For the first time, researchers have spotted unique features of the brain anatomy of stutterers. The findings could help predict who is at risk for stuttering and perhaps lead to treatments based on the particular features of a stutterer's brain.
A team led by neurologist Anne Foundas at Tulane University Health Science Center in New Orleans, Louisiana, used magnetic resonance imaging to measure the volume of speech-related brain regions in 13 men and three women who had stuttered since childhood, and in a control group of 16 nonstutterers. The controls were matched for sex (male stutterers outnumber females 4 to 1) and handedness (stutterers are about twice as likely to be lefties), as well as age and education. The researchers then compared two brain areas associated with speech and language--Broca's area in the front of the brain, and parts of Wernicke's area in the back.
The stutterers had a much larger and more symmetric planum temporale, a region in Wernicke's area associated with language and music processing, the team reports in the July issue of Neurology. Ordinarily, this feature juts out more on the left side in right-handers. Stutterers also had more folds on the brain surface in Broca's area, which Foundas suggests could disrupt connections between the auditory and motor areas of the brain. Several other, more subtle differences also set the stutterers apart. But "there was not one distinct feature across all stutterers," Foundas says. Rather, each stutterer had an average of four unusual features, while nonstutterers tended to have only one.
The study "very conclusively" shows anatomic differences in the brains of stutterers and nonstutterers, says speech pathologist Roger Ingham of the University of California, Santa Barbara. He says it provides "an important link" in the growing evidence for genetic and physiologic basis of stuttering.