Brain scans in infants shed light on autism onset
February 17th, 2012
08:58 AM ET

Brain scans in infants shed light on autism onset

New research provides evidence that wiring in the brains of children with autism differs from typically developing children as early as six months of age, according to a study published in the American Journal of Psychiatry on Friday.

"This is the earliest study of brain development using neuro-imaging," says Geraldine Dawson, Ph.D. "By six months of age, even before the symptoms [of autism] emerge, the brain networks that connect different brain regions do not develop correctly."

Dawson is not only one of the study authors, she's also the Chief Science Officer of the advocacy group Autism Speaks, which, along with the National Institutes of Health and the Simons Foundation, funded the research.

Researchers at the University of North Carolina at Chapel Hill, along with researchers from other locations of the Infant Brain Imaging Study (IBIS) network, studied 92 babies who were all considered to be at high-risk for developing autism because they had older siblings with the neurodevelopmental disorder. Currently, about one in 110 children in the United States has autism, according to the latest CDC statistics.

All 92 infants underwent a type of MRI (magnetic resonance imaging) scan called diffusion tensor imaging.  MRIs do not use radiation and therefore are safe to use on babies.

Most of the children were scanned again at the age of 12 and 24 months. They were also given standard behavioral assessments for autism when they were 24 months old. After the behavioral assessment, 28 children met the criteria for autism, 64 did not.

When the researchers looked at the 6, 12 and 24-month brain scans, they found differences in the development of white matter fiber tract development – how the neurons in the brain talk to or connect to other parts of the brain – in 12 of 15 major brain connections or pathways.

The 6-month brain scans of children who were later diagnosed with autism revealed that these white matter pathways were growing faster or were more dense compared to those who didn't develop autism. That growth then appears to slow down, so that at 12 months, both groups of children seem to have similar pathway development. By the time the children were 24 months old, the toddlers who developed autism had less dense brain connections than their typically developing counterparts.

Dr. Eric Hollander says these new findings are very important because they suggest brain connectivity plays a central role in autism. Hollander, who is the director of the Autism and Obsessive Compulsive Spectrum Program at Albert Einstein College of Medicine and Montefiore Medical Center, was not involved in the study.

He says the work done by these researchers is very unique and what's really fascinating is that they picked up the differences by studying children over time. Had the children only been studied at a single point, like at 12 months, the difference may not have been evident.

"Usually we are picking up clinical [behavioral] symptoms at 18 months, some say even earlier... clearly they are picking up alterations in white matter as early as 6 months."

Zachary Warren, who also was not involved with the research, describes this new research as "powerful" and "exciting" because he says it's the most impressive data to date that looks at the developing brain over time.

"It provides the best evidence to date that core features of autism are likely related to nerve biological connectivity. This is really compelling evidence that we should be focusing on connection and disconnection in the brain," said Warren, director of the Vanderbilt Kennedy Center Treatment and Research Institute for Autism Spectrum Disorders (TRIAD) at Vanderbilt University.

All the experts, including the study authors, caution that this doesn't mean researchers have found a way to diagnose autism using MRI scans.  The research is far too preliminary to draw that conclusion because it only included children who were known to be at high risk for autism because of their siblings.  Lead study author Jason Wolff says in a statement, "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."

He says this study suggests that autism is a whole brain-phenomenon, rather than any particular brain region.

Dawson says further research needs to include other children, including other high-risk babies like those born prematurely, as well as low-risk babies – to see if the same differences in the development of white matter brain connections are seen. Researchers will also study even younger infants to see how early these brain connections seem to go awry.

Early diagnosis of autism leads to earlier interventions and, because this study identifies problems with the brain's connections before symptoms appear, Dawson is hopeful that this research could lead to earlier interventions.  She says if autism could be identified in infants before symptoms are apparent, they could receive therapies to stimulate early social development and possibly even prevent onset of symptoms.

Dawson says this study helps researchers better understand why children with autism have trouble with communication and social skills.  If different parts of the brain aren't properly connected, it helps explain why children with autism have difficulties developing complex social behaviors and language since multiple parts of the brain are involved at any given time.

Since this is still early research that provides clues to biomarkers for autism which may eventually lead to a clear diagnostic test, it's much too early to suggest regular MRI screenings to determine if a child will have autism.

Until such a test exists, parents are urged to look for early signs of autism, including:
- lack of eye contact
- failure to use gestures
- lack of social play
- child does not respond to its name by age 1

More information for recognizing early signs of autism can be found at www.autismspeaks.org and from the CDC.

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