Brain scans of toddlers with autism spectrum disorder (ASD) can help determine which children will have better outcomes as they grow up, a US study shows.
In the first study of its kind, the research team shows that infants with ASD that go on to have good language skills have neural activity in language-sensitive areas of the brain similar to non-ASD children.
The findings, published today in Neuron magazine, may help medical staff and parents in determining what levels of treatment are required for children with ASD and the best time to start working with the children.
Senior author Professor Eric Courchesne, from the University of California, San Diego, says understanding why some toddlers with ASD get better and develop good language has eluded researchers because little is known about the early neural bases of abnormal language development in ASD.
"This is because most brain imaging studies of the disorder have been conducted when ASD subjects are much older and well after early stages of development and after treatment," says Courchesne, director of the Autism Centre of Excellence in the Department of Neuroscience.
For this latest study, brain activity was measured in 60 toddlers with ASD plus 43 non-ASD toddlers, aged between 12-48 months, as they listened to stories while sleeping, a technique pioneered by the team.
The team used functional brain imaging (fMRI) that shows where activity is triggered in the brain by speech stimuli and how strong that activity is.
The researchers then statistically compared maps of the ASD toddler brain activity to each other and to typically developing toddlers.
The children were followed and assessed in early childhood, on average one year after the initial fMRI to determine which toddlers had better language outcomes.
Courchesne says the study discovered "two distinctly different and early appearing brain subtypes of ASD".
"Toddlers with ASD who go on to have good language have near-normal neural activity in language-sensitive brain regions," says Courchesne.
"Toddlers with ASD who have a poor outcome have little to no such activity in those regions. Their brain does not respond to language."
Co-author Dr Karen Pierce, co-director of the UC San Diego Autism Center of Excellence: says the functional activation patterns could serve to signify treatment readiness.
"If a toddler with autism spectrum disorder is detected with strong brain activation in language areas, then I would predict that this toddler would excel in treatment and have a good long-term outcome," she says.
"On the other hand, if a toddler showed poor activation in language cortex, then this might be a red flag for parents and clinicians and could imply that the child might require considerably enhanced treatments specifically designed to stimulate weak language function in the brain."