Stuttering
Stuttering, also known as stammering, is a speech disorder characterized externally by involuntary repetitions and prolongations of sounds, syllables, words, or phrases as well as involuntary silent pauses called blocks in which the person who stutters is unable to produce sounds. Almost 80 million people worldwide stutter, about 1% of the world's population, with a prevalence among males at least twice that of females. Persistent stuttering into adulthood often leads to outcomes detrimental to overall mental health, such as social isolation and suicidal thoughts.
Stuttering is not connected to the physical ability to produce phonemes. It is also unconnected to the structuring of thoughts into coherent sentences inside sufferers' brains, meaning that people with a stutter know precisely what they are trying to say. Stuttering is purely a neurological disconnect between intent and outcome during the task of expressing each individual sound. While there are rarer neurogenic and psychogenic variants, the typical etiology, development, and presentation is that of idiopathic stuttering in childhood that then becomes persistent into adulthood.
Acute nervousness and stress do not cause stuttering but may trigger increased stuttering in people who have the disorder. There is a significant correlation between anxiety, particularly social anxiety, and stuttering, but stuttering is a distinct, engrained neurobiological phenomenon and thus only exacerbated, not caused, by anxiety. Anxiety consistently worsens stuttering symptoms in acute settings in those with comorbid anxiety disorders.
Living with a stutter can create chronic stress that harms the body over time. However, stress itself does not cause people to develop a stutter.
Characteristics
Audible disfluencies
Common stuttering behaviors are observable signs of speech disfluencies, for example: repeating sounds, syllables, words or phrases, silent blocks and prolongation of sounds.- Repeated movements
- * Syllable repetition—a single syllable word is repeated or a part of a word which is still a full syllable such as "un-un-under the ..." and "o-o-open".
- * Incomplete syllable repetition—an incomplete syllable is repeated, such as a consonant without a vowel, for example, "c-c-c-cold".
- * Multi-syllable repetition—more than one syllable such as a whole word, or more than one word is repeated, such as "I know-I know-I know a lot of information."
- Prolongations
- * With audible airflow—prolongation of a sound occurs such as "mmmmmmmmmom".
- * Without audible airflow—such as a block of speech or a tense pause where no airflow occurs and no phonation occurs.
The moment of stuttering often begins before the disfluency is produced, described as a moment of "anticipation"—where the person who stutters knows which word they are going to stutter on. The sensation of losing control and anticipation of a stutter can lead people who stutter to react in different ways including behavioral and cognitive reactions. Some behavioral reactions can manifest outwardly and be observed as physical tension or struggle anywhere in the body.
Outward physical behaviors
People who stutter may have reactions, avoidance behaviors, or secondary behaviors related to their stuttering that may look like struggle and tension in the body. These could range anywhere from tension in the head and neck, behaviors such as snapping or tapping, or facial grimacing.Behavioral reactions
These behavioral reactions are those that might not be apparent to listeners and only be perceptible to people who stutter. Some people who stutter exhibit covert behaviors such as avoiding speaking situations, substituting words or phrases when they know they are going to stutter, or use other methods to hide their stutter.Feelings and attitudes
Stuttering could have a significant negative cognitive and affective impact on the person who stutters. Joseph Sheehan described this in terms of an analogy to an iceberg, with the immediately visible and audible symptoms of stuttering above the waterline and a broader set of symptoms such as negative emotions hidden below the surface. Feelings of embarrassment, shame, frustration, fear, anger, and guilt are frequent in people who stutter, and may increase tension and effort. With time, continued negative experiences may crystallize into a negative self-concept and self-image. People who stutter may project their own attitudes onto others, believing that the others think them nervous or stupid. Such negative feelings and attitudes may need to be a major focus of a treatment program.The impact of discrimination against stuttering can be severe. This may result in fears of stuttering in social situations, self-imposed isolation, anxiety, stress, shame, low self-esteem, being a possible target of bullying or discrimination, or feeling pressured to hide stuttering. In popular media, stuttering is sometimes seen as a symptom of anxiety, but there is no direct correlation in that direction.
Alternatively, there are those who embrace stuttering pride and encourage other stutterers to take pride in their stutter and to find how it has been beneficial for them.
