Speech Disorders in Down Syndrome: A Brief Narrative Review Study

Document Type : Review Articles


MSc, Student Research Committee AND Department of Speech Therapy, School of Rehabilitation Sciences, Isfahan University of Medical Sciences, Isfahan, Iran



Introduction: The speech intelligibility of people with Down syndrome (DS) is often weak, which may not necessarily improve with age. In contrast, phonological development may be monotonous and slow; therefore, speech therapy is needed for improving speech intelligibility. In this regard, there is a variety of information in the field of speech production and related disorders in the DS population. This study reviews some features of speech production like verbal apraxia in these people, the features that may interfere with the listener's understanding and reduce the clarity of the speaker's speech. Then, the study provides some general solutions to improve the speech of these people.
Materials and Methods: : In this review study, articles were searched by using the following keywords: "Down syndrome", "speech intelligibility", "verbal apraxia", and intervention or treatment or rehabilitation in Google Scholar and Science Direct databases in the years 2000 to 2022.
Results: Out of 193 original articles found, 13 described the speech characteristics of people with DS and only one study considered oral-verbal apraxia and its treatment.
Conclusion: The literature review has provided various information about the speech characteristics of people with DS. Although the etiology classes may not directly contribute to the clinical interventions, knowing the strengths and weaknesses in the profile of people with DS along with a specialized diagnosis may help speech and language therapists to make accurate assessments and treatment plans. Besides, reviewing the literature indicates that most of the studies have described different aspects of speech disorders in people with DS. Therefore, interventional studies should be done to find the most effective treatment methods to improve the speech intelligibility of people with DS, especially to treat their verbal apraxia.


Main Subjects

  1. Bray M. Speech production in people with Down syndrome [Online]. [cited 2008 July]; Available from: URL: https://library.down-syndrome.org/en-gb/research-practice/online/2008/speech-production-people-down-syndrome/.
  2. Valizadeh A, Fatehi F, Yavari A, Dalvand H, Molai N, Faraji F, et al. Speech intelligibility in Persian children with down syndrome. Iran Rehabil J 2015; 13(4): 80-4.
  3. Roberts J, Long SH, Malkin C, Barnes E, Skinner M, Hennon EA, et al. A comparison of phonological skills of boys with fragile X syndrome and Down syndrome. J Speech Lang Hear Res 2005; 48(5): 980-95.
  4. Dodd B, Thompson L. Speech disorder in children with Down's syndrome. J Intellect Disabil Res 2001; 45(Pt 4): 308-16.
  5. Stoel-Gammon C. Down syndrome phonology: Developmental patterns and intervention strategies. Downs Syndr Res Pract 2001; 7(3): 93-100.
  6. Folden M. Down syndrome and childhood apraxia of speech: Matching a unique psycholinguistic profile to an effective treatment program [MSc Thesis]. Montréal, Canada: McGill University; 2016.
  7. Cleland J, Wood S, Hardcastle W, Wishart J, Timmins C. Relationship between speech, oromotor, language and cognitive abilities in children with Down's syndrome. Int J Lang Commun Disord 2010; 45(1): 83-95.
  8. Pettinato Ml, Verhoeven J. Production and perception of word stress in children and adolescents with Down syndrome. [Online]. [cited 2009 Sep]; Available from: URL: https://library.down-syndrome.org/en-gb/research-practice/online/2009/production-perception-word-stress-adolescents-down-syndrome
  9. Van BJ. Articulation in Down's syndrome adolescents and adults. Eur J Disord Commun 1996; 31(4): 415-44.
  10. Wild A, Vorperian HK, Kent RD, Austin D, Reinicke E. Speech intelligibility in Down syndrome: A developmental perspective [Poster]. ASHA Convention 2015; 2015 Nov 12; Denver, CO, USA.
  11. Kumin L, Von Hagel KC, Bahr DC. An effective oral motor intervention protocol for infants and toddlers with low muscle tone. Infant-Toddler Intervention 2001; 11(3-4): 181-200.
  12. Matthews-Brzozowska T, Cudzilo D, Walasz J, Kawala B. Rehabilitation of the orofacial complex by means of a stimulating plate in children with Down syndrome. Adv Clin Exp Med 2015; 24(2): 301-5.
  13. Martin GE, Klusek J, Estigarribia B, Roberts JE. Language characteristics of individuals with Down syndrome. Top Lang Disord 2009; 29(2): 112-32.
  14. Lanter E, Russell SD, Kuriakose A, Blevins KE. Incorporating AAC and general instructional strategies in requesting interventions: A case study in Down syndrome. Commun Disord Q 2015; 38(1): 52-63.
  15. Kumin L. Speech intelligibility and childhood verbal apraxia in children with Down syndrome. Downs Syndr Res Pract 2006; 10(1): 10-22.
  16. Kent RD, Vorperian HK. Speech impairment in Down syndrome: A review. J Speech Lang Hear Res 2013; 56(1): 178-210.
  17. Rupela V, Velleman SL, Andrianopoulos MV. Motor speech skills in children with Down syndrome: A descriptive study. Int J Speech Lang Pathol 2016; 18(5): 483-92.
  18. Hodson BW. Identifying phonological patterns and projecting remediation cycles: Expediting intelligibility gains of a 7 year old Australian child. Advances in Speech Language Pathology 2006; 8(3): 257-64.
  19. Wild A, Vorperian HK, Kent RD, Bolt DM, Austin D. Single-word speech intelligibility in children and adults with Down syndrome. Am J Speech Lang Pathol 2018; 27(1): 222-36.
  20. Wilson EM, Abbeduto L, Camarata SM, Shriberg LD. Speech and motor speech disorders and intelligibility in adolescents with Down syndrome. Clin Linguist Phon 2019; 33(8): 790-814.

Coppens-Hofman MC, Maassen BAM, Van Schrojenstein Lantman-De Valk HM J, Snik AFM. Speech difficulties and poor speech intelligibility in adults with Down syndrome: A review of the literature. J Hear Sci 2012; 2(1): 9-16.