Part 1: What’s new in stuttering research
Treating young children who stutter: Indirect or direct?
A recent study1 used a randomized control trial (highest level of evidence), to determine the effectiveness of Lidcombe vs. RESTART-DCM for treating preschool children who stutter. The researchers found that at 18 months, clinical outcomes for direct and indirect treatment were comparable. The authors conclude that both treatments are equally effective in treating developmental stuttering in ways that surpass expectations of natural recovery.
Mice that stutter: Genetics and stuttering
- Mice with a GNPTAB mutation (a gene thought to be involved in stuttering) displayed less vocalizations and more frequent longer pauses than mice without the mutation2.
- The genes identified in stuttering all point to a single process, intracellular trafficking, but only account for at most 20% of persistent stuttering cases3.
- Bottom line: Stuttering is genetic, but this isn’t the whole picture.
The brain and stuttering
There are differences in brain structure (anatomy) and function (how the systems work together) in children who stutter, involving both auditory and motor areas of the brain4. New research is examining the difference in brains of children who persist in their stuttering versus children who recover. Brain scans show that children who persist have a deficit in the speech network in the left hemisphere. Children who recover, however, display a compensatory mechanism in the left hemisphere5.
What actually causes stuttering?
We are converging on a multifactorial dynamic pathways theory of stuttering involving the interaction of genes and the environment.
The newest research6 defines the causes of stuttering as follows:
“Stuttering is a neurodevelopmental disorder that begins during the preschool years when emerging neural networks critical for speech motor development produce unstable, aberrant control signals that give rise to stuttering-like disfluencies (SLDs). The occurrences of involuntary disruptions in speech, in turn, produce responses in the child’s internal and external milieu at both behavioral and physiological levels. These processes then may have epigenetic influences on the expression of genes involved in the development of speech motor systems. The speech motor systems in children who persist remain vulnerable to breakdowns with increasing language and psychosocial demands. Brain adaptations are inadequate and compensatory neural processes are not successful. The speech motor behaviors become overlearned patterns, interfering with fluent speech in adolescent and adulthood."
Bottom line: There is no one single cause of stuttering. Subtle weaknesses across different domains (brain, speech, temperament, environment etc.) interact to create the disorder of stuttering. Although there are many theories delving into these individual domains, that's all we know for now.
Language and executive functioning
Studies point to subtle weaknesses in language7 (not disordered) and clinically significant difficulties with executive functioning8 in children who stutter.
Druker and colleagues9 examined 185 preschool children who stutter and found that 50% of participants exhibited elevated ADHD symptoms. These kids required 25% more clinical intervention time to achieve successful fluency outcomes. The authors suggest tailoring stuttering intervention to address these concomitant behavior challenges.
What would happen if you forgot you stutter? The role of anticipation in stuttering
Anticipation is the cognitive sense that a moment of overt stuttering is imminent. Adults who stutter report that they anticipate “often.” In a recent study, all participants reported employing some kind of strategy (both avoidances and self-management) to change their speech production in response to anticipation10.
Stigma, self-help, and quality of life
First, some definitions11:
Public stigma: what society believes about and how they act toward a stigmatized group; these includes stereotypes, prejudice, and discrimination
Self-stigma: individual applies the stigma to others with the condition in general and to himself or herself personally
What you should know:
- Self-stigma is associated with lower physical health, more stress, and lower health care satisfaction in adults who stutter12.
- Stuttering is associated with reduced earnings, over $8,000 unexplained difference between males who stutter vs. males who do not stutter13.
Stigma is often associated with covert stuttering (hiding your stuttering, passing as fluent, etc.). Recent research14 examined how people transition from covert stuttering to overt stuttering. The researchers noted three things important in this shift: attending speech therapy, meeting other people who stutter, and hitting a psychological low point.
In addition to looking at stigma, researchers are beginning to examine the effects of self-disclosure of stuttering, or telling others that you are a person who stutters15, 16.
