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Stuttering is a speech disorder characterized by a difficulty in producing the sounds that make up words. As a consequence, people that stutter seem to get "stuck" while pronouncing words, or have difficulty getting words out of the mouth. For this reason, it can take a long time for people with a stutter to get their message across. In severe cases, they may not be able to pronounce some words at all. Although individuals who stutter may develop emotional problems, such as fear of meeting new people or speaking on the telephone, these problems are often a result, rather than cause, of stuttering.



The most common form of stuttering is thought to be developmental, that is, it is occurring in children who are in the process of developing speech and language. This type of stuttering is felt to occur when a child's speech and language abilities are unable to meet his or her verbal demands. Stuttering happens when the child searches for the correct word. Developmental stuttering is usually outgrown.

Another common form of stuttering is neurogenic. In neurogenic stuttering, the brain is unable to adequately coordinate the different components of the speech mechanism. Neurogenic stuttering may also occur following a stroke or other type of brain injury.

Other forms of stuttering are classified as psychogenic. Psychogenic stuttering originates in the mind and may result from mental activity of the brain, such as that which occurs during thought and reasoning. {{#ev:youtube|tEitDTX2ZAo}}

Normal Speech Production

Diagram showing the location of the nasal cavity, palate, tongue, vocal cords, larynx, food channel, and trachea, or windpipe. Source: National Institute on Deafness and Other Communication Disorders, National Institutes of Health.

Speech is normally produced through a series of precisely coordinated muscle movements involving respiration (the breathing mechanism), phonation (the voicing mechanism) and articulation (throat, palate, tongue, lips and teeth). These muscle movements are initiated, coordinated and controlled by the brain. They are monitored through the senses of hearing and touch.

Before speaking, an individual takes a breath and the vocal folds (or vocal cords), which are two bands of muscular tissue located in the voice box directly above the trachea or windpipe, come together. The voice is produced by vibrations of the vocal folds as the air from the lungs passes through them. The sound of the voice is passed through the throat and is directed into the mouth for most speech sounds, or into the nose for nasal sounds such as "m," "n," and "ng." The palate, tongue, jaw and lips move in precise ways to modify the sounds in order to make speech sounds.

Signs and Symptoms

Some common signs of stuttering:

  • Pauses between or within words
  • Repetition of sounds, parts of words, or whole words
  • Having discomfort while talking
  • Frequently using interjections such as "uh" or "um"
  • Using words that are easy to pronounce, such as those with one or two syllables, instead of using more complex words
  • Using incomplete phrases
  • Using explanatory or seemingly unrelated words or phrases when conveying a thought

Some signs of stuttering are not related to speech itself, but rather result from difficulties in speaking. Signs of these secondary behaviors include movements that terminate a speech attempt. This avoidance can take the form of head jerks, finger tapping, or eye blinking.


Scientists suspect that stuttering has numerous causes. Many forms probably have a genetic basis, but the gene or genes that cause stuttering have not been identified. The exact mechanisms underlying stuttering are not understood.

At one time, the major cause of stuttering was thought to be psychogenic. Now, psychogenic stuttering is believed to account for only a minority of stuttering conditions. Psychogenic stuttering occasionally occurs in individuals who have some types of mental illness or individuals who have experienced severe mental stress or anguish.


Stuttering is generally diagnosed by a speech-language pathologist, a professional who is specially trained to test and treat individuals with voice, speech and language disorders. The diagnosis is usually based on the history of the disorder, such as when it was first noticed and under what circumstances, as well as a complete evaluation of speech and language abilities.


There are a variety of treatments available for stuttering. Any of the methods may improve stuttering to some degree, but there is at present no cure for stuttering. Stuttering therapy, however, may help prevent developmental stuttering from becoming a life-long problem. Therefore, a speech evaluation has been recommended for children who stutter for longer than six months, or for those whose stuttering is accompanied by struggle behaviors.

