The new study - published in the Feb. 17 edition of the American Journal of Psychiatry - looked at the brain development of 92 high-risk infants ages 6 to 24 months. The babies were considered high-risk because they all have older brothers or sisters who have been diagnosed with an autism spectrum disorder, said the researchers from the Infant Brain Imaging Study network.
The infants underwent a type of MRI called diffusion tensor imaging at 6 months, 1 year and 2 years of age. With the repeated scans, researchers created 3D pictures that showed changes in white matter - the part of the brain embedded with nerve fibers that help different areas of the brain connect with one another.
What did they find? Researchers saw differences in the brain matter of children who were eventually diagnosed with an autism spectrum disorder by age 2. These children were more likely to show thicker, denser nerve-fiber readings at 6 months - but thinner white matter at age 2.
"These findings raise the possibility of developing imaging markers that could detect risk for autism in advance of actual symptoms, and [to] begin treatment before symptoms begin," study author Geri Dawson, chief science officer at Autism Speaks, told HealthDay.
Study authors caution the findings do not mean that autism can be diagnosed with brain scans, but the research is a step in earlier treatment.
An estimated one in 110 children in the U.S. have an autism spectrum disorder. Behavioral signs of autism include little or no eye contact, lack of interest in peer relationships, delay in spoken language, and persistent fixation on parts of objects.