9781405145923_4_047.qxd     11/7/07     1:59 PM    Page 781                                                  Speech and La...
9781405145923_4_047.qxd      11/7/07    1:59 PM    Page 782          CHAPTER 47          diagnosis, including acquired epi...
9781405145923_4_047.qxd     11/7/07    1:59 PM     Page 783             Table 47.1 Language assessments in common use in t...
9781405145923_4_047.qxd      11/7/07    1:59 PM    Page 784          CHAPTER 47          to understand, analysis of the pa...
9781405145923_4_047.qxd    11/7/07    1:59 PM     Page 785                                                                ...
9781405145923_4_047.qxd     11/7/07    1:59 PM    Page 786          CHAPTER 47          by secondary behaviors such as phy...
9781405145923_4_047.qxd    11/7/07    1:59 PM    Page 787                                                                 ...
9781405145923_4_047.qxd      11/7/07     1:59 PM    Page 788          CHAPTER 47          this point, consider how you wou...
9781405145923_4_047.qxd    11/7/07    1:59 PM     Page 789                                                                ...
9781405145923_4_047.qxd       11/7/07     1:59 PM    Page 790          CHAPTER 47          with children varying in terms ...
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9781405145923_4_047.qxd       11/7/07   1:59 PM    Page 792          CHAPTER 47          memory, limited understanding, we...
Speech and language disorders (2008) Bishop & Norbury
Speech and language disorders (2008) Bishop & Norbury
Speech and language disorders (2008) Bishop & Norbury
Speech and language disorders (2008) Bishop & Norbury
Speech and language disorders (2008) Bishop & Norbury
Speech and language disorders (2008) Bishop & Norbury
Speech and language disorders (2008) Bishop & Norbury
Speech and language disorders (2008) Bishop & Norbury
Speech and language disorders (2008) Bishop & Norbury
Speech and language disorders (2008) Bishop & Norbury
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Speech and language disorders (2008) Bishop & Norbury

  1. 1. 9781405145923_4_047.qxd 11/7/07 1:59 PM Page 781 Speech and Language Disorders 47 Dorothy V. M. Bishop and Courtenay Frazier Norbury Speech, Language and Communication are represented by words that are composed of a small set of speech sounds, or phonemes). Where learning of oral language The distinction between speech, language and communica- is compromised because a child is deaf, manual (sign) languages tion may be illustrated by three child cases. Emma is a lively have evolved, showing similar structural characteristics to and engaging 9-year-old who has difficulty making herself spoken languages. In addition, oral language can be expressed understood because her production of speech sounds is very in written form. Language involves more than speech, and com- unclear. However, she demonstrates normal language skills: munication involves more than language. However, it is she understands what others say to her, and can express her- possible for someone to speak without producing language self in writing using long and complex sentences. Her ability (e.g., when a person utters meaningless gobbledegook), and to communicate is hampered by her speech difficulties, but she it is possible for someone to produce utterances that obey the enjoys interacting with others, and when people fail to under- formal rules of language, yet communication is not achieved, stand her, she supplements her utterances with gesture and facial as in the case of Jack. In evaluating children with impairments, expression to get her message across. it is important to keep these three levels in mind, and to recog- Thomas is a 6-year-old who has no difficulty in producing nize that a problem at one level does not necessarily entail a speech sounds clearly, but his language skills are limited, as problem at another. evidenced by his use of simple and immature sentence con- In this chapter we make a broad division between disorders struction. Instead of saying “I’d like a drink” he says “Me affecting speech, and those affecting language and communica- want drink.” However, although his language is far more tion. This distinction has some similarity with the distinction simple than that of other 6-year-olds, he does use it to com- made in DSM-IV-TR (American Psychiatric Association, 2000) municate with other children and adults. In contrast, 4-year- between phonological disorder (315.39) and language disorder old Jack produces a great deal of complex, fluent and clearly (315.31), but the coverage is broader. Among speech disorders, articulated language, but he does not use it to communicate we cover disorders affecting fluency, voice and prosody as effectively. Thus, his opening gambit to a stranger might be well as problems of speech sound production that may have to say: “In Deep Space Nine you can’t get to level 6 until you a neurological basis. For language and communication dis- have killed all the foot soldiers, but if you get to level 6, you