What Causes Stuttering?

One of the questions I hear most often is, “What causes stuttering?” The answer depends on which kind of stuttering we’re talking about.

When most people hear the word, “stuttering”, developmental stuttering comes to mind, as it is the most common type.

There are also two forms of acquired stuttering. Acquired means that a specific event happens that causes the stuttering, rather than the stuttering developing during childhood. The two forms of acquired stuttering are psychogenic stuttering and neurogenic stuttering.

Developmental stuttering

Developmental stuttering develops while a child is learning speech and language. As speech develops, some children also develop differences in the timing and coordination of speech. For most children, those differences eventually go away. For others, those differences become a natural part of the way they speak throughout their lives. When parents ask what caused their child to begin stuttering, this is usually the kind of stuttering they are asking about.

We do not know exactly why developmental stuttering begins. Like many things that develop during childhood, it is likely influenced by several factors rather than one single cause.

Researchers have learned a great deal and those discoveries give us important clues.

What do we know?

One clue is that developmental stuttering often runs in families. We know there is a genetic component. Research involving identical and fraternal twins also supports the idea that genetics plays a role. At the same time, having a family history of stuttering does not guarantee that someone will stutter. Some people who stutter do not have a known family history at all.

Researchers have also compared the brains of people who stutter with the brains of people who do not stutter. They have found some differences between the two groups, particularly in areas involved in speech timing and coordination. These findings help us better understand what may be happening biologically when stuttering develops.

Psychogenic stuttering

A second type of stuttering is called psychogenic stuttering. Psychogenic stuttering begins in connection with significant psychological trauma or emotional distress. There is usually a clearer connection between something that happened in the person’s life and the onset of the stuttering.

This type of stuttering is not always well understood, and identifying it may require a careful evaluation to rule out neurological causes. A speech-language pathologist may help recognize and treat the speech symptoms, but support often involves a team that includes a mental health professional who can address the underlying trauma or psychological factors.

Neurogenic stuttering

The third type is called neurogenic stuttering. Neurogenic stuttering happens after an injury or change to the brain. It may occur after an event like a stroke or a traumatic brain injury.

Neurogenic stuttering is the one type of stuttering I have experienced myself. I had a frontal concussion at age 24, after a major auto accident. As a result, I have experienced moments of stuttering. For me, stuttering usually shows up as easy part-word, whole word, or whole phrase repetitions. These moments are brief and don’t occur frequently, but when it happens, I usually feel surprised. I find myself thinking, “Oh, wow. Did that just happen?” Those moments have given me a small glimpse into the motor side of stuttering and what it feels like when speech does not come out exactly the way you expected. My experience is still very different from a person who has lived with stuttering throughout their life. I can relate to the physical experience, but I have not experienced the fear, avoidance, or struggle that can sometimes develop around stuttering.

A Quick Summary

Here's a quick visual summary of the types of stuttering, each with a different cause.

What doesn’t cause stuttering?

Even though we do not know everything about why developmental stuttering begins, we know that it is not caused by nervousness, anxiety, poor parenting, low intelligence, laziness, or a lack of effort.

These beliefs can be harmful because they suggest that the person who stutters, or someone around them, has done something wrong. They can also create the impression that stuttering would go away if the person simply relaxed, tried harder, or learned to speak fluently.

Stuttering is not a reflection of intelligence, effort, or communication ability. In fact, many people who stutter are excellent communicators.

One well-known example is comedian Drew Lynch, who developed a stutter after a sports injury as a teenager. He is a very funny comedian and is a great example of a successful communicator who stutters. If you'd like to learn more, I encourage you to visit Drew Lynch's official YouTube channel.

Why understanding the cause matters

Our beliefs about what causes stuttering shape the way we respond to people who stutter. If we believe someone is simply nervous or not trying hard enough, we may respond very differently than if we understand that stuttering reflects differences in how speech is timed and coordinated.

Understanding the cause does not answer every question. There is still a lot to learn about stuttering. But the more we understand, the more likely we are to replace myths with accurate information, and support people who stutter in ways that are genuinely helpful.

Understanding Stuttering Series

This article is part of our Understanding Stuttering series. If you'd like to learn more, these articles build on one another:

• What Is Stuttering?

• Why Does Stuttering Change So Much?

• What Causes Stuttering?

• Are You Stuttering or Struggling?