HealthDay News — Infants at high likelihood of autism spectrum disorder (ASD) who are subsequently diagnosed with ASD have significantly faster amygdala growth between 6 and 24 months of age, according to a study published online March 25 in The American Journal of Psychiatry.

Mark D. Shen, Ph.D., from the University of North Carolina at Chapel Hill School of Medicine, and colleagues acquired longitudinal magnetic resonance images at 6 to 24 months in 29 infants with fragile X syndrome, 58 with a high likelihood for ASD who were subsequently diagnosed with ASD, 212 high-likelihood infants who were not diagnosed with ASD, and 109 controls (total of 1,099 scans).

The researchers found that at 6 months, infants who developed ASD had typically sized amygdala volumes, but amygdala growth was significantly faster between 6 and 24 months, such that amygdala volume was significantly larger than that of all other groups by 12 months. There was a significant association for amygdala growth rate between 6 and 12 months with greater social deficits at 24 months when the infants were diagnosed with ASD. Compared with other groups, infants with fragile X syndrome had a persistent and significantly enlarged caudate volume at all ages between 6 and 24 months, which was associated significantly with greater repetitive behaviors.

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“Our research suggests an optimal time to start interventions and support children who are at highest likelihood of developing autism may be during the first year of life,” a coauthor said in a statement.

One author disclosed financial ties to the medical device industry.

Abstract/Full Text