MRI scans in 40 kindergarten children revealed a link between poor pre-reading skills and the size of a structure that connects two language-processing areas in the brain, the researchers said.
Previous studies have shown that this structure -- called the arcuate fasciculus -- is smaller and less organized in adults with poor reading skills than in those with normal reading ability. But it wasn't known if these differences caused reading problems or resulted from a lack of reading experience.
"We were very interested in looking at children prior to reading instruction and whether you would see these kinds of differences," John Gabrieli, a professor of health sciences and technology and a member of the McGovern Institute for Brain Research at the Massachusetts Institute of Technology, said in an MIT news release.
The study was published in the Aug. 14 issue of the Journal of Neuroscience.
Dyslexia, which affects about 10 percent of Americans, is usually diagnosed in children sometime around second grade. These findings suggest that brain scans could help identify children with dyslexia even before they begin reading, so they can receive help earlier.
It's not clear what causes these brain structure differences, but they could result from both genetic and environmental factors, said Gabrieli, who also is a professor of brain and cognitive sciences at MIT.
The researchers plan to follow groups of children as they progress to second grade in order to determine if the brain structure differences identified in kindergarten predict reading difficulties.
"We don't know yet how it plays out over time, and that's the big question: Can we, through a combination of behavioral and brain measures, get a lot more accurate at seeing who will become a dyslexic child, with the hope that that would motivate aggressive interventions that would help these children right from the start instead of waiting for them to fail?" Gabrieli said.
The U.S. National Institute of Neurological Disorders and Stroke has more about dyslexia.