Autism is a syndrome that includes problems with social development and communication, and symptoms begin to occur between 1 and 3 years old. Diagnosis is based on behavior, but this may change as researchers have spotted a brain change that could be used as an imaging biomarker for the very early stages of autism.
The study looked at 92 6-month old babies who all had older brothers or sisters with autism and so were at high risk for developing autism. Their brains were imaged using diffusion tensor imaging (a type of magnetic resonance imaging or MRI), and then they had behavioral assessments at 24 months, with some having extra scans at 12 and/or 24 months. At 2 years old, about 30 percent of the children showed behavioral symptoms that suggested autism spectrum disorder.
The scans measured the organization and development of the white matter in the brain, using a technique known as fractional anisotropy (FA). The white matter carries messages between different parts of the brain, and the infants that went on to develop autism scored higher on the FA scale at 6 months but had lower values at 24 months.
"It's a promising finding," said Jason Wolff, Ph.D., lead author of the study and a postdoctoral fellow at the University of North Carolina at Chapel Hill's Carolina Institute for Developmental Disabilities (CIDD). "At this point, it's a preliminary albeit great first step towards thinking about developing a biomarker for risk in advance of our current ability to diagnose autism.
"Autism numbers have been seen to be increasing over the past few decades, but this may just be because of improvements in diagnoses, and an imaging biomarker would make diagnosis more objective. Biomarkers that could diagnose autism earlier could also help with support for parents and children, and could even lead to new targets for therapy development, either pharmaceutical or educational.
"We were surprised that there were so many differences so early in infancy," co-author Dr. Kelly Botteron, who is leading the effort at the Washington University School of Medicine study site in St. Louis, told News Medical. "As this study moves forward, we may want to scan babies at even younger ages so that we can try to see how early this pattern is emerging."
As this study suggests that autism does not just appear in young children but is something that develops slowly from infancy, from 6 months or even earlier, this could be another nail in the coffin for the already-discounted vaccine hypothesis.