orders, we focus heavily on specific language impairment (SLI), have to first destroy the klingons before you can enter the palace which is analogous to the DSM language disorder category, of death.” but we also consider other conditions required for a differential One way of depicting the relationship between speech, language and communication is shown in Fig. 47.1, where language is a subset of communication and speech is a subset of language. Communication is defined by McArthur (1992, p. 238) as “the transmission of information (a message) between a source and a receiver, using a signaling system.” The primary means of communication between humans is Speech through language, but communication also encompasses other means of signaling meaning, such as facial expression, bodily gesture and non-verbal sounds. Language differs from these other communicative modes; it is a complex formal system in Language which a small number of elements are combined in a rule-based manner to generate an infinite number of possible meanings. Most human language is expressed in speech (i.e., meanings Communication Rutter’s Child and Adolescent Psychiatry, 5th edition. Edited by M. Rutter, D. Bishop, D. Pine, S. Scott, J. Stevenson, E. Taylor and A. Fig. 47.1 Relationship between speech, language and Thapar. © 2008 Blackwell Publishing, ISBN: 978-1-4051-4592-3. communication. 781
  2. 2. 9781405145923_4_047.qxd 11/7/07 1:59 PM Page 782 CHAPTER 47 diagnosis, including acquired epileptic aphasia, autistic disorder During these informal tasks, the practitioner can make a num- and selective mutism. ber of important observations. The first concerns the child’s expressive language output. How long and grammatically complex are the child’s utterances? How rich is the child’s General Principles of Assessment vocabulary? Does he or she struggle to find the words for com- mon objects? Does he or she use gestures and facial expres- In most instances, detailed assessment of the speech and sion? Is the speech fluent, or is the child’s speech peppered language system will be carried out by a specialist speech- with hesitations and repetitions? What is the child’s voice language therapist, who will have extensive knowledge of quality like? Is he or she shouting and hoarse, or whispering linguistics and language development, the anatomy and physio- inappropriately? Is the child intelligible, or are there numer- logy that supports the language system, and access to a variety ous speech errors that impede understanding? Does the child of assessment and intervention techniques. With regard to tell a story as a coherent sequence of events, or does he or communication, the primary decisions for the practitioner to she get muddled and leave important events out? make at initial assessment are: The next set of observations concerns the child’s under- 1 Is the child’s communication development delayed or standing, which may be more difficult to gauge in this setting. disordered? Nevertheless, it can be revealing to observe how the child 2 What aspects of communication are causing the most concern? responds to the questions and comments of others. Are the 3 Is referral to speech-language therapy warranted? answers appropriate to the questions? Does the child follow The first port of call in the assessment process is the case adult directions? Does the child understand the premise of a history. This will give the practitioner an opportunity to story or does he or she misinterpret key events? Does the child explore with the child’s parents who is concerned about com- appear to understand the gestures and facial expressions of munication, and precisely what they are concerned about. others? Can the child listen while engaged with something else, Although many parents will be concerned about the child’s or must the adult focus his or her attention before speaking? language development, others may not be aware of difficul- Finally, these informal interactions enable the practitioner ties with communication. These parents may not see language to observe other important behaviors. How and why does the as the central problem, but will voice concerns about behavior, child engage with the other people in the room? Does he or social skills and learning that may be related to underlying she look up when called? Is the child’s play creative and imag- language difficulties. inative, or destructive and repetitive? Can the child stick with As part of the case history, it is essential to obtain from an activity, or is his or her attention span unduly short? Is the parents clear examples of what motivates the child to com- child frustrated when he or she is not understood? Does he municate and how the child achieves communication. For or she try again? Does the child recognize when he or she has example, does the child communicate only to get his or her not understood something and ask for clarification? Is the child basic needs met? Does the child communicate to show others anxious, or does he or she quickly adjust to the new