“This research raises the possibility that we might be able to intervene even before a child is 6 months old, to blunt or prevent the development of some autism symptoms.”

Paterson and team gathered data on 92 high-risk infants. They all underwent DTI (diffusion tensor imaging); a type of MRI (magnetic resonance imaging), when they were six months old. Their behaviors were assessed when they reached two years of age. The majority of the children also had further brain scans at 12 and/or 24 months.

30% (28 total) of the children were found to have met the criteria for ASD at the age of two years, while 70% (64 of them) didn’t. White matter fiber tract development, as measured by fractional anisotropy (FA), was found to be different between the two groups when imaging scans were done at the age of 6 months. FA measures white matter development and organizations by observing how water molecules more through brain tissue.

The researchers examined 15 different fiber tracts. They found considerable differences in FA growth trajectories in 12 of them; the differences were clear between those who developed autism and those who did not.

FA at six months was elevated among the infants who went on to develop autism. However, development slowed down over time. By the time they were two years old, those with autism had inferior FA values compared to the other children.

A recent study, carried out in London and reported in Current Biology, found different brain responses in high-risk infants who were later diagnosed with the conditions, compared to low-risk ones, or high-risk ones who did not develop autism. In that study, the babies were shown pictures of faces that were either looking at them or looking away.

Paterson says that the two studies together provide more compelling evidence that researchers are successfully identifying markers for diagnosing autism and potential autism earlier on.

Written by Christian Nordqvist