What is it?
Stuttering is a speech disorder. It is characterized by an involuntary repetition of syllables or words, and involuntary and abnormal hesitation and periods of silence before being able to speak. People who stutter in front of other people are often able to speak fluently to pets, little children, and themselves.
About 1% of the world’s population suffer from stuttering. It is more common in men than in women. It’s severity varies a lot, with some cases being almost unnoticeable, while others seriously affect the stutterer’s ability to communicate and cause significant mental distress. Stuttering is sometimes thought to be associated with stupidity and brought about by social anxiety, but in reality, stutterers are generally more intelligent than average, and while mental problems such as social anxiety are associated with stuttering, it is often the stuttering that gives rise to the anxiety, not vice versa.
What causes it?
A link has been found between mutations in three genes, and relatives of stutterers are more likely to stutter themselves, which suggests that there is a hereditary component to the disorder.
Repetition is comforting. Especially children, when facing stress, sometimes acquire the habit of repeating a certain movement a sound – this is called a tic. It has been suggested that stuttering is a complex tic. This would also explain why it is so much more common in men than in women – men have evolved to be hunters and fighters, which is why their bodies interpret situations as stressful more readily than women’s.
What happens during it?
A very precise and controlled sequence of activation in different areas of the brain is necessary for normal speech. Stuttering is thought to be caused by disturbances in how the activation of neural circuits relates to the activation of other ones. Neural imaging has shown that the brains of people who stutter are activated in different ways than the brains of those who don’t.
Normally before speaking, a brain area used for articulation programming is activated before the activation of the motor area producing the actual sound. This relationship has been found to be reversed in stuttering people – the motor area is activated before the articulation area. This, understandably, leads to problems, as one area of the brain is told to say something before it actually knows what to say.
There is also plenty of evidence supporting the proposition that in stuttering, the right hemisphere, associated with feelings, interferes with the speech production of the left hemisphere.The role of right hemisphere activation during speech has been found to be much greater in stuttering people, although it’s not clear why this leads to the stuttering itself.
How can it be treated?
While there is no cure for stuttering, speech therapy can improve the sufferer’s speech so much, that most people would not notice anything strange in the way they talk. It is often also necessary to address the psychological problems the stutterer may have acquired as a consequence of their disorder – these could include things like social anxiety and a very negative self-image.
“Stuttering: a dynamic motor control disorder” by Christy L. Ludlow and Torrey Loucks,