situation? things that interest him or her? Does the child use words or In combination with the case history, this set of observations phrases? If not, does the child gesture, vocalize and/or point should provide the practitioner with a working hypothesis of in an effort to get the message across? In addition to concrete the child’s strengths and weaknesses which will guide the assess- examples of the types of communication the child produces, it is also important to ascertain the types of communication ment process (see chapter 19). ! the child can understand. Does the child follow an adult’s point or eye gaze? Can he or she follow simple verbal instructions Speech Disorders out of context? For more able children this may not pose a problem, but they may have difficulty following a story or Speech refers to the production of oral language, which is getting the point of a joke. achieved by modifications to the vocal tract while a stream Once the practitioner has gained an impression of the child of air is breathed out from the lungs. Speech difficulties in from the parents, it will be necessary to determine directly the children are not difficult to detect, but accurate diagnosis child’s current level of functioning. Throughout the rest of this requires specialist assessment by a speech and language ther- chapter, we give specific signposts to impairment in speech, apist. The main types of difficulty that are encountered are language and broader communication, and suggest standard- those affecting the distinctive production of speech sounds, ized assessments in each of these domains that can assist in fluency of connected speech, voice, and prosody (i.e., speech the diagnostic process (Table 47.1). However, it is usually melody and intonation). preferable to start by observing the child’s communication in a less structured setting. This can be achieved by videoing the Differential Diagnosis of Speech Sound Disorders child playing with his or her parents or siblings in the clinic. All spoken languages encode meaning in terms of a small set If the child has some verbal language, this play session can of vowels and consonants: in standard British English there be supplemented by asking the child to recall a favorite story, are 24 consonants and 20 vowels that can be combined to computer game or television program. yield thousands of words. When a child’s speech is difficult 782
  3. 3. 9781405145923_4_047.qxd 11/7/07 1:59 PM Page 783 Table 47.1 Language assessments in common use in the UK. Assessment Age range Description Phonology Goldman–Fristoe Test of Articulation–2 2–21 years Naming task which samples all consonants and clusters of English in (Goldman & Fristoe, 2000) initial, medial and final word positions. Assesses spontaneous and imitated speech Diagnostic Evaluation of Articulation and Phonology 3–6 years Picture materials elicit speech with goal of differentiating between (DEAP) (Dodd et al., 2002) articulation problems, delayed phonology and consistent versus inconsistent phonological disorder Phonological Assessment Battery (PhAB) 6–14 years Tests of phonological processing: alliteration, naming speed, rhyme, (Frederickson et al., 1997) spoonerisms, fluency and non-word reading Children’s Test of Non-word Repetition 4–8 years A measure of phonological short-term memory; the child listens to (Gathercole & Baddeley, 1996) non-words and repeats them Semantics MacArthur–Bates Communicative Development 8–30 months Parent reports of words child understands and produces early @ Inventories (Fenson et al., 1994, 2003) British Picture Vocabulary Scales–2 3–15 years communicative gestures and early word combinations Understanding of single words. Child matches spoken word to one of (Dunn et al., 1998) four pictures Expressive/Receptive One Word Picture Vocabulary 2–12 years Child either names a picture (expressive) or matches a spoken word Tests (Gardner, 2000) to one of four pictures Test of Word Knowledge (ToWK) 5–17 years Expressive and receptive semantics including definitions, antonyms, (Wiig & Secord, 1992) synonyms, multiple meanings Syntax Renfrew Action Picture Test (RAPT) 3–8 years Sentence elicitation task in which children describe what is happening (Renfrew, 1988) in 10 different pictures. Scored for information content and syntactic complexity Test for Reception of Grammar–2 (TROG-2) 4 years–adult Child matches spoken sentence to one of four pictures. Assesses (Bishop, 2003b) range of grammatical structures Narrative The Bus Story (Renfrew, 1988) 3–8 years Provides age equivalent scores for story information and sentence complexity Expression, Reception and Recall of Narrative 6 years–adult Narrative assessment that provides standard scores for information Instrument (ERRNI) (Bishop, 2004) content, complexity of grammatical structure, comprehension of pictured story, recall of narrative Pragmatics Children’s Communication Checklist–2 (CCC-2) 4–16 years Parental report of language and pragmatic behaviors in everyday (Bishop, 2003a) situations. Provides standard scores