- 48.2% of participants reported that they feel the need to hide the fact that they stutter
- 37% reported that in many areas of life, no one knows that they stutter
- There is a positive association between disclosure and well-being
- Being involved in support groups increased disclosure of stuttering
- Educational, direct statements, especially when interviewing for a job are most common
Research17 also uncovers positive effects of self-help groups. People who attended National Stuttering Association chapters and the national conference:
- Were less likely to avoid speaking situations
- Were more likely to talk about stuttering
- Were more likely to have successful speech therapy
- Reported that stuttering interfered less with work and school
Putting it all together
- There is a genetic component to stuttering, but this does not account for everything
- Structural and functional differences in the brains of people who stutter
- Language and executive functioning weaknesses in PWS – this drives assessment and treatment
- Stuttering is often associated with anticipation – treat the whole disorder, not just the speech
- Attending self-help groups and self-disclosing stuttering are ways that PWS can reduce stigma and improve quality of life - this should not be an afterthought.
- de Sonneville-Koedoot, C., Stolk, E., Rietveld, E., & Franken, M. C. (2015). Direct versus indirect treatment for preschool children who stutter: The RESTART randomized trial. PLoS ONE, 10(7).
- Barnes, T. D., Wozniak, D. F., Gutierrez, J., Han, T., Drayna, D., & Holy, T. E. (2016). A mutation associated with stuttering alters mouse pup ultrasonic vocalizations. Current Biology, 26(8), 1009-1018.
- Frigerio-Domingues, C. & Drayna, D. (2017). Genetic contributions to stuttering: the current evidence. Molecular Genetics Genomic Medicine, 5(2), 95-102.
- Chang, S. E. (2014). Research updates in neuroimaging studies of children who stutter. Seminars in Speech and Language, 35(2), 67-79.
- Garnett, E. O., Chow, H. M., Nieto-Castanon, A., Tourville, J. A., Guenther, F. H., & Chang, S. E. (2018). Anomalous morphology in left hemisphere motor and premotor cortex of children who stutter. Brain, 141(9), 2670-2684.
- Smith, A., & Weber, C. (2017). How stuttering develops: The multifactorial dynamic pathways theory. Journal of Speech, Language, and Hearing Research, 60, 2483–2505.
- Leech, K.A., Bernstein Ratner, N., Brown, B., & Weber, C. M. (2017). Preliminary evidence that growth in productive language differentiates childhood stuttering persistence and recovery. Journal of Speech Language Hearing Research, 60(11), 3097-3109.
- Ntourou, K., Anderson, J. D., & Wagovich, S. A. (2018). Executive function and childhood stuttering: Parent ratings and evidence from a behavioral task. Journal of Fluency Disorders, 56, 18-32.
- Druker, K., Hennessey, N., Mazzucchelli, T., & Beilby, J. (2018). Elevated attention deficit hyperactivity disorder symptoms in children who stutter. Journal of Fluency Disorders, in press.
- Jackson, E. S., Yaruss, J. S., Quesal, R. W., Terranova, V., & Whalen, D. H. (2015). Responses of adults who stutter to the anticipation of stuttering. Journal of Fluency Disorders, 45, 38-51.
- Boyle, M. P. & Blood, G. W. (2015). Stigma and stuttering: Conceptualizations, applications, and coping.
- Boyle, M. P. & Fearon, A. N. (2018). Self-stigma and its associations with stress, physical health, and health care satisfaction in adults who stutter. Journal of Fluency Disorders, 56, 112-121.
- Gerlach, H., Totty, E., Subramanian, A., & Zebrowski, P. (2018). Stuttering and labor market outcomes in the United States. Journal of Speech, Language, and Hearing Research, 61(7), 1649-1663.
- Douglass, J. E., Schwab, M., Alvarado, J. (2018). Covert stuttering: Investigation of the paradigm shift from covertly stuttering to overtly stuttering. American Journal of Speech-Language Pathology, 27, 1235-1243.
- Boyle, M. P., Milewski, K. M., & Beita-Ell, C. (2018). Disclosure of stuttering and quality of life in people who stutter. Journal of Fluency Disorders, 58, 1-10.
- McGill, M., Siegal, J. Nguyen, D., & Rodriguez, S. (2018). Self-report of disclosure statements for stuttering. Journal of Fluency Disorders, 58, 22-34.
- Trichon, M. & Tetnowski, J. (2011). Self-help conferences for people who stutter: A qualitative investigation. Journal of Fluency Disorders, 36(4), 290-295.