OVERVIEW OF CHILDHOOD SPEECH AND LANGUAGE DISORDERS

Language Disorders

As described above, language refers to the code, or system of symbols, for representing ideas in various modalities, including hearing and speaking, reading, and writing. Language may also refer to the ability to interpret and produce manual communication, such as American Sign Language. Language disorders interfere with a child's ability to understand the code, to produce the code, or both (American Psychiatric Association, 2013; WHO, 1992). Children with expressive language disorders have difficulty in formulating their ideas and messages using language. Children with receptive language disorders have difficulty understanding messages encoded in language. Children with expressive-receptive language disorders have difficulty both understanding and producing messages coded in language.

Language disorders may also be classified according to whether they affect pragmatics, semantics, or grammar. Pragmatic language disorders may be seen in children who generally lack social reciprocity, a contributor to the dynamic turn-taking exchanges that typify the earliest communicative interactions (e.g., Sameroff, 2009). A child with a receptive pragmatic language disorder may have difficulty understanding messages that involve abstract ideas, such as idioms, metaphors, and irony. A child with an expressive pragmatic disorder may have difficulty producing messages that are socially appropriate for a given listener or context. A child with a receptive semantic disorder may not understand as many vocabulary words as expected for his or her age, while a child with an expressive semantic disorder may find it difficult to produce the right word to convey the intended meaning accurately. A child with a receptive grammatical deficit may not understand the differences between word endings that indicate concepts such as past (walked) or present (walking), or may not understand complex sentences (e.g., The man that the boy saw was running away). Similarly, a child with an expressive grammatical disorder may produce short, incomplete sentences that lack the grammatical endings or structures necessary to express ideas clearly or completely.

Language disorders can interfere with any of these subsystems, singly or in combination. For example, children with severe pragmatic deficits may appear uninterested in communicating with others. Other children may try to communicate, but suffer from semantic disorders that prevent them from acquiring the words they need to express their messages. Still other children have normal pragmatic skills and vocabularies, but produce grammatical errors when they attempt to combine words into phrases and sentences. Finally, children with phonological disorders may be delayed in learning which sounds belong in words.

As mentioned earlier, language disorders first identified in the preschool period have been linked to learning disabilities when children enter school (Sun and Wallach, 2014). In fact, the Individuals with Disabilities Education Act (IDEA) (Section 300.8) defines a specific learning disability as “a disorder in one or more of the basic psychological processes involved in understanding or in using language, spoken or written, that may manifest itself in the imperfect ability to listen, think, speak, read, write, spell, or to do mathematical calculations.” Strong evidence suggests that early language disorders increase the risk of poor literacy, mental health, and employment outcomes well into adulthood (e.g., Atkinson et al., 2015; Clegg et al., 2015; Law et al., 2009). For this reason, children with a history of language disorders as preschoolers are monitored closely when they enter elementary school, so that services can be provided to those whose language disorders adversely affect literacy, learning, and academic achievement.

Box 2-1 summarizes the major types of speech and language disorders in children.

BOX 2-1

Types of Speech and Language Disorders in Children.

DIAGNOSING SPEECH AND LANGUAGE DISORDERS

Speech and language disorders can accompany or result from any of the conditions that interfere with the development of perceptual, motor, cognitive, or socioemotional function. Accordingly, conditions as varied as Down syndrome, fragile X syndrome, autism spectrum disorder, traumatic brain injury, and being deaf or hard of hearing are known to increase the potential for childhood speech and/or language disorders, and many children with such conditions will also have speech and language disorders. In addition, studies of children with primary speech and language disorders often reveal that they have abnormalities in other areas of development. For example, studies by Brumbach and Goffman (2014) suggest that children with primary language impairment show general deficits in gross and fine motor performance, and such children also show deficits in working memory and procedural learning (Lum et al., 2014). Conversely, some children who have primary speech sound disorders as preschoolers have deficits in reading and spelling during their elementary school years (Lewis et al., 2011). In short, considerable evidence suggests that spoken language skills, including speech sound production, constitute an integrated system and that clear deficits in one area may coexist with deficits in other areas that can compromise future development in language-related domains such as literacy. Intensive monitoring of speech and language development in such children is important for early detection and intervention to lessen the effects of speech and language disorders.

In many children, however, speech and language disorders occur for unknown reasons. In such children, diagnosing speech and language disorders is a complex process that requires assessing not only speech and language skills but also cognitive, perceptual, motor, and socioemotional development; biological, medical, and socioeconomic circumstances; and cultural and linguistic environments. Best-practice guidelines recommend evaluating across multiple domains and obtaining information from multiple sources, including a combination of formal, standardized, or norm-referenced tests; criterion-referenced observations by speech-language pathologists and other professionals; and judgments of familiar caregivers about the child's speech and language competence relative to community expectations for children of the same age (ASHA, 2004; Nelson et al., 2006, 2008; Royal College of Speech & Language Therapists, 2005; Shevell et al., 2003; Wilkinson et al., 2013).

On norm-referenced tests, children's scores are compared with average scores from large, representative samples of children of the same age. Children scoring below a cutoff value are defined as having a deficit, and severity is defined according to how far below average their scores fall. Deficits can range from mild to severe. In clinical practice, scores that fall more than two but less than three standard deviations below the mean are described as severely or extremely low; only 2.14 percent of children would be expected to score this poorly. Scores that fall three or more standard deviations below the mean are extraordinarily low; only 0.13 percent of children would be expected to score this poorly (Urbina, 2014). Figure 2-1 represents these numbers in graphic terms. It shows that only 1 child in 1,000 would be expected to score three or more standard deviations below the mean, and only about 22 children in 1,000 would score more than two but less than three standard deviations below the mean.

FIGURE 2-1

In a normative sample of 1,000 children, only 1 child (shown in orange) is expected to score three or more standard deviations below the mean. Another 22 children (shown in light green) are expected to score more than two but less than three standard (more...)

In practice, few norm-referenced speech and language tests include a separate severity category for scores that are three or more standard deviations below the mean; all scores two or more standard deviations below the mean are classified together as “severe” or “very low” (Spaulding et al., 2012). As noted in Chapter 1, these clinical criteria for defining severity are not identical to the legal standards for severity specified in the regulations for the Supplemental Security Income (SSI) program, which also considers functional limitations (that are the result of the interactive and cumulative effects of all impairments) to determine the severity. Chapter 4 includes an in-depth review of how children are evaluated for disability in the SSI eligibility determination process.

Norm-referenced testing is not always possible because children may be too young or too disabled to participate in formal standardized testing procedures. In children younger than 3 years and others incapable of formal testing, behaviors and skills are compared with those of typically developing children using criterion-referenced measures or observational checklists (Salvia et al., 2012). Some criterion-referenced measures involve detailed observations of specific skills, such as parent checklists of the number of words that children say. For example, 3-year-old children are expected to say 50 or more different words; those who fail to reach this criterion may be identified as having a significant vocabulary delay. Similarly, by 9-10 months of age, children are expected to communicate with their caregivers using nonlinguistic signals such as pointing and clapping; a 12-month-old who appears uninterested in others and fails to produce such basic communicative precursors to language may be identified as having a significant delay in the pragmatic domain of language. Still other criterion-referenced measures involve more global judgments of whether the child's language abilities are generally commensurate with those of peers, such as asking parents whether they are concerned about their child's ability to talk or understand as well as other children of the same age. In many cases, children are diagnosed as having language delays when their level of performance on some criterion-referenced skill is inconsistent with age to a significant degree, usually defined as a “percentage of delay” relative to chronological age. For example, a 24-month-old with the skills of children half her age (i.e., 12-month-old children) can be described as having a 50 percent delay; if her skills are comparable to those of 18-month-olds, she is described as having a 25 percent delay. In many states, delays of more than 20-25 percent are used to identify children under age 3 years for early intervention under Part C of the 2004 IDEA (Ringwalt, 2015).

Validated norm-referenced tests may not be available for children who are members of cultural and linguistic communities that are not represented adequately in normative samples (e.g., AERA et al., 2014; Roseberry-McKibbin, 2014). In addition, norm-referenced test scores may be influenced by such extraneous factors as additional or confounding deficits (e.g., poor vision, inability to respond actively to test items), fatigue, and emotional state on a given day (Urbina, 2014). Finally, norm-referenced testing may not adequately reflect the functional limitations that speech and language deficits impose on the child's ability to participate in some demanding, real-world contexts. For example, a child with a speech sound disorder may be able to articulate a single word reasonably clearly on a norm-referenced speech test, but be incapable of coordinating the many events necessary to produce an intelligible sentence in fast-paced, dynamic conversation. Similarly, a child with an expressive language disorder may be able to produce single words and short phrases successfully elicited by a norm-referenced test, but be incapable of producing grammatical sentences, much less stories that include them. And a child with a receptive language disorder may understand words presented individually and point to a picture on a norm-referenced test, but be unable to comprehend sentences, especially if the sentences are lengthy, complex, spoken at the normal rate of two to four words per second, or spoken in noisy or distracting environments. For all of these reasons, best diagnostic practices require that evidence from norm- and criterion-referenced testing by professionals be considered in conjunction with judgments made by people who are familiar with the child's usual functioning in his or her daily environment (e.g., Paul and Norbury, 2012).

