Stuttering
Stuttering in Individuals with Down Syndrome: Understanding, Gaps, and Therapy Approaches
Jennifer Gray, MS, CCC-SLP
Introduction
People living with Down syndrome have multiple speech and language disorders simultaneously due to the many systems affected by a third 21st chromosome. These systems include anatomy and physiology, dynamic hearing and vision differences, executive dysfunction, cognitive language delays, gross and fine motor
Down syndrome (DS) is a genetic condition characterized by the presence of an extra copy of chromosome 21, often associated with intellectual disability, distinct physical features, and developmental delays—including speech and language impairments. Among these challenges, fluency disorders such as stuttering are often observed but remain understudied and underrecognized in this population. This article explores the prevalence, contributing factors, and best therapy practices for addressing stuttering in individuals with Down syndrome.
Prevalence and Characteristics of Stuttering in Down Syndrome
I became a Speech-Language Pathologist because I wanted to help people who stutter. To date, stuttering remains a mystery. We do not have a cure nor can we predict it’s occurrence. Treatments are still being developed to address different types of stuttering in various populations. The unknown elements of stuttering still appeals to me today. Like most of us, our career paths take on their own path, and I began working with people with Down syndrome.
Stuttering, a disorder that disrupts the forward flow of speech through repetitions, prolongations, or blocks, occurs at a significantly higher rate in individuals with Down syndrome than in the general population. Research estimates that up to 45–53% of children and adults with Down syndrome exhibit features of stuttering (Abbeduto et al., 2001; Bothe & Richardson, 2011), compared to about 1% in the general population. This astonishing difference, however, has not alerted our attention to the disruptive elements stuttering has on speech clarity.
Because people with Down syndrome have multiple speech and language delays and disorders simultaneously, stuttering is often unrecognized as it’s own speech disorder, but a consequence language complexity has on the motor act of speech. Many parents and therapists don’t recognize the speech characteristics of repeated sounds and blocking of sounds when speaking. When untreated, stuttering can become handicapping.
Key Characteristics of Stuttering in DS:
Late onset: May begin in later childhood or adolescence, contrasting with typical developmental stuttering (which usually emerges between ages 2–5 years). Most adults with Down syndrome have experienced stuttering in their lifetime and many experience worsening symptoms later in life.
Atypical disfluencies: Severe blocks when beginning to speak and more frequent whole-word and phrase repetitions, and rapid syllable repetitions within words, differing from classic stuttering behaviors.
Cognitive and linguistic impact: Slower cognitive processing, auditory memory difficulty, verbal language delays, and reduced self-awareness contribute to increased dysfluency.
Lack of Research and Awareness
Despite the high prevalence, stuttering in the Down syndrome population is poorly understood. Most research on stuttering excludes individuals with intellectual disabilities, leading to:
Limited diagnostic clarity: Many clinicians mislabel stuttering as a natural part of Down syndrome communication rather than as a treatable fluency disorder.
Scarce evidence-based interventions: Therapy approaches for the general population may not be appropriate or effective without adaptation.
Underreported by caregivers: Disfluency is often overshadowed by broader communication or cognitive challenges.
Contributing Factors
Several factors intersect to increase the likelihood of stuttering in this population:
Language formulation difficulties: Delays in expressive syntax can make it harder for individuals to construct grammatically correct sentences, leading to speech disruptions.
Oral-motor issues: Hypotonia (low muscle tone), dysarthria, motor planning, mouth breathing, smaller oral cavity, and hearing loss affects articulation and fluency.
Working memory deficits: Impaired short-term memory can disrupt the ability to plan and sequence speech efficiently.
Lack of speech practice , especially longer utterances attempted at older ages.
Learned Anxiety and self-monitoring challenges: Most have little self-awareness abilities and do not hear or recognize their own speech errors, dysfluencies, or the response others have when they are not understood. Most people with Down syndrome don’t learn to monitor their own speech and rely on others to tell them. incorporate the Increased awareness of speech errors without the cognitive flexibility to adjust can exacerbate disfluencies.
