Researchers think they might have found a clue as to what is going on with the 3 million Americans who have long-term stuttering problems. Many children have a brief stuttering phase while they are learning the mechanics of speaking, but it usually fades with time. When it doesn’t, the result is involuntary repetitions of sounds and pauses that could mean lifelong disfluency. These problems are more frequent in men than in women; there is no evidence that stuttering is more or less prevalent in speakers of certain languages, or in people who speak more than one language.
What the researchers found is that MRI scans of the frontal gyrus, the part of the brain responsible for the anatomical mechanics of speech, shows less of a particular type of brain tissue—gray matter, where neural cells are—in children who stutter than in children with typical levels of fluency. This interference with the mechanics is why stuttering is found even in people who only speak sign language. The children who stuttered also had less white matter—axons that link neurons and allow them to communicate—in the corpus callosum, the body that divides the brain into hemispheres. This was the first imaging study to look at the brains of children, rather than adults, who have fluency issues. The reason for the difference is unclear, though there appears to be a genetic influence.
The good news is that, while stuttering can lead to fears around speaking, the social consequences among preschoolers aren’t as dire as one might expect. A study published this past August found more stuttering than had been expected, but also found no evidence of worse outcomes in emotional health or social relationships for stutterers in that age group—perhaps because of the relative commonness of the condition.
None of which, however, means that parents of a child who stutters should forgo treatment for their child. Children who stutter later in higher grades do tend to have anxiety and poor performance, even if they don’t suffer the disdain of peers. While many children who stutter do go on to develop typical levels of fluency, intervention can make an enormous difference to those who otherwise might not.