CAUSES AND RISK FACTORS

This chapter now turns to an overview of known underlying causes of speech and language disorders, followed by a summary of factors that have been associated with an increased risk of speech and language disorders having no known cause. Although prevalence estimates are available for some of the causes described below, and speech and language disorders are frequently mentioned among their sequelae, evidence on the percentage of speech and language disorders attributable solely to the underlying condition is not available. For example, Down syndrome, a chromosomal disorder with a prevalence of 1:700 live births, causes deficits spanning multiple areas of development, including not only speech and language but also cognition and sensorimotor skills, making it difficult to quantify the syndrome's causal role specifically in speech and language disorders.

Speech and Language Disorders with Known Causes

Determining the underlying etiology of a speech or language disorder is essential to providing the child with an appropriate set of interventions and the parents with an understanding of the cause and natural history of their child's disability. A variety of congenital and acquired conditions may result in abnormal speech and/or language development. These conditions include primary disorders of hearing, as well as specific genetic diseases, brain malformation syndromes, inborn errors of metabolism, toxic exposures, nutritional deficiencies, injuries, and epilepsy.

Children who are deaf or hard of hearing provide an especially clear example of the interrelationships among the many causes and consequences of speech and language disorders in childhood (Fitzpatrick, 2015). Because adequate hearing is critically important for developing and using receptive language, expressive language, and speech, being deaf or hard of hearing can lead to speech and language disorders, which in turn contribute to socioemotional and academic disabilities. This is particularly the case when the onset of hearing problems is either congenital or acquired during the first several years of life. Therefore, it is essential that hearing be assessed in children being evaluated for speech and language disorders.

Childhood hearing loss may result from or be associated with a wide variety of causes, which are categorized in Box 2-2. Hearing may be affected by disorders of either the sensory component of the auditory system (i.e., peripheral) or the processing of auditory information within the brain (i.e., central). Peripheral causes may be either unilateral or bilateral and are subdivided into conductive types, which are due to developmental or acquired abnormalities of the structures of the outer or middle ear, and sensorineural types, which are due to a variety of disorders affecting the sound-sensing organ—the cochlea—and its nerve that goes to the brain—the cochlear nerve.

BOX 2-2

Examples of Conditions Affecting Hearing Early in Life That May Affect the Development of Speech and Language.

Conductive-related causes of reduced hearing levels include congenital structural malformations of the outer and inner ear, consequences of acute or recurrent middle-ear infections, eustachian tube dysfunction, tumors, and trauma. Sensorineural types are even more diverse. A variety of genetic disorders have been identified that affect the function of the cochlea or cochlear nerve, and the disorder may be sporadic or inherited in an autosomal dominant, autosomal recessive, or X-linked manner, depending on the specific gene. Sensorineural types may be secondary to medical illness or even treatments for babies who must be placed in neonatal intensive care units because of either prematurity or a variety of perinatal disorders, such as hypoxia (oxygen deficiency), disturbances of blood flow, infections, or hyperbilirubinemia (excessive bilirubin levels that lead to jaundice and brain dysfunction known as kernicterus). Prenatal infections due to maternal cytomegalovirus, toxoplasmosis, or rubella (TORCH infections) can have a significant congenital impact on the sensorineural hearing mechanism, as can postnatal infectious illnesses such as meningitis (inflammation of membranes around the brain and spinal cord). Ironically, the treatment of meningitis or other bacterial infections with certain antibiotics can result in decreased hearing levels, as some of these life-saving drugs are ototoxic (i.e., harmful to structures of the ear). The impact of antibiotics on central hearing function is much less common in childhood and generally does not lead to total deafness.

The best-recognized cause affecting central hearing is Landau-Kleffner syndrome, or acquired epileptic aphasia, a rare condition that typically presents in early childhood with either minimal speech and language development or loss of previously acquired speech and language due to cortical deafness secondary to persistent epileptiform activity in the electroencephalogram, even in the absence of clinical seizures. Lastly, neonatal hyperbilirubinemia (kernicterus) can impact both sensorineural and central hearing, the latter as a result of dysfunction at the level of the brainstem. Importantly, in addition to the causes described above, many factors that impact hearing are themselves caused by, or co-occur with, underlying conditions that affect other aspects of children's development.

Apart from being deaf or hard of hearing, there are a diverse set of conditions that should be considered as other potential causes of speech and language disorders, as summarized in Box 2-2. As is the case with hearing, abnormal development of anatomic structures critical to the proper generation of speech may lead to speech sound disorders or voice disorders. For example, articulation and phonological disorders may result from cleft palate. A wide variety of genetic syndromes are known to be associated with disordered speech and language development. These include well-characterized conditions that are due to an abnormal number of a specific chromosome, such as Down syndrome (associated with three rather than two copies of chromosome 21) (Tedeschi et al., 2015) or Klinefelter syndrome (which occurs in boys who have a normal Y chromosome together with two or more X chromosomes, rather than one X chromosome).

Well-recognized genetic syndromes due to a mutation in a single gene (such as fragile X syndrome, neurofibromatosis type I, Williams syndrome, and tuberous sclerosis) are associated with speech or language disorders, and current research has demonstrated that alterations in small groups of genes (copy number variations such as 16p11.2 deletion) may increase the risk of a speech or language disability. In general, when indicated by history and clinical examination, these genetic conditions can be detected with clinically available blood-based laboratory tests. Primary malformations of the central nervous system—such as hydrocephalus (an expansion of the fluid-filled cavities within the brain), agenesis of the corpus callosum (the absence of the main structure that connects the right and left hemispheres of the brain), and both gross and microscopic abnormalities of cortical development (cortical dysplasia, an abnormal layering or location of neurons)—also may be associated with speech and language disorders. In general, these primary disruptions in brain anatomy may be diagnosed by magnetic resonance imaging (MRI) and in some cases discovered via an in utero maternal-fetal ultrasound examination.

A variety of prenatal and postnatal toxic exposures may result in abnormal brain development with resultant neurodevelopmental consequences. Maternal alcohol and other substance use are well recognized in this regard, as is postnatal exposure to lead. Similarly, abnormal prenatal growth, postnatal nutritional deprivation, and hypothyroidism (underactive thyroid) have developmental consequences. Injuries to the developing brain, such as perinatal stroke from brain hemorrhages or ischemia (inadequate blood supply), accidental trauma, and nonaccidental trauma (child abuse), must also be considered, as must such neoplastic conditions as primary brain tumors, metastatic disease, and the consequences of oncological therapies (e.g., chemotherapy and radiation). Some children with cerebral palsy (a condition that results in abnormal motor development and that has numerous causes) may also have an associated speech or language disorder. In addition, speech and language disorders may be secondary to poorly controlled epilepsy associated with a variety of causes, including structural abnormalities in cortical development, genetic disorders (e.g., mutations in ion channel genes), and complex epileptic encephalopathies (e.g., West, Lennox-Gastault, or Landau-Kleffner syndromes) (Campbell et al., 2003; Feldman and Messick, 2009).

Box 2-3 presents a listing of examples of speech and language disorders with known causes.

BOX 2-3

Examples of Speech and Language Disorders with Known Causes.

PREVALENCE

Law and colleagues (2000) found that there existed no systematic synthesis of the evidence concerning the prevalence of pediatric speech and language disorders with primary causes; their observation remains true in 2015 (Wallace et al., 2015). Estimating the prevalence of these disorders with confidence is difficult for several reasons. First, because the characteristics of these disorders differ with age, the diagnostic tools by which they are identified necessarily vary in format, ranging from simple parental reports at the earliest ages to formal standardized testing at later ages. Second, because these disorders can vary in scope—from problems with relatively discrete skills (e.g., producing individual speech sounds) to problems with broader and less observable sets of abilities (e.g., drawing inferences from or comprehending language that is ambiguous, indirect, or nonliteral)—there exists no single diagnostic tool capable of addressing the full range of pediatric speech and language skills. Third, as with many pediatric psychological and behavioral disorders, diagnostic criteria involve integrating observations from multiple sources and time points.

