Brain networks diverge in early childhood autism | Spectrum
Extended Connections: The salience (top), executive control (middle) and default mode (bottom) networks attract different brain regions in autistic (warm colors) and non-autistic (cool colors) toddlers.
Autistic children as young as 2 show differences in brain network structure of their non-autistic peers, according to a new study. These differences vary between girls and boys with autism, the study also shows.
Functional brain imaging data is difficult to collect in young children, especially in autistics. Using ‘structural covariance magnetic resonance imaging’ to compare variation in gray matter density across brain regions within a network can act as a proxy, says lead researcher Brandon Zielinskiassociate professor of pediatrics and neurology at the University of Utah in Salt Lake City.
According to this measure, adolescents with autism have a smaller salience networkwhich is involved in directing attention to stimuli, and a larger default mode network, which is active when a person’s attention is focused inward, than those without the condition, Zielinski discovered in 2012. The new results extend the findings to younger children.
Identifying these differences closer to the age at which autism is diagnosed may help elucidate the origins of the condition, a study researcher says. Christine Wu Nordahlassociate professor of psychiatry and behavioral sciences at the University of California, Davis, MIND Institute.
“Whenever we see differences in brain structure in older people, I think, ‘Is this really part of the etiology of autism, or does life happen to an autistic person?’ “, Says Nordahl. “So it is useful to look earlier.”
Jhe researchers analyzed the brain images of 122 autistic children and 122 non-autistic children aged 2 to 4 years, divided equally by sex. Many children with autism also have intellectual disabilities.
Similar to the 2012 study, preschoolers with autism have a smaller salience network and a larger default mode network than those without the condition, the team found. They also have a smaller executive control network, which governs the cognitive functions necessary for daily tasks. Additionally, the primary auditory cortex tended to connect to the salience network in autistic children only, although this finding was not statistically significant.
The differences “intuitively and theoretically align with what we see clinically in young people with autism,” such as difficulties in executive functioning and sensory processing, says Janet Lainhartprofessor of psychiatry at the University of Wisconsin-Madison, who was an investigator on the 2012 study but was not involved in the new work.
The networks studied were all more distributed in the brain in girls than in boys, regardless of the diagnosis. More brain regions aligned to the three networks in autistic boys than in non-autistic boys, while fewer brain regions aligned to the salience and executive networks in autistic girls than in non-autistic girls. Girls with autism showed no difference from those without in the default mode network. The findings were published in NeuroImage in April.
The findings underscore the need for more imaging studies in autistic girls, say Nordahl and Zielinski. “The story of the woman in autism has been under-told,” Zielinski says. “And that’s at least an indication that there’s a story there.”
Gender differences: The brain regions of the network also vary between girls (yellow) and boys (red) regardless of the diagnosis; the common areas appear in orange.
Jstudy is “impressive”, says Shulamite Green, assistant clinical professor of psychiatry and biobehavioral sciences at the University of California, Los Angeles, who was not involved in the work. “It’s no small feat to get good MRI scans with nearly 250 toddlers and preschoolers.”
Some network variations may be missing because the team did not account for behavioral differences between autistic children, she says. And it would be useful to compare the results with resting-state functional MRI, a more commonly used method.
Findings show interventions may need to take place early in life to have an effect, says Kaustubh Supekarclinical associate professor of psychiatry and behavioral sciences at Stanford University in California, who was not involved in the work.
“The differences are pronounced,” he says. “That means we have to go earlier than 3 years to do something about it.”
However, just because toddlers and teens have a similar network structure doesn’t necessarily mean the networks are “hard-wired” at a young age, Zielinski and Nordahl say. On the contrary, they probably falter over time.
It will be important to determine whether network-level deviations actually lead to behavioral changes, Supekar said. The salience network, for example, is not correlated with autistic behaviors gender-specificSupekar reported in February.
That question is part of the researchers’ next steps, Nordahl says. They also hope to examine structural covariance in scans of children at different ages, she says – many have now reached adolescence.
Cite this article: https://doi.org/10.53053/VGJZ6432