Down syndrome and fragile X syndrome are two common genetic disorders that are associated with pervasive speech and language difficulties throughout the lifespan. Speech and Language Development and Intervention in Down Syndrome and Fragile X Syndrome describes the current literature on these pervasive speech and language difficulties from birth through adulthood. Consequently, this book serves as an excellent reference for researchers, clinicians, and parents who are looking for valuable information concerning the development and intervention for individuals with these disorders.

Speech and Language Development and Intervention in Down Syndrome and Fragile X Syndrome is separated into three sections, with each covering a broad topic related to Down syndrome and fragile X syndrome. Section I (Chapters 1–2) focuses on the identification and characterization of these two syndromes. Section II (Chapters 3–6) focuses on describing the speech and language profiles for these individuals across the lifespan. In addition, in Section II, the author discusses implications of these profiles for both assessment and intervention of speech and language difficulties. Section III (Chapters 7–12) focuses specifically on speech and language interventions for individuals with Down syndrome and fragile X syndrome.

In Chapter 1, by Patterson and Lott, the authors give a broad overview of the etiology of Down syndrome, including the origins of the chromosomal anomaly that causes it, the genes involved with the additional chromosome, diagnosis, an overview of development across the lifespan, and related health issues. In Chapter 2, Hagerman covers the genetics, diagnostic issues, neurobiology, clinical phenotype, neuroimaging, and health issues for individuals with fragile X syndrome. In addition, she discusses issues related to parent genotypes and the treatment of behavioral and medical problems, including pharmacological strategies.

Chapter 3, which opens Section II, by Sterling and Warren, discusses prelinguistic language development in infants and toddlers with Down syndrome and fragile X syndrome. The authors cover issues in both populations, ranging from hearing, oral motor, and phonological development to joint attention and caregiver responsiveness. In Chapter 4, Roberts, Chapman, Martin, and Moskowitz discuss the development of language in children with Down syndrome and fragile X syndrome during the preschool and school-age years. Their discussion covers three main domains of language development: vocabulary, syntax, and pragmatics. Most important, they discuss whether children with Down syndrome and fragile X syndrome demonstrate language abilities that are congruent with their level of intellectual disability, or whether they demonstrate a profile of language impairment that is specific to their disorder. The authors conclude that, although there is great variability, children with Down syndrome display relative strengths in comprehension, pragmatic skills, and gestural communication and show relative weaknesses in expressive vocabulary and syntax. Boys with fragile X syndrome demonstrate general delays in receptive and expressive language and pragmatics but show relative strengths in receptive and expressive vocabulary. Chapter 5, by McDuffie, Chapman, and Abbeduto, compares the language profiles of adolescents and young adults with Down syndrome and fragile X syndrome. Specifically, the authors review the large amount of literature on receptive and expressive language development in Down syndrome, followed by a similar review of the relatively limited research for individuals with fragile X syndrome. In addition, they discuss how gender and a comorbid diagnosis of autism may affect language in individuals with fragile X syndrome. Last, in Chapter 6, Roberts, Stoel-Gammon, and Barnes describe the expressive phonological development across the lifespan for individuals with Down syndrome and fragile X syndrome. Specifically, they describe prelinguistic vocal development, single-word productions, connected speech, and speech intelligibility of individuals with these disorders, accompanied by a discussion of potential causes and contributions to speech difficulties in these populations.

