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.

In “The King’s Speech,” a recent movie set in pre-World War II England, soon-to-be King George VI has to conquer a stammer (Americans call it a stutter) that has hindered him since childhood and makes public speaking an agony. With the help of a speech therapist, the king learns how to control his stutter enough to get through a speech. But King George never completely defeated his stutter. Although he managed to overcome the characteristic repetition of sounds at the beginnings of words, in old films you can still see him pausing, grimacing, gathering his courage and moving on as best he can.

More than 50 years later, therapies for those who stutter aren’t that different from the king’s. Many, like King George's, focus on learning ways to minimize the impact of the disorder. They involve learning to speak more slowly, regulating breathing, and gradually progressing from single-syllable responses to longer words and more complex sentences.

Stuttering affects more than 3 million people in America and another 60 million worldwide. Approximately 75% to 85% of those who stutter in childhood will outgrow it when they become adults. However, there is currently no way to know who will stop and who will continue. Boys are more than twice as likely as girls to stutter, a difference that increases even more in adulthood, when men are 3 to 4 times more likely to stutter than women.

People have recognized stuttering as a speech disorder for thousands of years. They’ve speculated about what causes it for just as long. In King George’s time, it was thought to stem from childhood emotional trauma or an unhealthy attachment to a parent, usually the mother. Today, some people still mistakenly think that stuttering is caused by psychological or social problems, or nervousness and anxiety.

That’s beginning to change because of a recent discovery by a team of researchers led by NIH scientists. They identified changes in 3 different genes that appear to play a role in stuttering. The researchers propose that part of the brain dedicated to fluency of speech may be uniquely sensitive to problems caused by defects in these genes. Further research could provide new insights into what causes stuttering. Eventually, this work may suggest ways to correct the problem.

Researchers hope that one day stuttering can be treated as a biological disorder with a medical cure, not a character weakness. In the meantime, if you or your child stutters, a variety of treatments are available. Talk to a speech-language pathologist—a health professional trained to test and treat children with voice, speech and language problems—about the options.

If Your Child Stutters

Many children stutter as toddlers and pre-schoolers but grow out of it. Bring your child in for evaluation if:

• stuttering has continued for 6 months or longer
• your child has other problems with speech or language
• your child has strong fears or concerns about stuttering
• there is a family history of stuttering

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.

Stuttering is a complex speech condition that can cause a person to get stuck trying to say certain sounds, syllables, or words.

People who stutter know exactly what they want to say, but they have trouble producing a normal flow of speech. Sometimes they repeat certain sounds. They may also experience an interruption, called a block, when they can’t say the word or sound they want to use.

How many people stutter?

About 3 million Americans stutter, and stuttering affects four times as many males as females.

When does it happen?

Developmental stuttering is most common. It occurs in children between the ages of 2 and 6, as they develop their language skills. It can last from a few weeks to many years – even into adulthood. to several years. About 75% of children recover from stuttering.

Neurogenic stuttering is more rare and can be caused by a stroke or serious head or brain injury.

What causes stuttering?

The exact cause of stuttering is not well understood, but genetic factors are clearly involved. About 60% of people who stutter also have a family member who stutters. New research indicates there may be a genetic link to the condition.

Researchers with the National Institute on Deafness and Other Communication Disorders (NIDCD) have identified mutations in four different genes that are linked to stuttering that persists throughout life.

How is it diagnosed?

Stuttering is usually diagnosed by a speech-language pathologist, a health care professional who tests and treats individuals with voice, speech, and language disorders.

How is it treated?

There currently is no cure for stuttering. Speech-language pathologists can use a variety of treatments specialized for children, teens, and adults.

Antidepressants and antianxiety drugs are sometimes prescribed for those who stutter. But a study funded by NIDCD found drug therapy largely ineffective in controlling stuttering long term.

Electronic devices that fit into the ear canal and slightly alter the sound of a person’s voice can be used on a short-term basis. In addition, many people find success through a combination of speech therapy and support groups.

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 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.

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.

Stuttering affects more people than you might think. Roughly 3 million Americans have this speech disorder that makes speaking smoothly difficult. Scientists are learning about what causes people to stutter, and genes tell a big part of the story.

“People with stuttering know exactly what they want to say. They’re just unable to say it at the rate they would like,” says Dr. Dennis Drayna, an NIH expert on the genetics of communication disorders.

