What Is Stuttering?

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Stuttering, also called childhood-onset fluency disorder or stammering, is a speech disorder that disrupts the fluency of speech (the ability to express yourself). It's estimated that about 5%–10% of kids go through a period of stuttering or disfluent speech during childhood. Approximately 25% of those cases will continue into adulthood.

This article gives an overview of the different types of stuttering, symptoms, causes, treatment options, and coping strategies.

Doctor helping child with a stutter

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Stuttering and stammering are synonymous and are used interchangeably throughout this article.

Types of Stuttering

The two predominant types of stuttering are:

  • Developmental stuttering: The most common type of stuttering begins in early childhood when language skills and speech patterns are developing. This is called childhood-onset fluency disorder.
  • Adult-onset stuttering: If the onset of stuttering starts in adolescence or early adulthood, it's called adult-onset fluency disorder. Typically, this type of stuttering is due to conversion disorder. It may also be caused by stroke or a progressive neurological condition. Certain medications and psychological or emotional trauma can also cause late-onset stuttering.

Stutter Symptoms

Stuttering can cause speech disfluencies such as first-letter repetitions (such as "c-c-c-cat"), whole-word repetitions (such as "and, and, and"), or prolongations (such as "mmmmouse"). Hesitations and long silent pauses between words are also common stutter symptoms.

The severity of stuttering symptoms varies significantly from person to person and depends on ever-changing, real-life circumstances. Some people may stutter in certain situations but speak fluently in others. That said, just because someone who stutters can speak with fluency sometimes doesn't mean they will speak without a stammer all the time.

According to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), stutter symptoms associated with childhood-onset fluency disorder include disruptions in the fluency and timing patterns of speech that are unsuitable for an individual's age or language ability.

More specifically, the DSM-5 diagnostic criteria for childhood-onset fluency disorder require repeated occurrences of one or more of the following seven stutter symptoms:

  1. Audible or silent blocking (pauses in speech)
  2. Broken words (e.g., pauses within a word)
  3. Circumlocutions (overuse of words) that use substitutions to avoid problematic words
  4. Monosyllabic whole-word repetitions ("I-I-I-I see it")
  5. Prolongation of consonants or vowels ("mmmmilk")
  6. Sound and syllable repetitions ("d-d-d-dog")
  7. Excess physical tension when producing words

While less common, secondary stuttering symptoms may also include "struggle behaviors," such as:

  • Facial tics
  • Rapid eye blinks
  • Lip or jaw tremors
  • Head jerks
  • Fist clenching


The exact causes of stuttering are unclear, but there are many theories. Researchers speculate that stuttering is caused by a combination of factors that include genetics, environment, and brain wiring.

Disruptions in the neural networks that support language, speech, and emotional functions during pivotal stages of development play a role in childhood-onset fluency disorder. Neuroimaging research suggests that stuttering severity may be linked to decreased connectivity between the cerebellum (the structure that contains 50% of the brain's neurons) and speech-related areas in the prefrontal cortex.

Unfortunately, there are many misconceptions about stuttering. Contrary to popular belief, nervousness and shyness don't cause stuttering. Although stressful situations may worsen stuttering, onlookers shouldn't assume that people who stutter are inherently more nervous, anxious, or shy than someone who speaks with fluency.

Although there is a correlation between social anxiety disorder (SAD) and stuttering, it's possible that stuttering causes higher levels of anxiety and not vice versa. Accumulating evidence suggests that social phobias or anxiety probably aren't the root cause of stuttering. Still, the high prevalence of SAD among stutterers is still poorly understood and requires more research.


In 2013, the official DSM-5 diagnostic term used for people who stammer was changed from "stuttering" to "childhood-onset fluency disorder."

The diagnostic criteria also changed. Most notably, commonly used interjections such as "ums," "ahs," and saying "you know" were removed from the diagnostic criteria, while social anxiety and avoidance behaviors were added.

