MRI may shed light into minds of autistic children
Toddlers with autism appear more likely to have an enlarged amygdala which appears to be associated with the ability to share attention with others, a fundamental ability thought to predict later social and language function in children with autism, according to a report in the May issue of Archives of General Psychiatry.
"Converging evidence from MRI, head circumference and postmortem studies suggests that brain volume enlargement is a characteristic feature of autism, with its onset most likely occurring in the latter part of the first year of life," the authors wrote. On the basis of its function and studies of changes in its structure, the amygdala has been identified as a brain area potentially associated with autism.
Matthew W. Mosconi, PhD, and colleagues at the University of North Carolina at Chapel Hill conducted an MRI study involving 50 autistic children and 33 control children. Participating children underwent brain scans along with testing of certain behavioral features of autism at ages two and four. This included a measure of joint attention, which involves following another person's gaze to initiate a shared experience.
Compared to control children, those children with autism were more likely to have amygdala enlargement both at these ages. "These findings suggest that, consistent with a previous report of head circumference growth rates in autism and studies of amygdala volume in childhood, amygdala growth trajectories are accelerated before age two years in autism and remain enlarged during early childhood," the authors wrote. "Moreover, amygdala enlargement in two-year-old children with autism is disproportionate to overall brain enlargement and remains disproportionate at age four years."
Among children with autism, amygdala volume was associated with an increase in joint attention ability at age four, suggesting that alterations to this brain structure may be associated with a core deficit of autism, the authors noted.
"The amygdala plays a critical role in early-stage processing of facial expression and in alerting cortical areas to the emotional significance of an event," Mosconi and colleagues wrote. "Amygdala disturbances early in development, therefore, disrupt the appropriate assignment of emotional significance to faces and social interaction."
Continued follow-up of research participants, now under way, will help determine whether amygdala growth rates continue at the same rate or undergo another period of accelerated growth or a period of decelerated growth in autistic children after age four, the researchers said.
Grants from the National Institutes of Health (NIH) funded the research.
"Converging evidence from MRI, head circumference and postmortem studies suggests that brain volume enlargement is a characteristic feature of autism, with its onset most likely occurring in the latter part of the first year of life," the authors wrote. On the basis of its function and studies of changes in its structure, the amygdala has been identified as a brain area potentially associated with autism.
Matthew W. Mosconi, PhD, and colleagues at the University of North Carolina at Chapel Hill conducted an MRI study involving 50 autistic children and 33 control children. Participating children underwent brain scans along with testing of certain behavioral features of autism at ages two and four. This included a measure of joint attention, which involves following another person's gaze to initiate a shared experience.
Compared to control children, those children with autism were more likely to have amygdala enlargement both at these ages. "These findings suggest that, consistent with a previous report of head circumference growth rates in autism and studies of amygdala volume in childhood, amygdala growth trajectories are accelerated before age two years in autism and remain enlarged during early childhood," the authors wrote. "Moreover, amygdala enlargement in two-year-old children with autism is disproportionate to overall brain enlargement and remains disproportionate at age four years."
Among children with autism, amygdala volume was associated with an increase in joint attention ability at age four, suggesting that alterations to this brain structure may be associated with a core deficit of autism, the authors noted.
"The amygdala plays a critical role in early-stage processing of facial expression and in alerting cortical areas to the emotional significance of an event," Mosconi and colleagues wrote. "Amygdala disturbances early in development, therefore, disrupt the appropriate assignment of emotional significance to faces and social interaction."
Continued follow-up of research participants, now under way, will help determine whether amygdala growth rates continue at the same rate or undergo another period of accelerated growth or a period of decelerated growth in autistic children after age four, the researchers said.
Grants from the National Institutes of Health (NIH) funded the research.