Reduced blood flow in a part of the brain that's linked to speech may put people at risk for stuttering, a small study suggests.
Abnormal blood flow
There are also signs that the lower the blood flow in regions of the brain tied to speech and language, the more severe the stuttering, the researchers added.
"When other portions of the brain circuit related to speech were also affected according to our blood flow measurements, we saw more severe stuttering in both children and adults," said study first author Dr Jay Desai. He is a clinical neurologist at Children's Hospital, Los Angeles.
Read: More bilingual kids stutter
For the study, the investigators used MRI scans to look at the blood flow in the brains of 26 participants with stuttering and 36 participants without the speech disorder.
The researchers found evidence among those who stuttered of reduced blood flow to the Broca's area of the brain, which sits in the frontal lobe. And the study authors linked more severe stuttering to higher levels of abnormal blood flow in a brain region that handles word processing.
Affects people of all ages
"The more severe the stuttering, the less blood flow to this part of the brain," Desai said in a hospital news release.
The study could not prove cause and effect. But, the authors said they believe stuttering is tied to something going wrong in a neural brain "loop" that's devoted to language.
The study was published online in the journal Human Brain Mapping.
An estimated three million Americans stutter. It occurs most often between the ages of two and six, but stuttering affects people of all ages. Most children outgrow it, but for 25 percent of those affected, stuttering becomes a lifelong disorder, according to the US National Institute on Deafness and Other Communication Disorders.
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