Thursday, May 27, 2010

fMRI scanning of babies can diagnose autism as young as 14 months

From the Wall Street Journal:

By taking scans of sleeping children, researchers are discovering what occurs in the brains of babies and young children with autism.

Using functional magnetic resonance imaging, or fMRI, to peer at images of the children's brains, researchers from the University of California, San Diego, found that autistic children as young as 14 months use different brain regions than youngsters with more typical development when hearing bedtime stories.

The findings suggest that even very early on, the brains of those with autism work differently than typical babies. They also help explain why failure of language comprehension is a "red flag" for babies with autism, according to the study's author, Eric Courchesne, director of the UCSD Autism Center of Excellence.

The small study of 43 subjects, believed to be the first to examine the brains of young children with autism and related disorders, was presented at the International Meeting for Autism Research in Philadelphia last week.

This type of work "is going to tell us an awful lot about how the brain goes wrong in the first place and then gives us insight into how we'll be able to help at an earlier age," says Dr. Courchesne.

Learning when and where brain changes occur can also help rule out some suspected causes of autism. For instance, if brain differences are already present at birth, then environmental toxins or vaccine exposure in childhood can't be responsible, according to Dr. Courchesne.

Regular MRIs examine the structure of the brain, but by asking subjects to perform a task in the scanner, an fMRI can examine brain function through blood flow and response in response to neural activity. Unlike X-rays, they don't use radiation.

But scientists have had trouble figuring out how to get young children to lie still in the noisy, claustrophobic brain scanners. The UCSD group came up with a solution: Put babies and children in the scanner in the wee hours of the night when they are naturally asleep.

For their study, the researchers first had to find children with autism-spectrum disorders. UCSD recruited 150 pediatricians in and around San Diego to screen 16,000 babies to find nearly 100 who appeared to their doctors to have autism or related disorders.

The researchers brought 23 young children ranging from age 13 months to nearly 4 years old with autism-spectrum disorders, and 20 typically developing kids to the lab at nighttime when the children were already asleep.

While the children were in the scanner, researchers played a repeating tape of a female voice reading a bedtime story and the scanner recorded the children's brain activity. (Dr. Courchesne's lab has shown in a separate, published study of older children that even when children sleep, they hear and react to language.)

This study showed that in the typically developing babies, both the right and left temporal regions of the brain—parts that help us understand different aspects of language—were activated. In older children, there was evidence that the left side became even more active compared with the right side.

But in the babies and children with autism-spectrum disorders the use of the right brain was far stronger.

The left temporal region of the brain usually deals with understanding the meaning of words, in a "dictionary" manner, he says. The right side helps us understand social language based on context, like how people sound when they are angry rather than happy, even if they're speaking the same words.

One theory is that in autism, the right side is needed to learn the basic definitions of words, crowding out the ability to develop skills to process more social, nuanced aspects of language, Dr. Courchesne says.

The research could one day help clinicians diagnose children more reliably and younger than 2 or 3 years old, the age when they currently are consistently diagnosed, according to David Mandell, a psychiatry and pediatrics professor at University of Pennsylvania and scientific chair of the autism meeting, who wasn't involved with the study.

Drs. Courchesne and Mandell say that the scanning technique isn't ready for that yet.