a grid of 9 brain maps showing activity in different areas of the brain

Brain networks diverge in autism by toddler age | Spectrum | Autism Research News

Wide connections: The salience (top), executive control (center), and standard mode (bottom) networks attract different brain regions in autistic (warm colors) and non-autistic (cool colors) toddlers.

Autistic children from 2 years old show differences in brain network structure of their non-autistic peers, according to a new study. Those differences vary between autistic girls and boys, the study also shows.

Functional brain imaging data is difficult to collect in young children, especially children with autism. Using ‘structural covariance magnetic resonance imaging’ to compare how gray matter density varies in brain regions within a network could serve 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 eye-catching networkinvolved in focusing attention on stimuli, and a larger default mode network, which is active when a person’s attention is turned inward, than those without the condition, Zielinski found in 2012. The new results extend the findings to younger children.

Identifying such differences closer to age at which autism is diagnosed could help elucidate origins of condition, researcher says Christine Wu Nordahlicassociate professor of psychiatry and behavioral sciences at the University of California, Davis, MIND Institute.

“Whenever we see differences in brain structure in older individuals, I will think, ‘Is this really part of the etiology of autism, or is it life that happens to someone with autism?'” Nordahl says. “So it’s helpful to look earlier.”

tThe researchers analyzed brain images of 122 autistic and 122 non-autistic children aged 2 to 4, evenly distributed by gender. Many of the autistic children also have an intellectual disability.

As in the 2012 study, autistic preschoolers 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 regulates cognitive functions needed for everyday tasks. In addition, the primary auditory cortex tended to connect to the salience network only in autistic children, although this finding was not statistically significant.

The differences “intuitively and theoretically correspond to what we see clinically in young people with autism,” such as problems with 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 examined were all more spread out across the brain in girls than in boys, regardless of diagnosis. More brain areas matched the three networks in autistic than non-autistic boys, while fewer brain areas matched the striking and executive networks in autistic girls than non-autistic girls. Girls with autism showed no differences from those without in the standard mode network. The findings are published in NeuroImage in April.

The results underscore the need for more imaging studies in autistic girls, both Nordahl and Zielinski say. “The female story in autism has been under-told,” says Zielinski. “And this is at least an indication that there is a story.”

a grid of 9 brain maps showing activity in different parts of the brain

gender differences: Network brain regions also vary between girls (yellow) and boys (red), regardless of diagnosis; common areas are displayed in orange.

By day 14, neural progenitors of the organoids were continuing to replicate or transitioning into neurons or glial cells. In the organoids derived from the autistic IBIS participants, RNA sequencing suggested that the neural progenitors replicated more frequently, while the cells in the organoids derived from non-autistic children tended to differentiate.

this study is ‘impressive’, says Sulamite Green, assistant clinical professor of psychiatry and biobehavioral sciences at the University of California, Los Angeles, who was not involved in the work. β€œIt is no easy task to get good MRI scans with almost 250 toddlers and preschoolers.”

Some network variations may be missing because the team failed to account for behavioral differences between the autistic children, she says. And it would be helpful to compare the findings with resting-state functional MRI, a more commonly used method.

Findings show interventions may need to occur early in life to be effective, 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, the fact that the toddlers and the adolescents have a similar network structure does not necessarily mean that the networks are “hardwired” at a young age, say both Zielinski and Nordahl. Instead, they probably waver over time.

It is important to investigate whether differences at the network level actually lead to behavioral changes, Supekar says. For example, the salience network does not correlate with autism behavior in gender-specific waysSupekar reported in February.

That question is one of the researchers’ next steps, Nordahl says. They also hope to examine structural covariance in scans of the children of different ages, she says β€” many have now reached adolescence.

Cite this article: https://doi.org/10.53053/VGJZ6432

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