As a result, there currently is no single reference standard for identifying pediatric speech and language disorders of primary origin in children of all ages. Instead, prevalence estimates come from studies that focused on different ages and used different diagnostic tools and criteria. Law and colleagues (2000) found a median prevalence of 5.95 percent in the four studies they reviewed; they observe that this value is consistent with several other estimates, but emphasize the need for caution pending additional evidence from well-designed population studies.

The following subsections describe prevalence estimates from studies that have attempted to distinguish speech disorders from language disorders. However, these estimates also must be viewed with caution, given differences among studies in sample composition and diagnostic criteria.

Language Disorders

As with speech disorders, estimates of the prevalence of language disorders vary across studies by age, the presence of other neurodevelopmental disorders, and the diagnostic criteria employed. Language disorders with no known cause, sometimes referred to as “specific” (or “primary”) language impairments (e.g., Reilly et al., 2014), are highly prevalent, affecting 6-15 percent of children when identified through formal norm-referenced testing in population-based samples (Law et al., 2000). This is consistent with the cutoff values of 1.0-1.5 standard deviations below the mean employed in several investigations (e.g., Tomblin et al., 1997b). By contrast, prevalence estimates are generally higher when based on parent or teacher reports. For example, in a survey of parents and teachers conducted in a nationally representative sample of 4,983 4- to 5-year-old children in Australia, McLeod and Harrison (2009) found that prevalence estimates based on parent and teacher reports were somewhat higher than those based on norm-referenced testing, with 22-25 percent of children perceived as having deficits in talking (expressive language) and 10-17 percent as having deficits in understanding (receptive language). As noted by Law and colleagues (2000), the discrepancy between prevalence rates defined according to norm- and criterion-referenced methods could be due to a number of factors, including the inability of norm-referenced tests to capture or reflect the child's language functioning in relatively more challenging situations, such as classrooms and conversations.

Language disorders that have no known cause have been reported to affect more boys than girls, but it appears that the gender imbalance is greater in clinical than in population-based samples (e.g., Pennington and Bishop, 2009). For example, the ratio of affected males to females has ranged from 2:1 to 6:1 across several clinical samples, but boys were only slightly more likely to be affected than girls (1.3:1) in a large population-based sample of U.S. kindergarten children (Tomblin et al., 1997b).

As noted earlier, many aspects of literacy depend heavily on the language knowledge and skills that children acquire before they enter school (Catts and Kamhi, 2012), and children with severe language disorders have a substantially increased risk of deficits in reading and academic achievement. Estimates vary, but children diagnosed with language disorders with no known cause as preschoolers are at least four times more likely to have reading disabilities than their unaffected peers (Pennington and Bishop, 2009). Similarly, evidence from a large-scale, prospective methodologically sound cohort study of kindergarteners followed longitudinally showed that the majority of those with language disorders with no known cause continued to exhibit language and/or academic difficulties through adolescence (Tomblin and Nippold, 2014).

One study that helped frame the committee's understanding of prevalence estimates of speech and language disorders was a study of specific language impairment conducted by Tomblin and colleagues (1997b). This study selected a geographic region in the upper Midwest of the United States and sampled rural, suburban, and urban schools within that region. All eligible 5- to 6-year-old children were systematically screened and followed up with diagnostic testing for specific language impairment. Children were not included if they spoke a language other than English, failed a hearing test, or demonstrated low functioning in nonverbal intelligence (suggesting overall lower intellectual functioning). When a cutoff 1.25 standard deviations below the mean (i.e., approximately the 10th percentile, or the lowest 10 percent of the normative sample) on at least two language scores was used, the prevalence rate of specific language impairment was estimated at 7.4 percent of kindergarten children. The prevalence of specific language impairment for boys was 8 percent and for girls was 6 percent.

When the cutoff was set at two standard deviations below the mean (i.e., approximately the 2nd percentile), the prevalence estimate dropped to 1.12 percent. Using 1.25 standard deviations below the mean as the criterion, there were slightly higher rates of specific language impairment among African American and Native American children relative to white and Hispanic children. Only 29 percent of the parents of the kindergarteners diagnosed with specific language impairment reported having been informed that their children had speech or language problems. It is important to note that large-scale epidemiological studies on autism spectrum disorder, learning disorders, and attention deficit hyperactivity disorder have clearly demonstrated that active case-finding strategies lead to higher and more accurate rates of identification of children with neurodevelopmental disorders (Barbaresi et al., 2002, 2005, 2009; CDC, 2014; Katusic et al., 2001) relative to studies depending only on parent reports. Studies that followed this sample of children with specific language impairment into their school years demonstrated that as a group, they also experienced lower academic achievement.

The Tomblin et al. (1997a) study underscores several methodological issues relevant for the current report: differences in severity level for case identification, comorbidity with other disorders considered primary disabilities, and differences in prevalence related to gender and racial or ethnic identity. Subsequent studies with the children included in this study identified low maternal and paternal education and paternal history of speech, learning, or intellectual difficulties as risk factors for specific language impairment (Tomblin et al., 1997a).

Table 2-1 provides a summary of prevalence estimates from the studies of U.S. children that the committee also reviewed. This list is not the result of a meta-analysis, nor is it exhaustive; rather, the table includes a number of well-designed studies that employed clear and consistent definitions. The committee reviewed numerous well-designed studies and meta-analyses from other countries (e.g., Beitchman et al., 1996a,b,c [Canada]; Law et al., 2000 [United Kingdom, others]; McLeod and Harrison, 2009 [Australia]). For the purposes of this study, however, the committee limited the summary of prevalence estimates to U.S. children. Table 2-1 includes the populations and conditions studied, the diagnostic criteria used to identify the conditions, and the prevalence of the conditions (or percent positive). Confidence intervals are included when available. As noted earlier, and as is evident from the table, the studies reviewed vary greatly in terms of ages, diagnostic tools or criteria, and methods used. The estimates presented in the table (in addition to estimates based on national survey data presented in Chapter 5) indicate that speech and language disorders affect between 3 and 16 percent of U.S. children.

TABLE 2-1

Estimates of the Prevalence of Speech and Language Disorders from Studies of U.S. Children.

COMMON COMORBIDITIES

An examination of comorbidities (i.e., other co-occurring conditions) of speech and language disorders is complicated by the central role of language and communication in the development and behavior of children and adolescents. Speech and language disorders are a definitional component of certain conditions, most prominently autism spectrum disorder (American Psychiatric Association, 2013). Other neurodevelopmental disorders, including cognitive impairment, are universally associated with varying degrees of delays and deficits in language and communication skills (American Psychiatric Association, 2013). In addition to their co-occurrence with a wide range of neurodevelopmental disorders, speech and language delays in toddlers and preschool-age children are associated with a significantly increased risk for long-term developmental challenges, such as language-based learning disorders (Beitchman et al., 1996a,b,c, 1999, 2001, 2014; Brownlie et al., 2004; Stoeckel et al., 2013; Voci et al., 2006; Young et al., 2002). While specific language impairments (i.e., those not associated with other diagnosable neurodevelopmental disorders) are relatively common, it is likely that substantially greater numbers of children and adolescents experience significant speech and/or language impairment associated with other diagnosable disorders. Finally, speech and language delays and deficits may lead to impairments in other aspects of a child's functional skills (e.g., social interaction, behavior, academic achievement) even when not associated with other diagnosable disorders (Beitchman et al., 1996c, 2001, 2014; Brownlie et al., 2004; Voci et al., 2006; Young et al., 2002). This section, therefore, examines the association of speech and language disorders from the following perspectives: (1) speech and language disorders that are comorbid with other diagnosable disorders, and (2) speech and language disorders in early childhood that confer a quantifiable risk for the later development of comorbid conditions. Together, these two perspectives create a comprehensive picture of the association of speech and language disorders with other neurodevelopmental disorders.

Autism spectrum disorder is a highly prevalent neurodevelopmental disorder, affecting an estimated 1 in 68 8-year-old children in the United States (CDC, 2014). By definition, all children with autism spectrum disorder have deficits in communication, ranging from a complete absence of verbal and nonverbal communication skills, to atypical language (e.g., echolalia or “scripted” language), to more subtle deficits in pragmatic (i.e., social) communication (American Psychiatric Association, 2013). The formal diagnostic criteria for autism spectrum disorder require documentation of deficits in the social-communication domain (American Psychiatric Association, 2013). In clinical practice, when children present with significant delays in the development of communication skills, autism spectrum disorder is one of the primary diagnostic considerations (Myers and Johnson, 2007).

