(HealthDay News) – The development of white matter pathways is abnormal in infants before manifestations of autism spectrum disorders (ASDs), according to a study published online Feb. 17 in the American Journal of Psychiatry.

Jason J. Wolff, PhD, from the University of North Carolina at Chapel Hill, and colleagues examined white matter fiber tract organization from the ages of 6–24 months in 92 high-risk infant siblings of children with ASD. Participants underwent diffusion tensor imaging at 6 months, and behavioral evaluations at 24 months, at which point 28 infants met the criteria for ASDs and 64 did not.

The researchers found that, compared with infants who did not develop ASDs, those who did develop ASDs had significantly different fractional anisotropy trajectories for 12 of 15 fiber tracts. In the infants with ASDs, development of most fiber tracts was characterized by higher fractional anisotropy values at 6 months, followed by slower change over time compared with infants without ASDs. As a result, by 24 months, the infants with ASDs had lower values.

“This longitudinal study has identified the earliest brain differences related to later symptoms of autism to date. The aberrant development of multiple white matter pathways seen here, along with previously reported brain and behavioral change during infancy, suggests a period of critical importance to the pathogenesis of ASDs,” the authors write.

One author disclosed financial ties to Biospective.

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