A just-published study could potentially provide a biomarker for autism. Scientists at the University of North Carolina at Chapel Hill studied young children considered at high risk for autism due to having an autistic sibling. The scientists found notable differences in the brain development of 6-month-old infants who later were diagnosed with autism, as compared to those who did not.

Specifically, the scientists studied 92 infants all of whom had older autistic siblings. The children all had diffusion tensor imaging (a type of magnetic resonance imaging (MRI)) at the age of 6 months and then behavioral assessments at 24 months. In addition, most had additional brain imaging scans at either or both 12 and 24 months. At that point, 28 infants (30 percent) met the criteria for an autism spectrum disorder diagnosis while 64 infants (70 percent) did not. Science Daily explains the differences seen in the brain development of the infants:

The two groups differed in white matter fiber tract development — pathways that connect brain regions — as measured by fractional anisotropy (FA). FA measures white matter organization and development, based on the movement of water molecules through brain tissue.

This study examined 15 separate fiber tracts, and found significant differences in FA trajectories in 12 of the 15 tracts between infants who did develop autism versus infants who did not. Infants who later developed autism had elevated FA at six months but then experienced slower change over time. By 24 months of age, infants with autism had lower FA values than infants without autism.

Jason J. Wolff, PhD, lead author of the study and a postdoctoral fellow at UNC’s Carolina Institute for Developmental Disabilities (CIDD), noted that the study indicates that “autism is a whole-brain phenomenon not isolated to any particular brain region.” He also noted that the study’s findings suggests that autism develops over time in infancy and does not occur suddenly, as has been claimed by some who believe their child became autistic due to a vaccine or other external agent.

Autism, a neurodevelopmental disorder, is currently diagnosed based on the observation and evaluation of professionals using criteria from the Diagnostic Statistical Manual (DSM). The DSM is currently undergoing a controversial revision that could lead to a number of children and adults no longer having an autism diagnosis. A biomarker would seem to provide a straightforward answer about who is autistic.

Wolff also noted that detecting autism earlier could also make it possible to “interrupt” the development of autism in a young child through early intervention. Preventing or even curing autism is also a controversial topic. The extent to which some kinds of early intervention, such as intensive behavioral therapy, can “derail” a child developing autism remains to be seen. Given the number of autistic children who will soon be autistic adults — and the many autistic adults — more resources need also to be dedicated to addressing their needs in such areas as education and, too, employment, housing and long-term care.

The study was published on February 17 in Advance, a section of the website of the American Journal of Psychiatry.

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