All children and adolescents with intellectual disability have varying degrees of impairment in communication skills (American Psychiatric Association, 2013). Among those with mild intellectual disability, deficits in communication may be relatively subtle, including inability to understand or employ highly abstract language or impairment in social communication. In contrast, children and adolescents with severe or profound levels of intellectual disability may be able only to communicate basic requests, understand concrete instructions, and communicate with simple phrases or single words; others may be unable to employ or understand spoken language. A number of specific genetic disorders are directly associated with varying degrees of intellectual disability together with abnormalities of speech and language (see Box 2-3). Some of these genetic conditions often are also associated with specific profiles of speech and language impairment (Feldman and Messick, 2009). Examples include dysfluent speech in children with Down syndrome, echolalia in boys with fragile X syndrome, and fluent but superficial social language in children with Williams syndrome (Feldman and Messick, 2009).

Language-based learning disorders, including reading and written language disorders, are often associated with speech and language disorders. The association between language impairment and reading disorders has been demonstrated in studies examining the likelihood that family members of subjects with language impairment are at increased risk for reading disorder (Flax et al., 2003). Both epidemiologic and clinic-based studies have demonstrated that children with speech sound disorders and language disorders are at increased risk for reading disorder (Pennington and Bishop, 2009). Similarly, multiple studies have demonstrated a strong association between attention deficit hyperactivity disorder and speech and language disorders (Pennington and Bishop, 2009; Tomblin, 2014).

The comorbidity of speech and language disorders and other neurodevelopmental disorders may not be apparent in pre-school-age children, since these very young children may not yet manifest the developmental lags or symptoms required to make comorbid diagnoses of such conditions as learning disorders and attention deficit hyperactivity disorder. In their prospective community-based study, for example, Beitchman and colleagues (1989) found significant differences in measures of “reading readiness” among 5-year-old children with poor language comprehension compared with children with either high overall speech and language ability or isolated articulation difficulties (Beitchman et al., 1989). Similarly, there was a tendency for 5-year-olds with a combination of low articulation and poor language comprehension to have higher teacher ratings of hyperactivity and inattention and lower maternal ratings of social competence (Beitchman et al., 1989). By age 12, the children who earlier had shown combined deficits in speech and language had significantly lower levels of reading achievement and higher rates of diagnosed psychiatric disorders (57.1 percent versus 23.7 percent for children with normal speech and language at age 5) (Beitchman et al., 1994). By age 19, children with documented language impairment at age 5 had significantly higher rates of reading disorder (36.8 percent versus 6.4 percent), math disorder (53.9 percent versus 12.2 percent), and psychiatric disorders (40 percent versus 21 percent) compared with their peers with normal language ability at age 5 (Young et al., 2002).

In summary, speech and language disorders are frequently identified in association with (i.e., comorbid with) a wide range of other neurodevelopmental disorders. Children with comorbid conditions can be expected to be more severely impaired and to experience greater functional limitations (due to the interactive and cumulative effects of multiple conditions) than children who do not have comorbid conditions. Furthermore, young children with language impairments are at high risk for later manifestation of learning and psychiatric disorders. It is therefore important both to carefully examine the speech and language skills of children with other developmental disorders and to identify other neurodevelopmental disorders among children presenting with speech and language impairment. Among populations of children with conditions as diverse as autism spectrum disorder, attention deficit hyperactivity disorder, traumatic brain injury, and genetic disorders, speech and language disorders may be the most easily identified impairments because of the central role of language and communication in the functional capacity of children and adolescents.