In Section III, Chapter 7, by Brady, Bredin-Oja, and Warren, the authors describe intervention techniques designed to support the development of prelinguistic and early language development for children with Down syndrome and fragile X syndrome. Furthermore, they describe how developmental transitions, such as shifts from preintentional to intentional communication, are supported by these interventions. Chapter 8, by Kumin, describes, from a clinical perspective, language intervention to support the development of three-word utterances and beyond for individuals with Down syndrome and fragile X syndrome. Kumin emphasizes the importance of approaching each clinical intervention experience with the knowledge that each case is unique and requires individualized strategies for intervention. Furthermore, the author describes the recommended practices for intervention to support vocabulary development, pragmatics, questions and responses, nonverbal communication, conversational skills, clarification and repairs, and presuppositions for children with Down syndrome and fragile X syndrome. In Chapter 9, Price and Kent describe methods for measuring and increasing speech intelligibility in individuals with Down syndrome and fragile X syndrome. Chapter 10, by Buckley and Johnson-Glenberg, describes the current literature on literacy development for children with Down syndrome, the small amount of literature on literacy for children with fragile X syndrome, similarities between the two, and ways to support literacy development for both populations. In Chapter 11, Brady describes issues related to the use of augmentative and alternative communication (AAC) for individuals with Down syndrome and fragile X syndrome. First, Brady defines AAC and the ways it can be implemented; then, the author describes how different forms of AAC may be helpful for individuals with Down syndrome and fragile X syndrome as a function of the specific language profiles generally exhibited by these individuals. Last, in Chapter 12, Esbensen, Seltzer, and Abbeduto describe family systems and how well being is impacted, positively and negatively, by having a child with Down syndrome and fragile X syndrome.

As we already mentioned, Speech and Language Development and Intervention in Down Syndrome and Fragile X Syndrome is an excellent resource for researchers, clinicians, and parents. The book contains cutting-edge information pertaining to many areas of interest, including genetics, diagnosis and treatment, language profiles across the lifespan, speech and literacy development, communication through augmented means, and overall well being. Researchers will find the book an invaluable reference for questions related to the development of communication and language for individuals with these disorders. Likewise, clinicians will find the book informative in developing intervention protocols for affected individuals. Last, parents of individuals with Down syndrome and fragile X syndrome will find the book filled with easy to understand information that will help them make informed decisions related to health concerns, education, and intervention.

Many of the chapters of this book emphasize the importance of parent involvement in the prevention and intervention of communication and language difficulties for children with Down syndrome and fragile X syndrome. Interventionists and clinicians have only a few hours a week to facilitate change in the children with whom they work. Because children spend a majority of their time during day-to-day activities with parents, caregivers may be very effective agents for prevention and change of speech and language difficulties.

Related to the importance of parent involvement is the importance of understanding transactional influences on communication and language development and capitalizing on these influences in language intervention. The chapters in this book repeatedly highlight phenotypic characteristics of children with Down syndrome and fragile X syndrome that may impact the interaction between caregivers and children. For example, children with Down syndrome seem to have a relative advantage in the realm of gestural communication compared with their speech-production skills. This relative strength can be used to support the overall development of communication and language, in part, by teaching parents to be more sensitive to gestural forms of communication in everyday contexts. This advantage in gestural communication makes interventions involving AAC (e.g., manual signs, speech-generating devices) suitable and may be ideal for children with Down syndrome. On a related note, in Chapter 3 Sterling and Warren state that if a child with Down syndrome or fragile X syndrome has not begun to speak by Age 3, practitioners should consider using AAC strategies. The early-intervention literature suggests that practitioners should not be limited by a child's age when choosing to use AAC intervention approaches to “augment” spoken language early in the language development process. Likewise, boys (and some girls) with fragile X syndrome may exhibit symptoms of social anxiety that may make pragmatic aspects of communication difficult. Through education and involvement in intervention, parents may be taught to engage and respond to their children with this syndrome in ways that will reduce anxiety and encourage communication.

Last, this book, whether directly intended by the editors and authors, shines a bright light on the dearth of research on children with fragile X syndrome. This is particularly true for very young children and girls with fragile X. In fact, of the 12 chapters in this book, 10 comment specifically about the lack of research on speech and language development involving participants with this disorder. Additional research is needed to answer questions related to recommended early-intervention practices, the nature of gender differences for individuals with fragile X, and early language profiles for affected young children, and others. Consequently, this book serves as a very important call for action for scientists who work in the area of communication and language difficulties.

In summary, we recommend this book to parents, clinicians, and researchers as a resource of up-to-date information concerning the development, prevention, and treatment of speech and language difficulties for children with Down syndrome and fragile X syndrome.