Women who stutter have different brain connections than men who stutter; Findings may help explain why more men than women stutter

The research was presented at Neuroscience 2010, the annual meeting of the Society for Neuroscience, held in San Diego.

About five percent of young children stutter, but up to 80 percent of them recover. Of those who don't, most are men; about five times more men than women stutter. These new findings show one difference in brain connections that may explain the striking sex difference in chronic stuttering.

"Girls who continue to stutter past childhood may have greater deficits that are not overcome during development," said lead author Soo-Eun Chang, PhD, of Michigan State University. "Knowing the sex-based differences in brain development that underlie stuttering may help us find sex-specific neural markers for it."

Chang and her colleagues mapped participants' brains using two imaging tools: functional magnetic resonance imaging (fMRI), which showed brain areas active during speech, and diffusion tensor imaging, which provided structural information on connections between brain regions. They tested 18 volunteers who stutter and 14 who don't. The images showed that speakers who stutter had fewer connections between the motor planning and execution areas in the left hemisphere of their brains, as well as increased connections between hemispheres. In addition, the women who stutter had distinctly greater connectivity between the motor and sensory regions in both hemispheres than men who stutter. These findings may indicate that the link between motor control and sensory functions may be abnormal in women who stutter.

"These results need to be replicated in young children to examine whether this is the case at stuttering onset or whether it later appears only in adult females who continue to stutter," Chang said.

Research was supported by the Intramural Research Programs in the National Institute of Neurological Disorders and Stroke and the National Institute on Deafness and other Communication Disorders.