FINDINGS AND CONCLUSIONS

REFERENCES

• Adams CD, Hillman N, Gaydos GR. Behavioral difficulties in toddlers: Impact of socio-cultural and biological risk factors. Journal of Clinical Child Psychology. 1994;23(4):373–381.
• Adams-Chapman I, Bann C, Carter SL, Stoll BJ. Language outcomes among ELBW infants in early childhood. Early Human Development. 2015;91(6):373–379. [PMC free article: PMC4442021] [PubMed: 25955535]
• AERA (American Educational Research Association), APA (American Psychological Association), and NCME (National Council on Measurement in Education). Standards for educational and psychological testing. Washington, DC: AERA; 2014.
• Akca OF, Ugur C, Colak M, Kartal OO, Akozel AS, Erdogan G, Uslu RI. Underinvolved relationship disorder and related factors in a sample of young children. Early Human Development. 2012;88(6):327–332. [PubMed: 21955500]
• American Psychiatric Association. Diagnostic and statistical manual of mental disorders: DSM-5. 5th ed. Washington, DC: American Psychiatric Association; 2013.
• ASHA (American Speech-Language-Hearing Association). Preferred practice patterns for the profession of speech-language pathology. 2004. [September 29, 2015]. http://www​.asha.org/policy/PP200400191​.htm.
• ASHA. Childhood apraxia of speech. 2007. [September 29, 2015]. http://www​.asha.org/policy/TR2007-00278​.htm.
• Atkinson L, Beitchman J, Gonzalez A, Young A, Wilson B, Escobar M, Chisholm V, Brownlie E, Khoury JE, Ludmer J, Villani V. Cumulative risk, cumulative outcome: A 20-year longitudinal study. PLoS ONE. 2015;10(6):e0127650. [PMC free article: PMC4452593] [PubMed: 26030616]
• Barbaresi WJ, Katusic SK, Colligan RC, Shane Pankratz V, Weaver AL, Weber KJ, Mrazek DA, Jacobsen SJ. How common is attention-deficit/hyperactivity disorder? Incidence in a population-based birth cohort in Rochester, Minn. Archives of Pediatrics and Adolescent Medicine. 2002;156(3):217–224. [PubMed: 11876664]
• Barbaresi WJ, Katusic SK, Colligan RC, Weaver AL, Jacobsen SJ. Math learning disorder: Incidence in a population-based birth cohort 1976-82, Rochester, Minn. Ambulatory Pediatrics. 2005;5(5):281–289. [PubMed: 16167851]
• Barbaresi WJ, Colligan RC, Weaver AL, Katusic SK. The incidence of clinically diagnosed versus research-identified autism in Olmsted County, Minnesota, 1976-1997: Results from a retrospective, population-based study. Journal of Autism and Developmental Disorders. 2009;39(3):464–470. [PMC free article: PMC2859841] [PubMed: 18791815]
• Barry JG, Yasin I, Bishop DV. Heritable risk factors associated with language impairments. Genes, Brain, and Behavior. 2007;6(1):66–76. [PMC free article: PMC1974814] [PubMed: 17233642]
• Beitchman JH, Hood J, Rochon J, Peterson M, Mantini T, Majumdar S. Empirical classification of speech/language impairment in children: I. Identification of speech/language disorders. Journal of the American Academy of Child & Adolescent Psychiatry. 1989;28(1):112–117. [PubMed: 2914823]
• Beitchman JH, Brownlie EB, Inglis A, Wild J, Mathews R, Schachter D, Kroll R, Martin S, Ferguson B, Lancee W. Seven-year follow-up of speech/language-impaired and control children: Speech/language stability and outcome. Journal of the American Academy of Child & Adolescent Psychiatry. 1994;33(9):1322–1330. [PubMed: 7995800]
• Beitchman JH, Wilson B, Brownlie EB, Walters H, Lancee W. Long-term consistency in speech/language profiles: I. Developmental and academic outcomes. Journal of the American Academy of Child & Adolescent Psychiatry. 1996a;35(6):804–814. [PubMed: 8682762]
• Beitchman JH, Wilson B, Brownlie EB, Walters H, Inglis A, Lancee W. Long-term consistency in speech/language profiles: II. Behavioral, emotional and social outcomes. Journal of the American Academy of Child & Adolescent Psychiatry. 1996b;35(6):815–825. [PubMed: 8682763]
• Beitchman JH, Brownlie EB, Inglis A, Wild J, Mathews R, Schachter D, Kroll R, Martin S, Ferguson B, Lancee W. Seven-year follow-up of speech/language impaired and control children: Psychiatric outcomes. Journal of the American Academy of Child & Adolescent Psychiatry. 1996c;37(8):961–970. [PubMed: 9119943]
• Beitchman JH, Douglas L, Wilson B, Johnson C, Young A, Atkinson L, Escobar M, Taback N. Adolescent substance use disorders: Findings from a 14-year follow-up of speech/language-impaired and control children. Journal of Clinical Child & Adolescent Psychology. 1999;28(3):312–321. [PubMed: 10446680]
• Beitchman JH, Wilson B, Johnson CJ, Atkinson L, Young A, Adlaf E, Escobar M, Douglas L. Fourteen-year follow-up of speech/language-impaired and control children: Psychiatric outcome. Journal of the American Academy of Child & Adolescent Psychiatry. 2001;40(1):75–82. [PubMed: 11195567]
• Beitchman JH, Brownlie EB, Bao L. Age 31 mental health outcomes of childhood language and speech disorders. Journal of the American Academy of Child & Adolescent Psychiatry. 2014;53(10):1102–1110. [PubMed: 25245354]
• Béna F, Bruno DL, Eriksson M, van Ravenswaaij-Arts C, Stark Z, Dijkhuizen T, Gerkes E, Gimelli S, Ganesamoorthy D, Thuresson AC, Labalme A, Till M, Bilan F, Pasquier L, Kitzis A, Dubourgm C, Rossi M, Bottani A, Gagnebin M, Sanlaville D, Gilbert-Dussardier B, Guipponi M, van Haeringen A, Kriek M, Ruivenkamp C, Antonarakis SE, Anderlid BM, Slater HR, Schoumans J. Molecular and clinical characterization of 25 individuals with exonic deletions of NRXN1 and comprehensive review of the literature. American Journal of Medical Genetics Part B: Neuropsychiatric Genetics. 2013;162(4):388–403. [PubMed: 23533028]
• Bishop DVM. What causes specific language impairment in children? Current Directions in Psychological Science. 2006;15(5):217–221. [PMC free article: PMC2582396] [PubMed: 19009045]
• Bishop DVM. Which neurodevelopmental disorders get researched and why? PLoS ONE. 2010;5(11):e15112. [PMC free article: PMC2994844] [PubMed: 21152085]
• Bishop DVM, Hayiou-Thomas ME. Heritability of specific language impairment depends on diagnostic criteria. Genes, Brain, and Behavior. 2008;7(3):365–372. [PMC free article: PMC2324210] [PubMed: 17919296]
• Bloodstein O, Ratner NB. A handbook on stuttering. 6th ed. New York: Thomson Delmar; 2008.
• Boudreau D. Narrative abilities: Advances in research and implications for clinical practice. Topics in Language Disorders. 2008;28(2):99–114.
• Brownlie EB, Beitchman JH, Escobar M, Young A, Atkinson L, Johnson C, Wilson B, Douglas L. Early language impairment and young adult delinquent and aggressive behavior. Journal of Abnormal Child Psychology. 2004;32(4):453–467. [PubMed: 15305549]
• Brumbach ACD, Goffman L. Interaction of language processing and motor skill in children with specific language impairment. Journal of Speech, Language, and Hearing Research. 2014;57(1):158–171. [PMC free article: PMC4004610] [PubMed: 24023372]
• Campbell TF, Dollaghan CA, Rockette HE, Paradise JL, Feldman HM, Shriberg LD, Sabo D, Kurs-Lasky M. Risk factors for speech delay in three-year-old children. Child Development. 2003;74:346–357. [PubMed: 12705559]
• Carding PN, Roulstone S, Northstone K. ALSPAC Study Team. The prevalence of childhood dysphonia: A cross-sectional study. Journal of Voice. 2006;20(4):623–630. [PubMed: 16360302]
• Caruso AJ, Strand EA. Clinical management of motor speech disorders in children. Caruso A, Strand E, editors. New York: Thieme; 1999. pp. 1–27. (Motor speech disorders in children: Definitions, background, and a theoretical framework).
• Catts HW, Kamhi AG. Language and reading disabilities. Boston, MA: Pearson; 2012.
• Caye-Thomasen P, Dam MS, Omland SH, Mantoni M. Cochlear ossification in patients with profound hearing loss following bacterial meningitis. Acta Oto-Laryngologica. 2012;132(7):720–725. [PubMed: 22497482]
• CDC (Centers for Disease Control and Prevention). Developmental disabilities monitoring network surveillance year 2010 principal investigators. Prevalence of autism spectrum disorder among children aged 8 years—Autism and Developmental Disabilities Monitoring Network, 11 sites, United States, 2010. Morbidity and Mortality Weekly Report Surveillance Summaries. 2014;63(2):1–21. [PubMed: 24670961]
• Chang B, Walsh CA, Apse K, Bodell A. Polymicrogyria overview. Seattle, WA: GeneReviews; 2007.
• Christakis DA, Gilkerson J, Richards JA, Zimmerman FJ, Garrison MM, Xu D, Gray S, Yapanel U. Audible television and decreased adult words, infant vocalizations, and conversational turns: A population-based study. Archives of Pediatrics and Adolescent Medicine. 2009;163(6):554–558. [PubMed: 19487612]
• Clegg J, Law J, Rush R, Peters TJ, Roulstone S. The contribution of early language development to children's emotional and behavioral functioning: An analysis of data from the Children in Focus sample from the ALSPAC birth cohort. Journal of Child Psychology and Psychiatry. 2015;56(1):67–75. [PubMed: 24980269]
• Cohen BE, Durstenfeld A, Roehm PC. Viral causes of hearing loss: A review for hearing health professionals. Trends in Hearing. 2014;18 [PMC free article: PMC4222184] [PubMed: 25080364]