Limited research and Down syndrome-specific treatment innovations have left Speech-Language Pathologists to use the same therapies for those with Down syndrome as those without Down syndrome. This often leads to poor therapy outcomes. While therapy must be highly individualized, it should also be tailored to the phenotypical presentation of stuttering for those with trisomy 21. Making the speaker aware of their stuttered speech may also be a common first step. In the past, many thought drawing attention to stuttered speech would increase anxiety or avoidance of speech, but it actually improves awareness and leads to self-correction and speaking confidence.
Treatments for stuttering are generally grouped into 2 categories: One addresses stuttering at the moment it happens (modification), while the other uses a speaking style that is incompatible with stuttered speech (fluency shaping). Determining which to use can be determined through an evaluation process that trials techniques for the best fit and outcome. Because stuttering may be only one of several speech targets in therapy, techniques chosen should limit the complexity of the technique to match the speaker’s working memory. The unpredictable nature of stuttering in the Down syndrome population makes fluency shaping a preferred first choice due to its use at all times. Such techniques include a manner of speaking for all purposeful speech (louder, quieter, slower, rhythmic, and continuous voicing/melodic intonation. Remembering to speak one way all the time is less complex than applying a technique after stuttered speech is initiated.
Techniques that are incompatible with stuttering (stuttering can’t occur when using the technique) such as using a louder voice or melodic intonation (continuous voicing like singing) automatically slows the rate of speech, emphasizes consonants/syllable accuracy, maintains voicing, and prohibit repetitions and blocks. Remembering one way of speaking that targets multiple disorders (articulation, motor planning, vocal quality, and healthy vocal use) is ideal for those with executive functioning needs. Repetitive and applied practice creates self-awareness (alerting the speaker of own errors) and engages neuroplasticity/habit over time, enhancing carryover and maintenance of fluency and speech clarity.
1. Indirect Therapy (for younger children)
Parent-focused models like the Lidcombe Program, adapted for cognitive level, may help reduce stuttering severity.
Reduce communicative pressure by slowing speaking rate, using pauses, and modeling easy speech.
2. Direct Therapy (for older children and adults)
Fluency shaping techniques: Teach strategies such as slow, smooth speech, easy onsets, and continuous phonation.
Stuttering modification: Focus on reducing struggle and desensitizing negative reactions to stuttering (e.g., voluntary stuttering).
Combine with visual supports and repetition for individuals with intellectual disability.
3. AAC Support
Augmentative and Alternative Communication (AAC) systems may help reduce the pressure to speak fluently and allow for more relaxed communication.
4. Pragmatic and Expressive Language Goals
Target syntax, vocabulary, and social communication to reduce cognitive-linguistic load on speech production.
Use structured scripts and role-play to promote smoother speech in everyday scenarios.
5. Family and Environmental Involvement
Train parents, teachers, and caregivers to support fluency strategies and create low-pressure communication environments.
Emphasize functional outcomes over perfect fluency.
Conclusion
Stuttering is a significant yet underacknowledged issue in individuals with Down syndrome. While more research is urgently needed, clinicians can draw on existing principles of fluency therapy, cognitive-behavioral support, and family involvement to create effective interventions. Recognizing stuttering in this population—and treating it with compassion, expertise, and evidence-based tools—can dramatically improve quality of life and communicative confidence.
References
Abbeduto, L., Warren, S. F., & Conners, F. A. (2007). Language development in Down syndrome: From the prelinguistic period to the acquisition of literacy. Mental Retardation and Developmental Disabilities Research Reviews, 13(3), 247-261.
Bothe, A. K., & Richardson, J. D. (2011). Stuttering in individuals with Down syndrome: A review of the literature. Journal of Fluency Disorders, 36(4), 225–243.
Chapman, R. S. (2006). Language learning in Down syndrome: The speech and language profile compared to adolescents with cognitive impairment of unknown origin. Down Syndrome Research and Practice, 10(2), 61–66.
Summary: https://www.down-syndrome.org/en-gb/library/research-practice/online/2008/speech-production-people-down-syndrome/#:~:text=Speech%20difficulties%20are%20common%20in%20people%20with,compared%20to%201%25%20in%20the%20general%20population