According to adults who stutter, however, stuttering is defined as a "constellation of experiences" expanding beyond the external disfluencies that are apparent to the listener. Much of the experience of stuttering is internal and encompasses experiences beyond the external speech disfluencies, which are not observable by the listener.
Associated conditions
Stuttering can co-occur with other disabilities. These associated disabilities include:- attention deficit hyperactivity disorder ; the prevalence of ADHD in school-aged children who stutter is.
- dyslexia; the prevalence rate of childhood stuttering in dyslexia is around 30–40%, while in adults the prevalence of dyslexia in adults who stutter is around 30–50%.
- autism
- intellectual disability
- language or learning disability
- seizure disorders
- social anxiety disorder
- speech sound disorders
- other developmental disorders
Causes
Various hypotheses suggest multiple factors contributing to stuttering. There is strong evidence that stuttering has a genetic basis. Children who have first-degree relatives who stutter are three times as likely to develop a stutter. In a 2010 article, three genes were found by Dennis Drayna and team to correlate with stuttering: GNPTAB, GNPTG, and NAGPA. Researchers estimated that alterations in these three genes were present in 9% of those who have a family history of stuttering.
There is evidence that stuttering is more common in children who also have concurrent speech, language, learning or motor difficulties. For some people who stutter, congenital factors may play a role. In others, there could be added impact due to stressful situations. However there is no evidence to suggest this as a cause.
Less common causes of stuttering include neurogenic stuttering and psychogenic stuttering.
History of causes
Auditory processing deficits were proposed as a cause of stuttering due to differences in stuttering for deaf or Hard of Hearing individuals, as well as the impact of auditory feedback machines on some stuttering cases.Some possibilities of linguistic processing between people who stutter and people who do not has been proposed. Brain scans of adult stutterers have found greater activation of the right hemisphere, than of the left hemisphere, which is associated with speech. In addition, reduced activation in the left auditory cortex has been observed.
The 'capacities and demands model' has been proposed to account for the heterogeneity of the disorder. Speech performance varies depending on the 'capacity' that the individual has for producing fluent speech, and the 'demands' placed upon the person by the speaking situation. Demands may be increased by internal factors or inadequate language skills or external factors. In stuttering, severity often increases when demands placed on the person's speech and language system increase. However, the precise nature of the capacity or incapacity has not been delineated. Stress, or demands, can impact many disorders without being a cause.
Another theory has been that adults who stutter have elevated levels of the neurotransmitter dopamine.
It was once thought that forcing a left-handed student to write with their right-hand due to bias against left-handed people caused stuttering, but this myth died out.
Diagnosis
Some characteristics of stuttered speech are not as easy for listeners to detect. As a result, diagnosing stuttering requires the skills of a licensed speech–language pathologist. Diagnosis of stuttering employs information both from direct observation of the individual and information about the individual's background, through a case history. The SLP may collect a case history on the individual through a detailed interview or conversation with the parents. They may also observe parent-child interactions and observe the speech patterns of the child's parents. The overall goal of assessment for the SLP will be to determine whether a speech disfluency exists, and assess if its severity warrants concern for further treatment.During direct observation of the client, the SLP will observe various aspects of the individual's speech behaviors. In particular, the therapist might test for factors including the types of disfluencies present, their frequency and duration, and speaking rate, words per minute ). They may also test for naturalness and fluency in speaking, test of childhood stuttering ) and physical concomitants during speech. They might also employ a test to evaluate the severity of the stuttering and predictions for its course. One such test includes the stuttering prediction instrument for young children, which analyzes the child's case history, and stuttering frequency in order to determine the severity of the disfluency and its prognosis for chronicity for the future.
Stuttering is a multifaceted, complex disorder that can impact an individual's life in a variety of ways. Children and adults are monitored and evaluated for evidence of possible social, psychological or emotional signs of stress related to their disorder. Some common assessments of this type measure factors including: anxiety, attitudes, perceptions of self, quality of life, behaviors, and mental health.
Clinical psychologists with adequate expertise can also diagnose stuttering per the DSM-5 diagnostic codes. The DSM-5 describes "Childhood-Onset Fluency Disorder " for developmental stuttering, and "Adult-onset Fluency Disorder". However, the specific rationale for this change from the DSM-IV is ill-documented in the APA's published literature, and is felt by some to promote confusion between the very different terms fluency and disfluency.