• Conture EG. Stuttering: Its nature, assessment, and treatment. Needham Heights, MA: Allyn & Bacon; 2001.
• Corujo-Santana C, Falcón-González J, Borkoski-Barreiro S, Pérez-Plasencia D, Ramos-Macías Á. The relationship between neonatal hyperbilirubinemia and sensorineural hearing loss. Acta Otorrinolaringologica Espanola. 2015;66(6):326–331. [PubMed: 25638013]
• Crystal D. Dictionary of linguistics and phonetics. Hoboken, NJ: Wiley-Blackwell; 2009.
• Dennis M. Language disorders in children with central nervous system injury. Journal of Clinical and Experimental Neuropsychology. 2010;32(4):417–432. [PMC free article: PMC3057107] [PubMed: 20397297]
• DeThorne LS, Petrill SA, Hayiou-Thomas ME, Plomin R. Low expressive vocabulary: High heritability as a function of more severe cases. Journal of Speech, Language, and Hearing Research. 2005;48(4):792–804. [PubMed: 16378474]
• Dockrell J, Lindsay G, Roulstone S, Law J. Supporting children with speech, language and communication needs: An overview of the results of the Better Communication Research Programme. International Journal of Language & Communication Disorders. 2014;49(5):543–557. [PubMed: 24961589]
• Duke NK, Cartwright KB, Hilden KR. Handbook of language and literacy: Development and disorders. 2nd ed. Stone CA, Silliman ER, Ehren BJ, Wallach GP, editors. New York: Guilford Press; 2013. pp. 451–468. (Difficulties with reading comprehension).
• Dunklebarger J, Branstetter B, Lincoln A, Sippey M, Cohen M, Gaines B, Chi D. Pediatric temporal bone fractures: Current trends and comparison of classification schemes. The Laryngoscope. 2014;124(3):781–784. [PubMed: 24347062]
• Eadie P, Morgan A, Okoumunne OC, Eecen KT, Wake M, Reilly S. Speech sound disorder at 4 years: Prevalence, comorbidities, and predictors in a community cohort of children. Developmental Medicine and Child Neurology. 2015;57(6):578–584. [PubMed: 25403868]
• Earle FS, Myers EB. Building phonetic categories: An argument for the role of sleep. Frontiers in Psychology. 2014;5:1192. [PMC free article: PMC4234907] [PubMed: 25477828]
• Feldman HM, Messick C. Developmental-behavioral pediatrics. 4th ed. Carey WB, Crocker AC, Coleman WL, Elias ER, Feldman HM, editors. Philadelphia, PA: Saunders; 2009. pp. 717–729. (Language and speech disorders).
• Fenson L, Marchman VA, Thal DJ, Dale PS, Reznick JS, Bates E. MacArthur-Bates communicative development inventories. 2nd ed. Baltimore, MD: Paul H. Brookes Publishing Co.; 2007.
• Fernald A, Marchman VA, Weisleder A. SES differences in language processing skill and vocabulary are evident at 18 months. Developmental Science. 2013;16(2):234–248. [PMC free article: PMC3582035] [PubMed: 23432833]
• Fitzpatrick E. Handbook of clinical neurology, Ch. 19. Aminoff MJ, Boller F, Swaab DF, editors. Vol. 129. Philadelphia, PA: Elsevier; 2015. pp. 335–356. (Neurocognitive development in congenitally deaf children).
• Flax JF, Realpe-Bonilla T, Hirsch LS, Brzustowicz LM, Bartlett CW, Tallal P. Specific language impairment in families: Evidence for co-occurrence with reading impairments. Journal of Speech, Language, and Hearing Research. 2003;46(3):530–543. [PubMed: 14696984]
• Ford LC, Sulprizio SL, Rasgon BM. Otolaryngological manifestations of velocardiofacial syndrome: A retrospective review of 35 patients. The Laryngoscope. 2000;110(3):362–367. [PubMed: 10718420]
• Friedrich M, Wilhelm I, Born J, Friederici AD. Generalization of word meanings during infant sleep. Nature Communications. 2015;6 [PMC free article: PMC4316748] [PubMed: 25633407]
• Gallagher A, Tanaka N, Suzuki N, Liu H, Thiele EA, Stufflebeam SM. Diffuse cerebral language representation in tuberous sclerosis complex. Epilepsy Research. 2013;104(1):125–133. [PMC free article: PMC3574215] [PubMed: 23092910]
• Gejão MG, Ferreira AT, Silva GK, Anastácio-Pessan FDL, Lamônica DAC. Communicative and psycholinguistic abilities in children with phenylketonuria and congenital hypothyroidism. Journal of Applied Oral Science. 2009;17(Suppl):69–75. [PMC free article: PMC5467373] [PubMed: 21499658]
• Gillam RB, Peña ED, Bedore LM, Bohman TM, Mendez-Perez A. Identification of specific language impairment in bilingual children. Part 1: Assessment in English. Journal of Speech, Language, and Hearing Research. 2013;56:1813–1823. [PMC free article: PMC5902172] [PubMed: 23882008]
• Glynn F, Fitzgerald D, Earley MJ, Rowley H. Pierre Robin sequence: An institutional experience in the multidisciplinary management of airway, feeding and serous otitis media challenges. International Journal of Pediatric Otorhinolaryngology. 2011;75(9):1152–1155. [PubMed: 21764465]
• Goderis J, De Leenheer E, Smets K, Van Hoecke H, Keymeulen A, Dhooge I. Hearing loss and congenital CMV infection: A systematic review. Pediatrics. 2014;134(5):972–982. [PubMed: 25349318]
• Goldstein BA, Gildersleeve-Neumann C. Bilingual language development and disorders in Spanish-English speakers. Goldstein BA, editor. Baltimore, MD: Paul H. Brookes Publishing Co.; 2012. pp. 285–309. (Phonological development and disorders).
• Hanson E, Bernier R, Porche K, Jackson FI, Goin-Kochel RP, Snyder LG, Snow AV, Wallace AS, Campe KL, Zhang Y, Chen Q, D'Angelo D, Moreno-De-Luca A, Orr PT, Boomer KB, Evans DW, Kanne S, Berry L, Miller FK, Olson J, Sherr E, Martin CL, Ledbetter DH, Spiro JE, Chung WK, Simons C. The cognitive and behavioral phenotype of the 16p11.2 deletion in a clinically ascertained population. Biological Psychiatry. 2015;77(9):785–793. [PMC free article: PMC5410712] [PubMed: 25064419]
• Harrison LJ, McLeod S. Risk and protective factors associated with speech and language impairment in a nationally representative sample of 4- to 5-year-old children. Journal of Speech, Language, and Hearing Research. 2010;53(2):508–529. [PubMed: 19786704]
• Hart B, Risley T. Meaningful differences in the everyday experiences of young American children. Baltimore, MD: Paul H. Brookes Publishing Co.; 1995.
• Hoff E. Interpreting the early language trajectories of children from low-SES and language minority homes: Implications for closing achievement gaps. Developmental Psychology. 2013;49(1):4–14. [PMC free article: PMC4061698] [PubMed: 22329382]
• Hudson LJ, Murdoch B. Speech and language disorders in childhood brain tumours. Acquired Neurological Speech/Language Disorders in Childhood. 1990:245–268.
• Hurtado N, Grüter T, Marchman VA, Fernald A. Relative language exposure, processing efficiency and vocabulary in Spanish-English bilingual toddlers. Bilingualism: Language and Cognition. 2014;17(1):189–202.
• Ilves P, Tomberg T, Kepler J, Laugesaar R, Kaldoja ML, Kepler K, Kolk A. Different plasticity patterns of language function in children with perinatal and childhood stroke. Journal of Child Neurology. 2014;29(6):756–764. [PMC free article: PMC4230975] [PubMed: 23748202]
• Jambaque I, Pinabiaux C, Lassonde M. Cognitive disorders in pediatric epilepsy. Handbook of Clinical Neurology. 2012;111:691–695. [PubMed: 23622216]
• Jing W, Zongjie H, Denggang F, Na H, Bin Z, Aifen Z, Xijiang H, Cong Y, Yunping D, Ring HZ. Mitochondrial mutations associated with aminoglycoside ototoxicity and hearing loss susceptibility identified by meta-analysis. Journal of Medical Genetics. 2015;52(2):95–103. [PubMed: 25515069]
• Jurewicz J, Polanska K, Hanke W. Chemical exposure early in life and the neurodevelopment of children—an overview of current epidemiological evidence. Annals of Agricultural and Environmental Medicine. 2013;20(3):465–486. [PubMed: 24069851]
• Katusic SK, Colligan RC, Barbaresi WJ, Schaid DJ, Jacobsen SJ. Incidence of reading disability in a population-based birth cohort, 1976-1982, Rochester, Minn. Mayo Clinic Proceedings. 2001;76(11):1081–1092. [PubMed: 11702896]
• Kent RD. Clinical management of motor speech disorders in children. Caruso AJ, Strand EA, editors. New York: Thieme; 1999. pp. 29–71. (Motor control: Neurophysiology and functional development).
• Kent RD, Vorperian HK. Speech impairment in Down syndrome: A review. Journal of Speech, Language, and Hearing Research. 2013;56(1):178–210. [PMC free article: PMC3584188] [PubMed: 23275397]
• Kim YS, Apel K, Al Otaiba S. The relation of linguistic awareness and vocabulary to word reading and spelling for first-grade students participating in response to intervention. Language, Speech, and Hearing Services in Schools. 2013;44(4):337–347. [PMC free article: PMC3852899] [PubMed: 23833281]
• King TM, Rosenbert LA, Fuddy L, McFarlane E, Sia C, Duggan AK. Prevalence and early identification of language delays among at-risk three year olds. Journal of Developmental and Behavioral Pediatrics. 2005;26(4):293–303. [PubMed: 16100502]
• Klein-Tasman BP, Janke KM, Luo W, Casnar CL, Hunter SJ, Tonsgard J, Trapane P, van der Fluit F, Kais LA. Cognitive and psychosocial phenotype of young children with neurofibromatosis-1. Journal of the International Neuropsychological Society. 2014;20(1):88–98. [PMC free article: PMC4249943] [PubMed: 24229851]