Omnibus tests Assessment of Comprehension and Expression 6–11 years Assesses sentence comprehension, inferencing, naming, formulating (ACE) (Adams et al., 2001) sentences, semantics, non-literal language comprehension, narrative Clinical Evaluation of Language Fundamentals– 3–6 years; Assesses basic concepts, syntax, morphology, semantics, verbal Preschool (Wiig et al., 1992) and Clinical 5 years–adult memory. Provides receptive and expressive as well as total language Evaluation of Language Fundamentals (Semel score et al., 2003) Pre-school Language Scales–3 (Zimmerman et al., Birth-6 years Assesses listening comprehension, expressive communication and 1997) provides a total language score Reynell Developmental Language Scales–3 1–7 years Measures receptive language (verbal and non-verbal) and expressive (Edwards et al., 1997) language, including structure and vocabulary Test of Language Competence (Wiig & Secord, 9–18 years Assesses higher level language skills such as inferencing, multiple 1989) meanings, figurative language, sentence production in conversational contexts Test of Language Development–3 (TOLD-3) 4–12 years Subtests measure both semantic knowledge and grammar (Newcomer & Hammill, 1997) 783
  4. 4. 9781405145923_4_047.qxd 11/7/07 1:59 PM Page 784 CHAPTER 47 to understand, analysis of the pattern of errors will be help- a disorder of planning movement sequences that is not ac- ful in distinguishing whether the difficulty is the result of a counted for in terms of lower-level difficulties in executing structural or motor impairment affecting the articulatory individual movements. However, it is unclear whether motor apparatus (i.e., a dysarthria) or whether other explanations programing is at the root of the inconsistent speech difficulties need to be sought (Dodd, 2005). Usually, dysarthria will be seen in children. Individuals with the clinical picture of devel- accompanied by other evidence of physical or neurological opmental verbal dyspraxia often have major problems in per- impairment, and the production of speech sounds will be dis- ception as well as production of speech sounds, doing poorly torted or labored. on tests that require them to discriminate or classify sounds (Stackhouse & Wells, 1997). Some experts argue that devel- Phonological Disorder opmental verbal dyspraxia is simply an unusually severe kind Contrary to popular belief, most childhood problems with of phonological disorder in children, reflecting an underlying speech production do not have a physical basis. For many years difficulty learning the categorization of speech sounds, rather there was a belief that children’s speech difficulties could be than having motor origins. The jury is still out on this ques- caused by “tongue tie,” which could be cured by cutting the tion, not least because different experts use different diagnostic frenum. However, surgery is seldom effective in improving criteria (Forrest, 2003). speech and it is now recognized that interventions that train One way of bypassing diagnostic difficulties has been to children to perceive and produce sounds accurately are more use the more general term “speech sound disorder” (SSD) to effective. The key point to note is that speech production encompass all difficulties of speech sound production in chil- involves more than articulation: in learning a language, the dren that do not have a physical basis, without needing to child has to integrate speech perception with production, and specify whether they are motor-based or phonological in ori- work out which sounds in the language are used to signal con- gin. Although such “lumping” of disorders might seem likely trasts in meaning (i.e., correspond to phonemes). To illustrate to obscure important differences between phenotypes, Lewis the difference between articulation and phonology, consider et al. (2004) argued in its favor. They compared family pedi- the following: many native English-speakers have great dif- grees of children with verbal dyspraxia and children with other ficulty in correctly learning to produce the French words forms of SSD. Verbal dyspraxia showed very high familiality, “rue” and “roux” distinctively. This is because the vowel con- but the disorder did not “breed true,” and affected relatives trast in these words does not match the phonemes in English, were more likely to have other forms of SSD or language impair- where there is just one “oo” sound. This has nothing to do ment than to have verbal dyspraxia themselves. Lewis et al. with the structure of the articulatory apparatus, and every- (2004) concluded that the principal difference between chil- thing to do with perceptual experience of a language, which dren with verbal dyspraxia and those with other SSD was in leads English-speakers to treat all instances of “oo” as one the degree of genetic loading for disorder. phoneme, where French-speakers divide the vowel space into two phonemes. Most cases of childhood speech production Assessment of Speech Sound Disorders difficulties appear analogous