TUESDAY, Aug. 6, 2002 (HealthDayNews) --
Last week's report from German scientists that stuttering is caused by a structural abnormality in the brain probably won't change how the disorder is diagnosed and treated -- at least for now.
However, the study was lauded by speech communications experts, who say the discovery could increase understanding of the speech disorder and may help decide which children will outgrow the stammering without treatment.
Currently, about 3 million Americans stutter, according to the American Speech-Language-Hearing Association, and most of them are children. Most outgrow stuttering, but about 1 percent of adult Americans still have the problem.
Some of them, according to the Stuttering Foundation of America, are famous, including actress Julia Roberts, newsman John Stossel and the late British statesman Winston Churchill.
In the study, reported in The Lancet, researchers from the Universities of Hamburg and Gottingen conducted sophisticated brain scans of 15 adults who stutter and 15 adults with normal speech, and found the tissue structure of a region in the brain's left hemisphere was different in the stuttering patients.
Fiber tracts in the region studied connect brain structures crucial for articulation and speech planning, the researchers say. They also found timing disturbances between areas involved in language preparation and execution in the left hemisphere of the stuttering subjects, and they speculate disruption of the fiber tracts might cause the stuttering problems.
The researchers are not the first to suggest this mechanism underlying stuttering, says Dr. Cornelius Weiller of the University of Hamburg, one of the researchers, "but the first who found evidence on an anatomical basis for that [mechanism]."
In the journal report, Weiller and his co-authors note, "This abnormality probably develops during the period of early language and speech acquisition in which many children experience a transient phase of stuttering."
Almost all children experience a stage of what experts call disfluency between the ages of 2 and 5. Usually these speech problems disappear as the child ages, but not always.
In the stuttering subjects, the right hemisphere areas of the brain involved in language were found to compensate, but the researchers don't think the alternative explanation -- that the right hemisphere overcompensation was the cause of the stuttering -- is valid.
Causes of stuttering have been debated for years, and some experts say they may involve different factors for different people.
The value of the research, the Germans conclude, may be a way to decide why some children stutter only temporarily and others do not outgrow it.
A speech pathology expert praises the study, but has some caveats.
"I think the study is well done," says Lisa Scott Trautman, an assistant professor of communication disorders at Florida State University. "But I think the results should be interpreted with caution, for the reasons they mention." As the researchers note, the study sample was small and they studied only adult subjects.
"They didn't control for previous [speech] therapy experience, " she adds, and that could have affected the findings. She also suggests the right hemisphere overactivation "might be a result of living with the stuttering."
For now, Trautman says, the German findings provide just one more potential piece of the puzzle.
"Any sort of clinical implication is a ways off yet," she adds. However, she says, "having a better understanding of stuttering itself is helpful. It's not going to change the way we treat or diagnose stuttering."
Deciding which children need intervention in the form of speech therapy is a dilemma for doctors and speech pathologists, Trautman says: "What this research may do, in 10 years or so, is help us make that decision at an earlier point."
Weiller says the German team next plans to study children who used to stutter, but then outgrew it.
What To Do
For information on stuttering, see The American Speech-Language-Hearing Association. For a list of famous stutterers, including Winston Churchill, see the Stuttering Foundation of America.