• Kohnert K, Derr A. Language intervention with bilingual children. In. Goldstein BA, editor. Baltimore, MD: Paul H. Brookes Publishing Co.; Bilingual language development and disorders in Spanish-English speakers. 2012:337–356.
• Law J, Boyle J, Harris F, Harkness A, Nye C. Prevalence and natural history of primary speech and language delay: Findings from a systematic review of the literature. International Journal of Language & Communication Disorders. 2000;35(2):165–188. [PubMed: 10912250]
• Law J, Rush R, Schoon I, Parsons S. Modeling developmental language difficulties from school entry into adulthood: Literacy, mental health, and employment outcomes. Journal of Speech, Language, and Hearing Research. 2009;52(6):1401–1416. [PubMed: 19951922]
• Lewis BA, Shriberg LD, Freebairn LA, Hansen AJ, Stein CM, Taylor HG, Iyengar SK. The genetic bases of speech sound disorders: Evidence from spoken and written language. Journal of Speech, Language, and Hearing Research. 2006;49(6):1294–1312. [PubMed: 17197497]
• Lewis BA, Freebairn LA, Hansen AJ, Miscimarra L, Iyengar SK, Taylor HG. Speech and language skills of parents of children with speech sound disorders. American Journal of Speech-Language Pathology. 2007;16(2):108–118. [PubMed: 17456889]
• Lewis BA, Avrich AA, Freebairn LA, Hansen AJ, Sucheston LE, Kuo I, Taylor HG, Iyengar SK, Stein CM. Literacy outcomes of children with early childhood speech sound disorders: Impact of endophenotypes. Journal of Speech, Language, and Hearing Research. 2011;54(6):1628–1643. [PMC free article: PMC3404457] [PubMed: 21930616]
• Lewis BA, Freebairn L, Tag J, Ciesla AA, Iyengar SK, Stein CM, Taylor HG. Adolescent outcomes of children with early speech sound disorders with and without language impairment. American Journal of Speech-Language Pathology/American Speech-Language-Hearing Association. 2015;24(2):150–163. [PMC free article: PMC4477798] [PubMed: 25569242]
• Locke J. Handbook of psycholinguistic and cognitive processes: Perspectives in communication disorders. Guendouzi J, Loncke F, Williams MJ, editors. New York: Psychology Press; 2011. pp. 3–29. (The development of linguistic systems: Insights from evolution).
• Lozano R, Vino A, Lozano C, Fisher SE, Deriziotis P. A de novo FOXP1 variant in a patient with autism, intellectual disability and severe speech and language impairment. European Journal of Human Genetics. 2015;23(12):1702–1707. [PMC free article: PMC4795189] [PubMed: 25853299]
• Lum JA, Conti-Ramsden G, Morgan AT, Ullman MT. Procedural learning deficits in specific language impairment (SLI): A meta-analysis of serial reaction time task performance. Cortex. 2014;51:1–10. [PMC free article: PMC3989038] [PubMed: 24315731]
• Luquetti DV, Heike CL, Hing AV, Cunningham ML, Cox TC. Microtia: Epidemiology and genetics. American Journal of Medical Genetics Part A. 2012;158A(1):124–139. [PMC free article: PMC3482263] [PubMed: 22106030]
• McGee CL, Bjorkquist OA, Riley EP, Mattson SN. Impaired language performance in young children with heavy prenatal alcohol exposure. Neurotoxicology and Teratology. 2009;31(2):71–75. [PMC free article: PMC2683242] [PubMed: 18938239]
• McLeod S, Harrison LJ. Epidemiology of speech and language impairment in a nationally representative sample of 4- to 5-year-old children. Journal of Speech, Language, and Hearing Research. 2009;52(5):1213–1229. [PubMed: 19403947]
• Mildinhall S. Speech and language in the patient with cleft palate. Frontiers of Oral Biology. 2012;16:137–146. [PubMed: 22759677]
• Miller JF, Paul R. The clinical assessment of language comprehension. Baltimore, MD: Paul H. Brookes Publishing Co.; 1995.
• Moleski M. Neuropsychological, neuroanatomical, and neurophysiological consequences of CNS chemotherapy for acute lymphoblastic leukemia. Archives of Clinical Neuropsychology. 2000;15(7):603–630. [PubMed: 14590198]
• Morgan AT, Vogel AP. Intervention for dysarthria associated with acquired brain injury in children and adolescents. Cochrane Database of Systematic Reviews. 2008;(3):CD006279. [PMC free article: PMC6492483] [PubMed: 18646143]
• Myers SM, Johnson CP. Management of children with autism spectrum disorders. Pediatrics. 2007;120(5):1162–1182. [PubMed: 17967921]
• Næss KAB, Lervåg A, Lyster SAH, Hulme C. Longitudinal relationships between language and verbal short-term memory skills in children with Down syndrome. Journal of Experimental Child Psychology. 2015;135:43–55. [PubMed: 25819288]
• Nelson HD, Nygren P, Walker M, Panoscha R. Screening for speech and language delay in preschool children: Systematic evidence review of the US Preventive Services Task Force. Pediatrics. 2006;117(2):e298–e319. [PubMed: 16452337]
• Nelson HD, Bougatsos C, Nygren P. Universal newborn hearing screening: systematic review to update the 2001 US Preventive Services Task Force Recommendation. Pediatrics. 2008;122(1):e266–e276. [PubMed: 18595973]
• Newbury DF, Monaco AP. Genetic advances in the study of speech and language disorders. Neuron. 2010;68(2):309–320. [PMC free article: PMC2977079] [PubMed: 20955937]
• Parish SL, Grinstein-Weiss M, Yeo YH, Rose RA, Rimmerman A. Assets and income: Disability-based disparities in the United States. Social Work Research. 2010;34(2):71–82.
• Parker M, Bitner-Glindzicz M. Genetic investigations in childhood deafness. Archives of Disease in Childhood. 2015;100(3):271–278. [PubMed: 25324569]
• Patterson M, Paparella MM. Otitis media with effusion and early sequelae: Flexible approach. Otolaryngologic Clinics of North America. 1999;32(3):391–400. [PubMed: 10393775]
• Paul LK. Developmental malformation of the corpus callosum: A review of typical callosal development and examples of developmental disorders with callosal involvement. Journal of Neurodevelopmental Disorders. 2011;3(1):3–27. [PMC free article: PMC3163989] [PubMed: 21484594]
• Paul R, Norbury CF. Language disorders from infancy through adolescence: Listening, speaking, reading, writing, and communicating. 4th ed. St. Louis, MO: Elsevier; 2012.
• Pelucchi B, Hay JF, Saffran JR. Statistical learning in a natural language by 8-month-old infants. Child Development. 2009;80(3):674–685. [PMC free article: PMC3883431] [PubMed: 19489896]
• Pennington BF, Bishop DVM. Relations among speech, language, and reading disorders. Annual Review of Psychology. 2009;60:283–306. [PubMed: 18652545]
• Pennington L, Miller N, Robson S. Speech therapy for children with dysarthria acquired before three years of age. Cochrane Database of Systematic Reviews. 2009;(4):CD006937. [PubMed: 19821391]
• Pentimonti JM, Justice LJ, Kaderavek JN. School-readiness profiles of children with language impairment: Linkages to home and classroom experiences. International Journal of Language & Communication Disorders. 2014;49(5):567–583. [PubMed: 24894359]
• Perry BD, Beauchaine T, Hinshaw SP. Child maltreatment: A neurodevelopmental perspective on the role of trauma and neglect in pyschopathology. Child and Adolescent Psychopathology. 2008:93–129.
• Pinborough-Zimmerman J, Satterfield R, Miller J, Bilder D, Hossain S, McMahon W. Communication disorders: Prevalence and comorbid intellectual disability, autism, and emotional/behavioral disorders. American Journal of Speech-Language Pathology. 2007;16(4):359–367. [PubMed: 17971495]
• Plyler E, Harkrider AW. Serial auditory-evoked potentials in the diagnosis and monitoring of a child with Landau-Kleffner syndrome. Journal of the American Academy of Audiology. 2013;24(7):564–571. [PubMed: 24047944]
• Reilly S, Wake M, Ukoumunne OC, Bavin E, Prior M, Cini E, Conway L, Eadie P, Bretherton L. Predicting language outcomes at 4 years of age: Findings from Early Language in Victoria Study. Pediatrics. 2010;126(6):e1530–e1537. [PubMed: 21059719]
• Reilly S, Tomblin B, Law J, McKean C, Mensah F, Morgan A, Goldfield S, Nicholson J, Wake M. Specific language impairment: A convenient label for whom? International Journal of Language & Communication Disorders. 2014;49(4):415–433. [PMC free article: PMC4303922] [PubMed: 25142091]
• Rice ML. Toward epigenetic and gene regulation models of specific language impairment: Looking for links among growth, genes, and impairments. Journal of Neurodevelopmental Disorders. 2012;4(1):1. [PMC free article: PMC3534233] [PubMed: 23176600]
• Ringwalt S. Summary table of states' and territories' definitions of/criteria for IDEA Part C eligibility. Chapel Hill, NC: Early Childhood Technical Assistance Center; 2015.
• Robertson C, Finer N. Term infants with hypoxic-ischemic encephalopathy: Outcome at 3.5 years. Developmental Medicine & Child Neurology. 1985;27(4):473–484. [PubMed: 4029517]
• Roseberry-McKibbin C. Multicultural students with special language needs. 4th ed. Oceanside, CA: Academic Communication Associates; 2014.
• Royal College of Speech & Language Therapists. Clinical guidelines (Ch. 5.2). Taylor-Groh S, editor. Bicester, UK: Speechmark Publishing Ltd.; 2005. pp. 19–24. (Preschool children with communication, language & speech needs).
• Salvia J, Ysseldyke J, Bolt S. Assessment: In special and inclusive education. Boston, MA: Cengage Learning; 2012.
