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Stutterers May Have Brain Differences

Irregularities found in language and speech areas

MONDAY, July 23, 2001 (HealthDayNews) -- People who stutter are more likely to have anatomical differences in the parts of the brain responsible for speech and language, says new research.

It's the first evidence that physical irregularities may predispose some people to stutter. The findings appear in the July 24 issue of the journal Neurology.

Stuttering, sometimes called stammering, is a speech disorder that affects an estimated 3 million Americans. The normal flow of speech is disrupted by the inability to start a word or by repetition or prolongation of speech sounds. When trying to speak fluently, stutterers sometimes develop behaviors such as blinking eyes, or tremors in their lips or jaws.

Stuttering most frequently affects children ages 2 to 6. Boys are three times more likely to stutter than girls, but children generally outgrow the condition. Only about 1 percent of adults have the disorder. Treatments include a variety of behavioral therapies, sometimes using electronic devices, or medications.

The latest study, led by neurologist Dr. L. Anne Foundas of the Tulane University Health Science Center in New Orleans, used volumetric magnetic resonance imaging (MRI) to compare the brains of 16 people with a chronic developmental stutter with the brains of 16 people without a stutter.

Foundas says her study was the first to use the imaging technique, which she describes as opening a window into the living brain, to examine stuttering, although it has been used for dyslexia research.

The researchers, concentrating on several areas in the frontal lobe and temporoparietal region critical to speech and language, found significant differences in the stutterers.

In the frontal lobe, Foundas found that two regions called the pars triangularis and the pars opercularis were larger in stutterers. In the temporal region, a structure called the planum temporale was larger overall, and the left side was closer to being symmetrical with the right side. Normally, the left planum temporale is up to three times the size of its right brain counterpart. "That was the area where we found the most difference in size between the two groups," says Foundas.

"What's particularly interesting is that this area is important in auditory processing," says Foundas. "It suggests that there may be some difference in auditory processing or in those neural systems that are interconnected with other parts of the brain."

The researchers also found extra bumps and crevices in several language-related areas of the stutterers' brains.

"We can only speculate about what the mechanism is, but the fact that we found this difference, and it was so significant, provides strong evidence that it may be important. It may be that it increases vulnerability [to stuttering]," says Foundas.

However, she says this doesn't mean people who stutter are abnormal in a negative way.

"Having atypical features does not necessarily equate with [having] a deficit, Oftentimes, individuals with developmental reading disorders are exceptional in terms of visual-spatial abilities," she says.

And having some of these irregularities doesn't mean someone will be a stutterer, says Foundas. Emotional factors may exacerbate or perpetuate stuttering in those with a biological basis for the condition, she says.

Lisa Scott Trautman, an assistant professor of communicative disorders at Wichita State University in Kansas, says, "There does seem to be good evidence that the brains of adults who stutter are functioning a little bit differently than adults who don't stutter."

"This brain research is just so exciting because it's the first time that we've ever been able to show that something different is going down. We're just not quite sure yet what it all means," says Trautman.

"The potential clinical benefits may be earlier diagnosis or more definitive diagnosis," says Trautman. Identifying stutterers whose condition has specific characteristics "may help us … match treatments to them more appropriately," says Trautman.

Foundas says, "This is our first look. We hope to pursue this in larger groups of people who stutter, and also in children who stutter," with the hope of developing new treatments for stutterers.

What To Do: The Stuttering Foundation of America offers advice on how to react when speaking with someone who stutters. You can also learn what happens during stuttering from this online book, Stuttering: Science, Therapy & Practice, or find more general information from the National Institute on Deafness and Other Communication Disorders.

SOURCES: Interviews with Anne L. Foundas, M.D., associate professor, Department of Psychiatry and Neurology, Tulane University Health Science Center, New Orleans; Lisa Scott Trautman, Ph.D., assistant professor, Department of Communicative Disorders and Sciences, Wichita State University, Wichita, Kan.; July 24, 2001, Neurology
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