Stuttering often involves speech sounds that are repeated or held for too long—often when starting words or sentences. It affects about 1 in 20 children. Most will outgrow the disorder on their own or with the help of a professional called a speech-language pathologist.

“However, about 20–25% of children who stutter will continue into adulthood,” says Drayna. This condition is known as persistent developmental stuttering. Overall, about 1% of adults stutter, and it’s much more common in men than women.

For those who stutter, communicating with others can be difficult. It can cause anxiety about speaking and lead them to avoid talking. This, in turn, can affect relationships, self-esteem, and quality of life.

It’s common for people who stutter to be able to speak without stuttering when in a low-stress environment. They may have no problem speaking fluently with a pet or baby, for example. Singing or speaking together in a group can also lessen stuttering. But stuttering often gets worse if they’re feeling tired or anxious.

Researchers are still working to fully understand what causes stuttering. But they do know that it often runs in families. “It’s 15 times more likely that a sibling of a person who stutters will stutter than a random person in the population,” explains Drayna.

By studying families with multiple people who stutter, Drayna has identified several genes that can cause stuttering. Mutations in these genes have now been found in people around the world who stutter. These studies suggest that genes likely play a role for many people who stutter.

All the genes identified so far are involved in a process inside the cell called intracellular trafficking. This process helps direct things in the cell to their proper locations. Problems with intracellular trafficking have recently been recognized in other neurological disorders, like Parkinson’s and Alzheimer’s disease. But more research is needed to understand how it impacts speech and stuttering.

Scientists are also using brain imaging scans to better understand brain activity in people who stutter. This may help show why some children outgrow stuttering and hopefully lead to better treatments one day.

For now, treatment for stuttering involves therapy with a speech-language pathologist. Many of the current therapies aim to make speech smoother. Some work to change the thoughts that can bring on or worsen stuttering. Electronic devices are also available to help those who stutter manage their speech.

While stuttering can be an obstacle, there are many resources to help overcome it.

Does Your Child Stutter?

• Be patient and focus on what he or she is saying.
• Listen attentively when your child speaks and wait for him or her to say the intended word. Try not to finish sentences or fill in words.
• Avoid telling your child to “relax” or “slow down.”
• Speak at a relaxed pace with your child and pause often. This can help reduce time pressures the child may be experiencing.
• Set aside some time each day to talk with your child when he or she has your undivided attention.
• Contact a speech pathologist if stuttering lasts over six months.

Joe Lukong had a simple question. The answer he got would change his life.

What Joe wanted to know was, why did he and so many members of his large, extended west African family all stutter? Siblings, aunts, uncles, nephews, cousins: the list went on and on. "Is it possible there could be a genetic link?" he wondered.

As it turned out, there definitely was a link.

The genetic information gathered from Joe’s family allowed NIH researchers to discover another gene linked to stuttering.

Searching for answers

It was 2002, when Joe, then 37, was living in a small rural town in the African country of Cameroon.

He wanted to find out more about his stuttering condition—and find answers for his family. So he decided to participate in an online research symposium where stuttering experts offered to answer people’s questions about the disorder.

When one of the experts saw Joe’s question about his family, they forwarded it to Dennis Drayna, Ph.D., at NIH’s National Institute on Deafness and Other Communication Disorders.

The fourth gene

Dr. Drayna, who was studying the genetics of stuttering, quickly realized that Joe’s huge family could be critical to discovering more genes that could be causing the disorder.

Shortly after, Dr. Drayna and his team traveled to Cameroon. There they took blood samples from more than 150 people, including 50 in Joe’s family who stuttered.

The Lukong family, says Dr. Drayna now, "allowed us to find the fourth gene" linked to stuttering.

Participating in the research had a huge effect on Joe's life too.

Getting help and confidence

It helped him understand stuttering better. It also gave him access to free speech therapy and the confidence to help others who stutter.

"You have to understand, I grew up in a small rural town," Joe says. "In our school, teachers were not sure how to deal with people with speech problems. They would laugh at them and then the students would follow."

"The people who really matter will care what you have to say, not how you say it."- Joe Lukong

As for speech therapists, there were only a few in the entire country and only in the bigger cities.

Joe said he tried to hide his stuttering "because I feared people would have a negative impression of me."

But after the NIDCD research, he helped organize a stuttering conference that helped more than 100 people in Cameroon get speech therapy.

"It helped me realize I wasn’t alone. It helped me let go of my fear of stuttering," he says.

Joe, his wife, and son now live in Minnesota, where he works with people with mental disabilities.