• Sameroff A. The transactional model. Washington, DC: American Psychological Association; 2009.
• Saporta AS, Kumar A, Govindan RM, Sundaram SK, Chugani HT. Arcuate fasciculus and speech in congenital bilateral perisylvian syndrome. Pediatric Neurology. 2011;44(4):270–274. [PubMed: 21397168]
• Schreiber JE, Gurney JG, Palmer SL, Bass JK, Wang M, Chen S, Zhang H, Swain M, Chapieski ML, Bonner MJ, Mabbott DJ, Knight SJ, Armstrong CL, Boyle R, Gajjar A. Examination of risk factors for intellectual and academic outcomes following treatment for pediatric medulloblastoma. Neuro-Oncology. 2014;16(8):1129–1136. [PMC free article: PMC4096173] [PubMed: 24497405]
• Shevell M, Ashwal S, Donley D, Flint J, Gingold M, Hirtz D, Majnemer A, Noetzel M, Sheth RD. Practice parameter: Evaluation of the child with global developmental delay. Report of the Quality Standards Subcommittee of the American Academy of Neurology and The Practice Committee of the Child Neurology Society. Neurology. 2003;60(3):367–380. [PubMed: 12578916]
• Shiga T, Shimbo T, Yoshizawa A. Multicenter investigation of lifestyle-related diseases and visceral disorders in thalidomide embryopathy at around 50 years of age. Birth Defects Research. Part A, Clinical and Molecular Teratology. 2015;103(9):787–793. [PMC free article: PMC5157726] [PubMed: 26033770]
• Shriberg LD. Four new speech and prosody-voice measures for genetics research and other studies in developmental phonological disorders. Journal of Speech and Hearing Research. 1993;36:105–140. [PubMed: 8450654]
• Shriberg LD, Tomblin JB, McSweeny JL. Prevalence of speech delay in 6-year-old children and comorbidity with language impairment. Journal of Speech, Language, and Hearing Research. 1999;42(6):1461–1481. [PubMed: 10599627]
• Simpson NH, Addis L, Brandler WM, Slonims V, Clark A, Watson J, Scerri TS, Hennessy ER, Bolton PF, Conti-Ramsden G, Fairfax BP, Knight JC, Stein J, Talcott JB, O'Hare A, Baird G, Paracchini S, Fisher SE, Newbury DF. Increased prevalence of sex chromosome aneuploidies in specific language impairment and dyslexia. Developmental Medicine & Child Neurology. 2014;56(4):346–353. [PMC free article: PMC4293460] [PubMed: 24117048]
• Skebo CM, Lewis BA, Freebairn LA, Tag J, Ciesla AA, Stein CM. Reading skills of students with speech sound disorders at three stages of literacy development. Language, Speech, and Hearing Services in Schools. 2013;44(4):360–373. [PMC free article: PMC4393556] [PubMed: 23833280]
• Soleymani Z, Keramati N, Rohani F, Jalaei S. Factors influencing verbal intelligence and spoken language in children with phenylketonuria. Indian Pediatrics. 2015;52(5):397–401. [PubMed: 26061925]
• Spaulding TJ, Szulga MS, Figueroa C. Using norm-referenced tests to determine severity of language impairment in children: Disconnect between U.S. policy makers and test developers. Language, Speech, and Hearing Services in Schools. 2012;43(2):176–190. [PubMed: 22269585]
• Spitz RV, Tallal P, Flax J, Benasich AA. Look Who's Talking: A Prospective Study of Familial Transmission of Language Impairments. Journal of Speech, Language, and Hearing Research. 1997;40(5):990–1001. [PubMed: 9328871]
• Squires J, Twombly E, Bricker D, Potter L. ASQ-3: Ages & Stages Questionnaires. 3rd ed. Baltimore, MD: Paul H. Brookes Publishing Co.; 2009.
• Stanton-Chapman TL, Chapman DA, Kaiser AP, Hancock TB. Cumulative risk and low-income children's language development. Topics in Early Childhood Special Education. 2004;24(4):227–237.
• Stoeckel RE, Colligan RC, Barbaresi WJ, Weaver AL, Killian JM, Katusic SK. Early speech-language impairment and risk for written language disorder: A population-based study. Journal of Developmental & Behavioral Pediatrics. 2013;34(1):38–44. [PMC free article: PMC3546529] [PubMed: 23275057]
• Sun L, Wallach GP. Language disorders are learning disabilities: Challenges on the divergent and diverse paths to language learning disability. Topics in Language Disorders. 2014;34(1):25–38.
• Swarts JD, Bluestone CD. Eustachian tube function in older children and adults with persistent otitis media. International Journal of Pediatric Otorhinolaryngology. 2003;67(8):853–859. [PubMed: 12880664]
• Takahashi H, Takahashi K, Liu FC. Forkhead Transcription Factors: Vital Elements in Biology and Medicine. Maiese K, editor. New York: Springer; 2010. pp. 117–129. (FOXP genes, neural development, speech and language disorders).
• Tedeschi AS, Roizen NJ, Taylor HG, Murray G, Curtis CA, Parikh AS. The prevalence of congenital hearing loss in neonates with Down syndrome. The Journal of Pediatrics. 2015;166(1):168–171. [PubMed: 25444523]
• Tomblin JB. Understanding individual differences in language development across the school years. Tomblin JB, Nippold MA, editors. New York: Psychology Press; 2014. pp. 166–203. (Educational and psychosocial outcomes of language impairment in kindergarten).
• Tomblin JB, Buckwalter PR. Heritability of poor language achievement among twins. Journal of Speech, Language, and Hearing Research. 1998;41(1):188–199. [PubMed: 9493744]
• Tomblin JB, Nippold MA, editors. Understanding individual differences in language development across the school years. New York: Psychology Press; 2014.
• Tomblin JB, Smith E, Zhang X. Epidemiology of specific language impairment: Prenatal and perinatal risk factors. Journal of Communication Disorders. 1997a;30(4):325–344. [PubMed: 9208366]
• Tomblin JB, Records NL, Buckwalter P, Xhang X, Smith E, O'Brien M. Prevalence of specific language impairment in kindergarten children. Journal of Speech, Language, and Hearing Research. 1997b;40(6):1245–1260. [PMC free article: PMC5075245] [PubMed: 9430746]
• Troia GA. Handbook of language and literacy: Development and disorders. 2nd ed. Stone CA, Silliman ER, Ehren BJ, Wallach GP, editors. New York: Guilford Press; 2013. pp. 227–245. (Phonological processing deficits and literacy learning).
• Urbina S. Essentials of behavioral science: Essentials of psychological testing. 2nd ed. Somerset, NJ: Wiley; 2014.
• Viding E, Spinath FM, Price TS, Bishop DV, Dale PS, Plomin R. Genetic and environmental influence on language impairment in 4-year-old same-sex and opposite-sex twins. Journal of Child Psychology and Psychiatry. 2004;45(2):315–325. [PubMed: 14982245]
• Vinchon M, Rekate H, Kulkarni AV. Pediatric hydrocephalus outcomes: A review. Fluids and Barriers of the CNS. 2012;9(1):18. [PMC free article: PMC3584674] [PubMed: 22925451]
• Voci SC, Beitchman JH, Brownlie EB, Wilson B. Social anxiety in late adolescence: The importance of early childhood language impairment. Journal of Anxiety Disorders. 2006;20(7):915–930. [PubMed: 16503112]
• Walker SP, Wachs TD, Grantham-McGregor S, Black MM, Nelson CA, Huffman SL, Baker-Henningham H. Inequality in early childhood: risk and protective factors for early child development. Lancet. 2011;9799(378):1325–1338. [PubMed: 21944375]
• Wallace IF, Berkman ND, Watson LR, Coyne-Beasley T, Wood CT, Cullen K, Lohr KN. Screening for speech and language delay in children 5 years old and younger: A systematic review. Pediatrics. 2015;136(2):e448–e462. [PubMed: 26152671]
• Werker JF, Yeung HH, Yoshida KA. How do infants become experts at native-speech perception? Current Directions in Psychological Science. 2012;21(4):221–226.
• Whitehouse AJO, Shelton WMR, Ing C, Newnham JP. Prenatal, perinatal, and neonatal risk factors for specific language impairment: A prospective pregnancy cohort study. Journal of Speech, Language, and Hearing Research. 2014;57(4):1418–1427. [PubMed: 24686440]
• Wilkinson J, Bass C, Diem S, Gravley A, Harvey L, Maciosek M, McKeon K, Milteer L, Owens J, Rothe P, Snellman L, Solberg L, Vincent P. Institute for Clinical Systems Improvement health care guideline: Preventive services for children and adolescents. 2013. [September 29, 2015]. https://www​.icsi.org​/_asset/x1mnv1/PrevServKids-Interactive0912.pdf.
• WHO (World Health Organization). The ICD-10 classification of mental and behavioral disorders: Clinical descriptions and diagnostic guidelines. Geneva, Switzerland: WHO; 1992.
• Yairi E, Ambrose N. Epidemiology of stuttering: 21st century advances. Journal of Fluency Disorders. 2013;38(2):66–87. [PMC free article: PMC3687212] [PubMed: 23773662]
• Yan J, Oliveira G, Coutinho A, Yang C, Feng J, Katz C, Sram J, Bockholt A, Jones IR, Craddock N, Cook EH Jr., Vicente A, Sommer SS. Analysis of the neuroligin 3 and 4 genes in autism and other neuropsychiatric patients. Molecular Psychiatry. 2005;10(4):329–332. [PubMed: 15622415]
• Young AR, Beitchman JH, Johnson C, Douglas L, Atkinson L, Escobar M, Wilson B. Young adult academic outcomes in a longitudinal sample of early identified language impaired and control children. Journal of Child Psychology and Psychiatry. 2002;43(5):635–645. [PubMed: 12120859]
• Zimmerman FJ, Christakis DA, Meltzoff AN. Associations between media viewing and language development in children under age 2 years. The Journal of Pediatrics. 2007;151(4):364–368. [PubMed: 17889070]