A new study reveals that abnormal brain development may be detected in infants as young as 6 months old, long before they begin showing any symptoms of autism.
The study at McGill University in Canada offers new clues for early diagnosis, which can lead to early intervention, researchers say, noting that autism is usually diagnosed around the age of 2 or 3.
“For the first time, we have an encouraging finding that enables the possibility of developing autism risk biomarkers prior to the appearance of symptoms, and in advance of our current ability to diagnose autism,” said co-investigator Dr. Alan Evans at the Montreal Neurological Institute and Hospital at McGill University.
“Infancy is a time when the brain is being organized and connections are developing rapidly,” he continued. “Our international research team was able to detect differences in the wiring by six months of age in those children who went on to develop autism.
“The difference between high-risk infants that developed autism and those that did not was specifically in white matter tract development — fiber pathways that connect brain regions.”
The study followed 92 infants from 6 months to age 2. All were considered at high risk for autism, as they had older siblings with the developmental disorder. Each infant had a special type of MRI scan, known as diffusion tensor imaging, at 6 months and a behavioral assessment at 24 months.
At 24 months, 30 percent of infants in the study were diagnosed with autism. White matter tract development for 12 of the 15 tracts examined differed significantly between the infants who developed autism and those who did not, the researchers noted.
Researchers evaluated fractional anisotropy (FA), a measure of white matter organization based on the movement of water through tissue.
Differences in FA values were greatest at 6 and 24 months, they said.
Early in the study, infants who developed autism showed elevated FA values along these tracts, which decreased over time, so that by 24 months autistic infants had lower FA values than infants without autism.
The study characterizes the dynamic age-related brain and behavior changes underlying autism, vital for developing tools to aid autistic children and their families, the researchers said.
The findings were published in the American Journal of Psychiatry.
Source: McGill University