His advice to those who stutter: "Don’t let it keep you from achieving your goals. The people who really matter will care what you have to say, not how you say it."

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.

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 speech-language 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 speech-language 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.

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 interruptng 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 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. Self-help groups provide a way for people who stutter to find resources and support as they face the challenges of stuttering.

Although there is currently no cure for stuttering, there are treatments that can be customized to a child’s age and other factors.

Seeking early treatment is important. It may prevent developmental stuttering (when a child is young) from becoming a lifelong problem. Health professionals generally recommend that a child be evaluated if he or she has stuttered for three to six months. They also recommend an evaluation if there is a family history of stuttering or related communication disorders.

Treatment often involves teaching parents ways to support their child as they develop their language skills.

Parents are often encouraged to:

• Listen attentively when the child speaks. Be patient. Try not to interrupt or finish a child’s sentences. Focus on the content of the message rather than how it is said.
• Speak in a slightly slowed and relaxed manner. This can help reduce the time pressure the child may be experiencing.
• Provide a relaxed home environment that allows many opportunities for the child to speak. This includes one-on-one time with a parent.
• Be less demanding on the child to speak in a certain way or to perform verbally for people. This is especially important if such pressure upsets the child or causes them more difficulty in speaking.

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.

What is stuttering?

Stuttering is a speech disorder. It involves interruptions in the flow of speech. These interruptions are called disfluencies. They may involve:

• Repeating sounds, syllables, or words
• Stretching out a sound
• Suddenly stopping in the middle of a syllable or word

Sometimes, along with the stuttering, there may be nodding, rapid blinking, or trembling lips. The stuttering may be worse when you are stressed, excited, or tired.

Stuttering can be frustrating, because you know exactly what you want to say, but you have trouble saying it. It can make it difficult to communicate with people. This can cause problems with school, work, and relationships.

What causes stuttering?

There are two main types of stuttering, and they have different causes:

• Developmental stuttering is the more common type. It starts in young children while they are still learning speech and language skills. Many children stutter when they first start talking. Most of them will outgrow it. But some continue to stutter, and the exact cause is unknown. There are differences in the brains of people who continue to stutter. Genetics may also play a role, since this type of stuttering can run in families.
• Neurogenic stuttering can happen after someone has a stroke, head trauma, or other type of brain injury. Because of the injury, the brain has trouble coordinating the different parts of the brain involved in speech.

Who is at risk for stuttering?

Stuttering can affect anyone, but it is much more common in boys than girls. Younger children are most likely to stutter. About 75% of children who stutter will get better. For the rest, stuttering can continue their whole lives.

How is stuttering diagnosed?

Stuttering is usually diagnosed by a speech-language pathologist. This is a health professional who is trained to test and treat people with voice, speech, and language disorders. If you or your child stutters, your regular health care provider may give you a referral to a speech-language pathologist. Or in some cases, a child's teacher may make a referral.

To make a diagnosis, the speech-language pathologist will:

• Look at the case history, such as when the stuttering was first noticed, how often it happens, and in what situations it happens
• Listen to you or your child speak and analyze the stuttering
• Evaluate you or your child's speech and language abilities, including the ability to understand and use language
• Ask about the impact of stuttering on you or your child's life
• Ask whether stuttering runs in the family
• For a child, consider how likely it is that he or she will outgrow it

What are the treatments for stuttering?

There are different treatments that can help with stuttering. Some of these may help one person but not another. You need to work with the speech-language pathologist to figure out the best plan for you or your child.

The plan should take into account how long the stuttering has been going on and whether there are any other speech or language problems. For a child, the plan should also take into account your child's age and whether he or she is likely to outgrow the stuttering.

Younger children may not need therapy right away. Their parents and teachers can learn strategies to help the child practice speaking. That can help some children. As a parent, it's important to be calm and relaxed when your child is speaking. If your child feels pressured, it can make it harder for them to talk. The speech-language pathologist will probably want to evaluate your child regularly, to see whether treatment is needed.

Speech therapy can help children and adults minimize stuttering. Some techniques include:

• Speaking more slowly
• Controlling breathing
• Gradually working up from single-syllable responses to longer words and more complex sentences

For adults, self-help groups can help you find resources and support as you face the challenges of stuttering.

There are electronic devices to help with fluency, but more research is needed to see whether they really help over the long term. Some people have tried medicines that usually treat other health problems such as epilepsy, anxiety, or depression. But these medicines are not approved for stuttering, and they often have side effects.