to the problems of the second Coplan and Gleason (1988) provided guidelines to help health language-learner: they arise because the child has not learned professionals decide when to refer a child for speech assess- to categorize speech sounds appropriately, and so may fail to ment, based on a parent’s response to the question, “How much differentiate sounds that are important for signaling contrasts of your child’s speech can a stranger understand?” At 2 years, in meaning. Over the years, a variety of terminology has been referral should be considered if the child is less than 50% intel- used to describe such difficulties, including functional articu- ligible, at 3 years if less than 75% and at 4 years if less than lation disorder and phonological disorder/impairment. 100% intelligible. Referral to a speech-language therapist is strongly recommended when poor speech intelligibility occurs Developmental Verbal Dyspraxia Sitting somewhat uneasily between dysarthria on the one in combination with other risk factors (see p. 000). Assessment by the speech-language therapist will involve ex- # hand, and phonological disorder on the other is the category amination of the articulatory apparatus. A history of difficulty of developmental verbal dyspraxia, also known as develop- with sucking, chewing, dribbling, licking or blowing should mental apraxia of speech. An early use of the term was by alert the clinician to the possibility of physical impairment, Morley (1957), who applied it to children in whom the neuro- such as submucous cleft palate, or neurological impairment. muscular control of the articulators seemed adequate for all Where there is facial dysmorphology or evidence of neurological purposes except the rapid integrated movements used in speech. dysfunction, referral to specialist medical services (pediatric Such children might be able to imitate accurately a simple neurology, otolaryngology or clinical genetics) is warranted. syllable or word, but would make errors if asked to produce The speech-language therapist will construct a phonemic longer words or connected sentences. Stackhouse and Wells inventory of sounds the child is able to produce and will look (1997) noted that production of longer words may be incon- for inconsistency of word pronunciations and the presence sistent as well as inaccurate, so that “caterpillar” could be pro- of “phonological processes” (i.e., consistent error patterns), duced as “capertillar,” “taperkiller” or “takerpillar.” The term such as replacing /k/ with /t/ so that “cat” becomes “tat” and “dyspraxia” is taken from adult neurology where it describes “take” becomes “tate.” Many of these processes are seen in 784
  5. 5. 9781405145923_4_047.qxd 11/7/07 1:59 PM Page 785 SPEECH AND LANGUAGE DISORDERS the course of normal phonological development; however, an limited to one report of linkage to a site on chromosome 3 SSD is diagnosed when such processes continue beyond the (Stein et al., 2004). normal age, or when there are numerous inconsistencies and atypical phonological processes. Intervention and Prognosis for Speech “Phonological processing” is a general term used to cover Sound Disorders more subtle difficulties in using phonological information. A variety of techniques may be employed to improve speech Phonological awareness in particular is nowadays often tar- intelligibility, and research to date suggests that no single geted in assessment as research has demonstrated links with later treatment approach is appropriate for all children with SSD literacy difficulties (Snowling & Stackhouse, 2006). This refers (Dodd & Bradford, 2000). Techniques might include using to the ability to manipulate the sound segments in the language tactile and visual cues to enable children to produce the target and includes tasks such as rhyming, segmenting syllables and sound accurately. This will be combined with repeated practice phonemes in words, identifying initial and final word sounds, at producing the target sound in words with corrective feed- and deleting, adding or transposing phonemes in words. back. More meta-linguistic approaches involve games and Such problems can been seen in children with normal speech exercises to develop the child’s awareness of meaningful phon- sound production but are often also seen in children with SSD, emic contrasts (Gierut, 1998). suggesting their difficulties do not involve the physical act In a recent meta-analysis of the literature, Law, Garrett, and of articulating speech, but rather the ability to perceive and Nye (2004) found that phonological interventions were gen- categorize different exemplars of the same phoneme (Bird, erally effective when compared with no treatment. The most $ Bishop, & Freeman, 1995; Stackhouse & Wells, 2006). An important point to stress is that although speech and effective treatments were those carried out by speech-language therapists, rather than parent-administered treatments, and those language difficulties are not the same thing, they do often co- that lasted for