MRI scans have revealed a key growth pattern in the brains of infants that researchers have correlated with autism spectrum disorder.
After examining brain scans from more than 400 infants (6-24 months of age), researchers found that children who were eventually diagnosed with autism spectrum disorder (ASD) had something in common: overgrowth of the amygdala.
Located deep in the brain, the amygdala plays a key role in processing memory, emotional responses and decision making. An abnormally large amygdala is common among school-aged children with ASD, but exactly when overgrowth starts to occur has been unclear.
“The vast majority of neuroimaging studies are cross-sectional and are conducted on children after diagnosis (i.e., 2 years of age and older), leaving unknown the developmental time course of amygdala enlargement, how it relates to the timing of emerging diagnostic features and eventual diagnosis, and whether enlargement is specific to the amygdala or also occurs during infancy in other subcortical structures, such as the basal ganglia,” first author Mark Shen, PhD, assistant professor of psychiatry and neuroscience at UNC Chapel Hill, and colleagues explained.
With the goal of identifying a clearer idea of when the amygdala overgrowth starts to occur, researchers acquired longitudinal brain MRIs from four groups of children—29 infants with fragile X syndrome, 58 infants at high likelihood for ASD who were later diagnosed, 212 high-likelihood infants not yet diagnosed with ASD and 109 control infants.
Researchers found that in infants who developed ASD, amygdala size was typical at 6 months of age, but this changed between the ages of 6 and 24 months. By 12 months the ASD group exhibited significantly larger amygdala volume compared to the other groups.
These changes appeared to correlate with the progression of social deficits as well. The experts reported that amygdala growth rate between 6 and 12 months was associated with greater social deficits at 24 months, when the children were diagnosed with ASD.
“The faster the amygdala grew in infancy, the more social difficulties the child showed when diagnosed with autism a year later,” the researchers said.
The authors note that their study results, which are the first to identify amygdala overgrowth before the onset of behavioral symptoms in autism, could help improve treatment and therapy strategies for children on the spectrum.
“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,” the experts suggested. “The focus of a pre-symptomatic intervention might be to improve visual and other sensory processing in babies before social symptoms even appear.”
The detailed research can be viewed in the American Journal of Psychiatry.
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In addition to her background in journalism, Hannah also has patient-facing experience in clinical settings, having spent more than 12 years working as a registered rad tech. She joined Innovate Healthcare in 2021 and has since put her unique expertise to use in her editorial role with Health Imaging.