The cause of stuttering continues to elude scientists, although a new study may have finally shed some light on why some people struggle to form words, by revealing that a brain region called the Broca’s area receives a reduced blood flow in people who stammer.
Previously, researchers have focused on the mechanics of speech when attempting to uncover the cause of stuttering, working on the assumption that the impediment is caused by problems with the vocal tract or tongue.
However, the new study, published in the journal Human Brain Mapping, found that the issue is very much a cerebral rather than a mechanical one.
Using magnetic resonance imaging (MRI), the study authors measured the blood flow in the brains of 26 stutterers and 36 people who have no difficulty talking fluently. Results showed that those who stutter have a reduced blood flow in the Broca’s area, and that the magnitude of this effect is directly correlated to the severity of their stammering.
The Broca’s area plays a major role in speech production, and has been shown to coordinate the fine movements necessary for talking. It has also been implicated in what scientists call “lexical retrieval”, which refers to the process of getting from a mental concept to a spoken word.
In a statement, study co-author Jay Desai confirmed that “blood flow was inversely correlated to the degree of stuttering – the more severe the stuttering, the less blood flow to this part of the brain.”
And while it is not yet known what causes this disruption to cerebral blood flow, this latest discovery may at least help researchers to devise new treatments that target the parts of the brain responsible for stuttering.