NIDCD...Improving the lives of people with communication disorders

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES ∙ National Institutes of Health

NIDCD Fact Sheet | Voice, Speech, and Language

Stuttering 

What is stuttering?

Stuttering is a speech disorder characterized by repetition 

of sounds, syllables, or words; prolongation of sounds; 

and interruptions in speech known as blocks. An 

individual who stutters exactly knows what he or she 

would like to say but has trouble producing a normal flow 

of speech. These speech disruptions may be accompanied 

by struggle behaviors, such as rapid eye blinks or 

tremors of the lips. Stuttering can make it difficult to 

communicate with other people, which often affects a 

person’s quality of life and interpersonal relationships. 

Stuttering can also negatively influence job performance 

and opportunities, and treatment can come at a high 

financial cost. 

Symptoms of stuttering can vary significantly throughout 

a person’s day. In general, speaking before a group or 

talking on the telephone may make a person’s stuttering 

more severe, while singing, reading, or speaking in unison 

may temporarily reduce stuttering.

Stuttering is sometimes referred to as stammering and by 

a broader term, disfluent speech.

Who stutters?

Roughly 3 million Americans stutter. Stuttering affects 

people of all ages. It occurs most often in children 

between the ages of 2 and 6 as they are developing 

their language skills. Approximately 5 to 10 percent 

of all children will stutter for some period in their life, 

lasting from a few weeks to several years. Boys are 2 to 

3 times as likely to stutter as girls and as they get older 

this gender difference increases; the number of boys 

who continue to stutter is three to four times larger than 

the number of girls. Most children outgrow stuttering. 

Approximately 75 percent of children recover from 

stuttering. For the remaining 25 percent who continue to 

stutter, stuttering can persist as a lifelong communication 

disorder.

How is speech normally produced?

We make speech sounds through a series of precisely 

coordinated muscle movements involving breathing, 

phonation (voice production), and articulation (movement 

of the throat, palate, tongue, and lips). Muscle 

movements are controlled by the brain and monitored 

through our senses of hearing and touch.

What are the causes and types of 

stuttering?

The precise mechanisms that cause stuttering are not 

understood. Stuttering is commonly grouped into two 

types termed developmental and neurogenic.

} Developmental stuttering

Developmental stuttering occurs in young children while 

they are still learning speech and language skills. It is 

the most common form of stuttering. Some scientists 

and clinicians believe that developmental stuttering 

occurs when children’s speech and language abilities 

are unable to meet the child’s verbal demands. Most 

scientists and clinicians believe that developmental 

stuttering stems from complex interactions of multiple 
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factors. Recent brain imaging studies have shown 

consistent differences in those who stutter compared 

to nonstuttering peers. Developmental stuttering may 

also run in families and research has shown that genetic 

factors contribute to this type of stuttering. Starting in 

2010, researchers at the National Institute on Deafness 

and Other Communication Disorders (NIDCD) have 

identified four different genes in which mutations are 

associated with stuttering. More information on the 

genetics of stuttering can be found in the research 

section of this fact sheet.

} Neurogenic stuttering

Neurogenic stuttering may occur after a stroke, head 

trauma, or other type of brain injury. With neurogenic 

stuttering, the brain has difficulty coordinating the 

different brain regions involved in speaking, resulting in 

problems in production of clear, fluent speech. 

At one time, all stuttering was believed to be 

psychogenic, caused by emotional trauma, but today we 

know that psychogenic stuttering is rare.

How is stuttering diagnosed?

Stuttering is usually diagnosed by a speech-language 

pathologist, a health professional who is trained to test 

and treat individuals with voice, speech, and language 

disorders. The speech-language pathologist will consider 

a variety of factors, including the child’s case history 

(such as when the stuttering was first noticed and under 

what circumstances), an analysis of the child’s stuttering 

behaviors, and an evaluation of the child’s speech and 

language abilities and the impact of stuttering on his or 

her life.

When evaluating a young child for stuttering, a speechlanguage pathologist will try to determine if the child 

is likely to continue his or her stuttering behavior or 

outgrow it. To determine this difference, the speechlanguage pathologist will consider such factors as the 

family’s history of stuttering, whether the child’s stuttering 

has lasted 6 months or longer, and whether the child 

exhibits other speech or language problems.

How is stuttering treated?

Although there is currently no cure for stuttering, 

there are a variety of treatments available. The nature 

of the treatment will differ, based upon a person’s 

age, communication goals, and other factors. If you 

or your child stutters, it is important to work with a 

speech-language pathologist to determine the best 

treatment options.

Therapy for children

For very young children, early treatment may prevent 

developmental stuttering from becoming a lifelong 

problem. Certain strategies can help children learn to 

improve their speech fluency while developing positive 

attitudes toward communication. Health professionals 

generally recommend that a child be evaluated if he or 

she has stuttered for 3 to 6 months, exhibits struggle 

behaviors associated with stuttering, or has a family 

history of stuttering or related communication disorders. 

