What causes stuttering? A speech pathology researcher explains the science and the misconceptions around this speech disorder

What comes to mind when you think of someone who stutters? Is that person male or female? Are they weak and nervous, or powerful and heroic? If you have a choice, would you like to marry them, introduce them to your friends or recommend them for a job?

Your attitudes toward people who stutter may depend partly on what you think causes stuttering. If you think that stuttering is due to psychological causes, such as being nervous, research suggests that you are more likely to distance yourself from those who stutter and view them more negatively.

I am a person who stutters and a doctoral candidate in speech, language and hearing sciences. Growing up, I tried my best to hide my stuttering and to pass as fluent.

I avoided sounds and words that I might stutter on. I avoided ordering the dishes I wanted to eat at the school cafeteria to avoid stuttering. I asked my teacher to not call on me in class because I didn’t want to deal with the laughter from my classmates when they heard my stutter. Those experiences motivated me to investigate stuttering so that I can help people who stutter, including myself, to better cope with the condition.

In writing about what the scientific field has to say about stuttering and its biological causes, I hope I can reduce the stigma and misunderstanding surrounding the disorder.

The most recognizable characteristics of developmental stuttering are the repetitions, prolongations and blocks in people’s speech. People who stutter may also experience muscle tension during speech and exhibit secondary behaviors, such as tics and grimaces.

People who stutter often react to their experience of stuttering with anxiety, frustration and embarrassment. In addition, people often anticipate that they may stutter and – as I did – actively avoid stuttering by avoiding sounds or situations. Some may also develop unhelpful thoughts and beliefs about themselves and their ability to communicate with others, such as that they won’t succeed in life or that they cannot talk properly.

The exact cause of stuttering is still unknown. However, it’s widely agreed upon that stuttering is a complex neurodevelopmental disorder.

Neuroimaging studies from both children and adults who stutter point to a malfunction in areas of the brain responsible for timing of movements and skilled motor control – such as speech production – called the cortico-basal ganglia-thalamocortical loop. Yet researchers also know that brain development can be shaped by experience.

Therefore, the anomalies in brain connectivity among adults who stutter could result from their experience of stuttering rather than what contributes to its onset. Ongoing studies looking at differences between children and adults who stutter could help illuminate the core deficits that are associated with the onset of stuttering.

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