Developmental stuttering is often treated by educating parents about restructuring the child's speaking environment to reduce the episodes of stuttering. Several approaches can be used to limit stuttering in children:

  • A relaxed home environment that provides ample opportunities for the child to speak
  • Setting aside specific times when the child and parent can speak free of distractions.
  • Refraining from criticizing the child's speech, or reacting negatively to a child's problems with speaking.
  • Avoidance of punishment for not speaking correctly.
  • Insisting that a child continually speak the word until it is pronounced correctly
  • Resisting encouraging the child to perform verbally for people
  • Listening attentively to the child when he or she speaks
  • Speaking slowly and in a relaxed manner; children tend to speak like their parents.
  • Waiting for the child to say the intended word without pressuring them.
  • Talking openly to the child about stuttering if he or she brings up the subject.

Many of the currently popular therapy programs for persistent stuttering focus on relearning how to speak or unlearning faulty ways of speaking. The psychological side effects of stuttering that often occur, such as fear of speaking to strangers or in public, are also addressed in most of these programs.

Other forms of therapy utilize interventions such as medications or electronic devices. Medications or drugs which affect brain function often have side effects that make them difficult to use for long-term treatment. Electronic devices which help an individual control fluency may be more of a bother than a help in most speaking situations and are often abandoned by individuals who stutter.

Chances of Developing Stuttering

According to the Canadian Stuttering Association, approximately 1% of adults and 5% of children stutter.[1] Stuttering affects individuals of all ages but occurs most frequently in young children between the ages of two years and six years who are developing language. Boys are four times more likely to stutter than are girls. Most children, however, outgrow their stuttering before they become adults. Almost 80% of children who stutter recover fluency by the age of 16 years. The prognosis is favorable provided that treatment is started early. The outcome is less favorable for individuals who continue to stutter into adulthood. [2]

Clinical Trials

A list of ongoing trials is available at stuttering trials.


Recent discoveries

  • The effectiveness of a device called SpeechEasy in reducing stuttering frequency, and inproving speech rate, and speech naturalness was evaluated. [3]
  • The psychological effects of stuttering in adolescence was evaluated and management strategies discussed. [4]
  • The factors thought to contribute to late (age 12) stuttering were evaluated. [5]
  • The efficacy of parent-child interaction therapy in the treatment of stuttering was evaluated. [6]

Future research

  • A study using positron emission tomography (PET) to examine the role of the chemical messenger dopamine in stuttering. It will measure and compare the number of dopamine receptors and the amount of dopamine released in the brains of stutterers with that of normal volunteers. The results may provide information about how drugs that block dopamine's effect might work to enable fluent speech. [7]
  • A study called "EXPRESS" (Examining Pagoclone for Persistent Developmental Stuttering Study) will determine the effects of pagoclone (an experimental durg used as an anti-anxiety agent) on the symptoms of stuttering persisting into adulthood. [8]


The ancient Greeks believed that stuttering resulted from dryness of the tongue. In the 19th century, stuttering was widely believed to be caused by an anatomic defect in the oral cavity. Surgical procedures, sometimes gruesome, were popular treatments. By the 20th century, stuttering was believed to be a psychogenic disorder and psychological treatment was believed to be the most promising therapy. When psychological treatment did not work, another cause for stuttering was sought. [2]


  1. Canadian Stuttering Association Web site. About the Canadian Stuttering Association
  2. 2.0 2.1 Lawrence M, Barclay DM. Stuttering: a brief review. Am Fam Physician. 1998 May 1;57(9):2175-8. Abstract | Full Text
  3. Armson J, Kiefte M. The effect of SpeechEasy on stuttering frequency, speech rate, and speech naturalness. J Fluency Disord. 2008;33(2):120-34. Epub 2008 May 7. Abstract
  4. Hearne A, Packman A, Onslow M, Quine S. Stuttering and its treatment in adolescence: the perceptions of people who stutter. J Fluency Disord. 2008;33(2):81-98. Epub 2008 Jan 17. Abstract
  5. Howell P, Davis S, Williams R. Late childhood stuttering. J Speech Hear Res. 2008 Jun;51(3):669-87. Abstract | PDF
  6. Millard SK, Nicholas A, Cook FM. Is parent-child interaction therapy effective in reducing stuttering? J Speech Lang Hear Res. 2008 Jun;51(3):636-50. Abstract
  7. Dopamine Function in Developmental Stuttering
  8. EXPRESS: Examining Pagoclone for Persistent Developmental Stuttering Study

External Links

The Canadian Stuttering Association

International Stuttering Association

Stuttering Treatment and Research Trust - START (NZ)

Stuttering Association of Nigeria

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