Some researchers recommend that a child be evaluated 

every 3 months to determine if the stuttering is increasing 

or decreasing. Treatment often involves teaching parents 

about ways to support their child’s production of fluent 

speech. Parents may be encouraged to:

} Provide a relaxed home environment that allows many 

opportunities for the child to speak. This includes 

setting aside time to talk to one another, especially 

when the child is excited and has a lot to say. 

} Listen attentively when the child speaks and focus on 

the content of the message, rather than responding to 

how it is said or interrupting the child. 

} Speak in a slightly slowed and relaxed manner. This 

can help reduce time pressures the child may be 

experiencing. 

} Listen attentively when the child speaks and wait for 

him or her to say the intended word. Don’t try to 

complete the child’s sentences. Also, help the child learn 

that a person can communicate successfully even when 

stuttering occurs. 

} Talk openly and honestly to the child about stuttering if 

he or she brings up the subject. Let the child know that 

it is okay for some disruptions to occur. 

Stuttering therapy

Many of the current therapies for teens and adults who 

stutter focus on helping them learn ways to minimize 

stuttering when they speak, such as by speaking more 

slowly, regulating their breathing, or gradually progressing 
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from single-syllable responses to longer words and more 

complex sentences. Most of these therapies also help 

address the anxiety a person who stutters may feel in 

certain speaking situations.

Drug therapy

The U.S. Food and Drug Administration has not approved 

any drug for the treatment of stuttering. However, some 

drugs that are approved to treat other health problems—

such as epilepsy, anxiety, or depression—have been used 

to treat stuttering. These drugs often have side effects 

that make them difficult to use over a long period of time. 

Electronic devices

Some people who stutter use electronic devices to help 

control fluency. For example, one type of device fits into 

the ear canal, much like a hearing aid, and digitally replays 

a slightly altered version of the wearer’s voice into the ear 

so that it sounds as if he or she is speaking in unison with 

another person. In some people, electronic devices may 

help improve fluency in a relatively short period of time. 

Additional research is needed to determine how long such 

effects may last and whether people are able to easily use 

and benefit from these devices in real-world situations. 

For these reasons, researchers are continuing to study the 

long-term effectiveness of these devices.

Self-help groups

Many people find that they achieve their greatest success 

through a combination of self-study and therapy. Selfhelp groups provide a way for people who stutter to 

find resources and support as they face the challenges 

of stuttering.

What research is being conducted 

on stuttering?

Researchers around the world are exploring ways 

to improve the early identification and treatment of 

stuttering and to identify its causes. For example, 

scientists have been working to identify the possible 

genes responsible for stuttering that tend to run in 

families. NIDCD scientists have now identified variants in 

four such genes that account for some cases of stuttering 

in many populations around the world, including the 

United States and Europe. All of these genes encode 

proteins that direct traffic within cells, ensuring that 

various cell components get to their proper location 

within the cell. Such deficits in cellular trafficking are a 

newly recognized cause of many neurological disorders. 

Researchers are now studying how this defect in cellular 

trafficking leads to specific deficits in speech fluency.

Researchers are also working to help speech-language 

pathologists determine which children are most likely to 

outgrow their stuttering and which children are at risk 

for continuing to stutter into adulthood. In addition, 

researchers are examining ways to identify groups of 

individuals who exhibit similar stuttering patterns and 

behaviors that may be associated with a common cause.

Scientists are using brain imaging tools such as PET 

(positron emission tomography) and functional MRI 

(magnetic resonance imaging) scans to investigate brain 

activity in people who stutter. NIDCD-funded researchers 

are also using brain imaging to examine brain structure 

and functional changes that occur during childhood that 

differentiate children who continue to stutter from those 

who recover from stuttering. Brain imaging may be used 

in the future as a way to help treat people who stutter. 

Researchers are studying whether volunteer patients 

who stutter can learn to recognize, with the help of a 

computer program, specific speech patterns that are 

linked to stuttering and to avoid using those patterns 

when speaking.
Where can I find additional 

information about stuttering? 

The NIDCD maintains a directory of organizations that 

provide information on the normal and disordered 

processes of hearing, balance, taste, smell, voice, 

speech, and language. Visit the NIDCD website at 

http://www.nidcd.nih.gov to search the directory. 

Use the following keywords to help you find 

organizations that can answer questions and provide 

information on stuttering:

} Stuttering 

} Speech-language pathologists 

} Physician/practitioner referrals 

Visit the NIDCD website at http://www.nidcd.nih.gov

to read, print, or download publications.

Stuttering

NIH Pub. No. 97-4232 

February 2016 

For more information, additional addresses and phone 

numbers, or a printed list of organizations, contact us at:

NIDCD Information Clearinghouse

1 Communication Avenue 

Bethesda, MD 20892-3456 

Toll-free Voice: (800) 241-1044 

Toll-free TTY: (800) 241-1055 

Fax: (301) 770-8977 

Email: nidcdinfo@nidcd.nih.gov

http://www.nidcd.nih.gov

 Follow the NIDCD on Twitter at @NIDCD

The NIDCD supports and conducts research and 

research training on the normal and disordered 

processes of hearing, balance, taste, smell, voice, 

speech, and language and provides health information, 

based upon scientific discovery, to the public.

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