By Lisa KadaneUpdated Mar 17, 2017
A new study published this week in the journal Nature shows that brain scans of babies as young as a year old can reveal developmental anomalies that point to autism.
The longitudinal study, conducted by researchers across the United States, followed a group of babies over two years and compared MRI scans of their brains at age six months, 12 months and 24 months. The study included 106 infants considered at high risk for developing autism because they had an older sibling with the condition (that risk stands at 20 percent, compared with the general population's risk of one in 68). The study also included 42 low-risk infants.
The brain scans of infants who went on to develop autism by age two (all from the high-risk cohort) showed a hyperexpansion of the cortical surface area—basically, a surge in the folds and grooves of the brain—between six and 12 months. They also showed brain volume overgrowth between 12 and 24 months. The researchers believe it's this initial surge of surface area growth that predicts the development of autism—it then triggers the brain overgrowth that goes hand in hand with behaviours that are hallmarks of autism, such as delayed speech and lack of empathy.
The study will need to be replicated before MRI can actually be used to diagnose autism, but the study’s lead author is optimistic about the findings.
“It’s not a practical tool at this moment, but it shows a lot of promise,” says Heather Cody Hazlett, assistant professor in the department of psychiatry at the University of North Carolina, one of four clinical sites involved in the study. “In a high-risk population, it would be something that could help identify kids even younger, or pre-symptomatically,”
Currently, the earliest autism can be diagnosed is about two years old, as parents begin to notice developmental delays such as slow speech acquisition, or social deficits like avoiding eye contact or refusing to play with other kids. Often, children aren’t diagnosed until age three or four.
“What I think is an interesting piece to come out of the [study] is this idea that you could look at abnormal brain growth as a biomarker that’s pre-symptomatic, before some of the social deficits emerge in that second year,” says Hazlett. “It would be a great time to target intervention.”
The human brain is still very malleable between ages one and two. An early autism diagnosis could potentially alter the way a kid with autism develops—it would enable parents and caregivers to begin therapies to develop language and social skills, for example, in that crucial window.
“You have a greater impact for changing behaviours before they become set,” says Hazlett. “That’s what we’re hypothesizing.”