A stuttering diagnosis is usually made by a speech-language pathologist or another healthcare provider trained to evaluate communication disorders related to speech.

There isn't a single, one-time test used to diagnose stuttering. Rather, the frequency of speech disfluency is assessed over a period of time and in different situations.


Although there isn't a cure or magic bullet for stuttering, there are helpful treatments. The nature of stuttering treatment will vary depending on someone's age, communication goals, and other factors.

The most common treatments for stuttering involve speech therapy and cognitive behavioral therapy (CBT).

Clinical psychologists at the University of California at Los Angeles (UCLA) encourage people who stutter to accept the condition and to stutter openly. This approach is called "acceptance therapy." Accepting this speech disorder reduces fear and shame among people who stutter, which leads to less stuttering.


Most kids with childhood-onset fluency disorder outgrow stuttering as they get older. It's estimated that 75%–80% of all children who undergo speech therapy will stop stuttering within one to two years.

Up to 25% of cases of childhood stuttering will continue into adulthood.


Numerous nonprofit organizations offer support and coping strategies for people of all ages in the greater stuttering community. Some of these include:


Roughly 5%–10% of all children go through a period of stuttering, or childhood-onset fluency disorder. Most kids outgrow this speech disorder, but it can continue into adulthood. Symptoms include word prolongations, repetitions, pauses, broken words, and more.

The causes of stuttering are not clearly understood, but evidence suggests that atypical brain wiring—not underlying anxiety—is the root cause. Although there isn't a cure for stuttering, speech therapy and cognitive behavioral therapy can help people who stutter speak with more fluency.

A Word From Verywell

Stuttering is very common and nothing to feel embarrassed about. Globally, over 70 million people stutter. Even President Joe Biden stuttered as a child and still does from time to time. Reducing the stigma around stuttering can help those who stutter overcome or improve their condition.

14 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. National Institute on Deafness and Other Communication Disorders. Stuttering.

  2. National Health Service. Stammering overview.

  3. Mendez MF. Non-neurogenic language disorders: a preliminary classificationPsychosomatics. 2018;59(1):28-35. doi:10.1016/j.psym.2017.08.006

  4. Gerlach H, Subramanian A, Wislar E. Stuttering and its invisibility: why does my classmate only stutter sometimes?Front Young Minds. 2020;7:153. doi:10.3389/frym.2019.00153

  5. Maguire GA, Yeh CY, Ito BS. Overview of the diagnosis and treatment of stutteringJournal of Experimental & Clinical Medicine. 2012;4(2):92-97. doi:10.1016/j.jecm.2012.02.001

  6. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. Fifth Edition. American Psychiatric Association; 2013. doi:10.1176/appi.books.9780890425596

  7. Sander RW, Osborne CA. Stuttering: understanding and treating a common disability. Am Fam Physician. 2019;100(9):556-560.

  8. Smith A, Weber C. How stuttering develops: the multifactorial dynamic pathways theoryJ Speech Lang Hear Res. 2017;60(9):2483-2505. doi:10.1044/2017_JSLHR-S-16-0343

  9. Sitek KR, Cai S, Beal DS, Perkell JS, Guenther FH, Ghosh SS. Decreased cerebellar-orbitofrontal connectivity correlates with stuttering severity: whole-brain functional and structural connectivity associations with persistent developmental stutteringFront Hum Neurosci. 2016;10:190. doi:10.3389/fnhum.2016.00190

  10. Stuttering Foundation. Five myths about stuttering.

  11. Ahmed, HH, Mohammed, HO. Social anxiety disorders among stutterers: effects of different variantsEgypt J Otolaryngol. 2018;34, 155–164 doi:10.4103/ejo.ejo_72_17

  12. American Psychological Association. A new name for stuttering in DSM-5.

  13. UCLA Health. Joe Biden’s presidential run put spotlight on stuttering.

  14. Stuttering Foundation. Prevalence.

By Christopher Bergland
Christopher Bergland is a retired ultra-endurance athlete turned medical writer and science reporter.