Space & Innovation

A Root Cause of Stuttering Is Being Pinpointed in the Brain

Reduced blood flow to a specific brain region has been identified as a likely cause of stuttering.

For decades and as recently as 1990, many medical professionals believed stuttering, an interruption in the flow of speech, was caused by some malfunction of the vocal tract, throat or tongue. One treatment even called for injecting botox into the tongue.

But as someone who has grappled with stuttering his whole life, Gerald Maguire had a hunch something more was going on - something in the brain.

"It was conjecture, really, that stuttering was a disorder of the mouth, the throat or tongue," said Maguire, chair of psychiatry and neuroscience at UC Riverside in California. "People were just not looking at the brain."

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Now, thanks to advances in brain imaging, more and more research - including Maguire's own - is proving that a dominant factor behind stuttering may indeed lie within the brain.

The latest research, published in the journal Human Brain Mapping, found that blood flow is reduced in the Broca's area - the region in the frontal lobe of the brain linked to speech production - in people who stutter. More severe stuttering is associated with even greater reductions in blood flow to this region.

"Cerebral blood flow is tightly coupled to neural activity, specifically the frequency of firing of neurons," co-author Jay Desai, a neurologist at Children's Hospital Los Angeles explained to Seeker. "Our findings strongly suggest the presence of reduced neural activity in this Broca's region in persons who stutter."

Maguire has identified the same region of the brain as a factor in previous research, as well as deeper regions of the brain, including the basal ganglia region. He explains that in this region, located at the base of the forebrain, a kind of switch influences activity in the Broca's region.

Other researchers, including Anne L. Foundas of Tulane University in New Orleans, are investigating whether specific brain regions that mediate speech, language and motor functions are asymmetric or larger in one hemisphere than the other in the brains of those who stutter.

The findings lend promise for new treatments for the genetically linked condition that affects more than 70 million people worldwide - or one percent of the global population. The hope is that by identifying what regions of the brain are at play, new therapies can be developed that help normalize neural activity related to speech.

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So far no "cure" for stuttering has been found, but behavioral treatment options have proven to help people speak more fluidly. Desai explained that future treatments could range in form.

"Some ways of altering neural activity in localized brain regions such as Broca's area, and thereby increasing blood flow, include the use of time-varying magnetic and electrical fields (e.g. transcranial magnetic stimulation), as well as various behavioral therapies and medications," Desai said in an email.

Maguire, who is also chair of the board of directors of the National Stuttering Association, has been working on a new drug that targets dopamine, a neurotransmitter that helps control the brain's reward and pleasure centers. The drug he and his colleagues are now testing, called ecopipam, targets dopamine receptors in the brain.

"We believe dopamine may be too high in certain areas of the brain," Maguire explained. "Our thought at UCR is that by altering the dopamine levels we can affect brain activity. We're looking now at receptors and modulating the receptors of dopamine in the hope of altering the brain's activity."

Ecopipam has already shown promising results in treating Tourette syndrome, another neurological condition. The drug is currently being tested in an FDA-approved clinical trial. Maguire, himself, is hopeful it may prove effective.

He should know - he's been taking another drug that targets dopamine receptors for his stuttering.

As one could tell by his fluid speech, the therapy works well. And as someone who grew up with the condition - and the stigma it can create during childhood - Maguire appreciates what a difference good therapies can make.

"If we can develop targeted treatments and speech therapy targeting these regions of the brain, we hope to make a big difference in people's lives - particularly in children," he said.

Photo: King George VI suffered throughout life with a stuttering condition. This image is from "The King's Speech," a movie about the king.

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