longer than 8 weeks. Therapist-led treatments occur. We therefore recommend that any child who presents may incorporate a variety of techniques, such as “articulation with a speech difficulty should have a full assessment of both drills” in which the child learns and practises correct produc- speech and language. tion of speech sounds with visual aids such as cued articula- tion (hand gestures that illustrate the place and manner of Prevalence, Causes and Correlates of Speech articulation) or symbols (pictures of place and manner of Sound Disorders articulation). Other techniques (e.g., Metaphon) emphasize a Estimates of prevalence of SSD are hampered by inconsist- meta-linguistic approach to improving speech production encies in diagnostic criteria. Gierut (1998) cited a 1994 report (Howell, & Dean, 1994). This treatment teaches sound “con- from the US National Institute on Deafness and Other Com- cepts” so that children learn, for example, the differences munication Disorders which estimated that phonological between “short” sounds (/t/ and /d/) and “long” sounds (/s/ and disorders affected approximately 10% of preschool and /f/). The therapy also utilizes “meaningful minimal contrasts,” school-aged children, and that in 80% of cases the disorder in which the child is required to alter speech production to was severe enough to merit clinical treatment. At 6 years of avoid ambiguity. For instance, if the child is “fronting” (pro- age, the prevalence of “speech delay” was estimated at 3.8% in ducing /k/ sounds as /t/ sounds), the therapist might construct a US epidemiological study (Shriberg, Tomblin, & McSweeny, a game in which the child has to ask for a “key” or “tea.” If 1999). the child intends to ask for the “key” but the therapist Campbell et al. (2003) identified a number of factors that responds with the “tea,” the child is forced to adapt his pro- greatly increased the risk of speech sound disorders in pre- nunciation to convey his or her intended meaning. Many ther- school children. These included male gender, limited maternal apists will use a combination of techniques depending on the education and a positive family history of speech and language needs of the child, as there is currently no evidence that one disorder. These authors also suggested that an accumulation method of treatment is more effective than any other method. of risk factors exerted a greater threat to developmental The longer term prognosis for children with isolated pho- outcome than individual risks. Children with only one risk nological impairments is much better than that of language factor were 1.7–2.6 times more likely than children who had impairment, especially if the phonological difficulties resolve none of these characteristics to have speech delay at 3 years; by the time the child starts school. However, the child who children with all three risk factors present were almost eight starts school with phonological difficulties is at increased risk times more likely to have speech delay at 3 years. of long-lasting literacy deficits (Stothard, Snowling, Bishop, Both family (Lewis et al., 2004) and twin studies (Bishop, Chipchase, & Kaplan, 1998). 2002; DeThorne et al., 2006) suggest a strong genetic etiology for SSD. Although verbal dyspraxia can follow an autosomal Other Types of Speech Disorder dominant pattern of inheritance in some families (Hurst, Fluency Disorders Baraitser, Auger, Graham, & Norell, 1990), in most cases there Stuttering and stammering are two popular terms for dys- are numerous genes that contribute to risk of poor speech fluent speech. Developmental dysfluency is characterized by and language skills, rather than a single genetic mutation. To involuntary repetitions, blocks or prolongations of sounds, date, progress in the search for a molecular basis has been syllables and words in discourse. These may be accompanied 785
  6. 6. 9781405145923_4_047.qxd 11/7/07 1:59 PM Page 786 CHAPTER 47 by secondary behaviors such as physical tension in the speech These features can have profound effects on how a child is musculature, eye blinking or breaking of eye contact, move- perceived by others and adversely affect socialization. ments of the head and limbs, and emotional reactions to the Recent prevalence estimates from a population-based study dysfluency, including anxiety and avoidance of speaking. suggest 6–11% of school-aged children present with dyspho- Persistent dysfluency is estimated to affect 1% of the popu- nia (Carding, Roulsone, Northstone, & Team, 2006). This lation (Yairi & Ambrose, 1999), although many more children is considerably higher than would be predicted from clinical produce normal dysfluencies during the preschool years. Like referrals, but this probably reflects widespread lack of recog- many speech, language and communication disorders, it ap- nition of the problem (Boyle, 2000). Gender (male) and older pears to be strongly familial, and more boys are affected more siblings were the most significant risk factors in the Carding often than girls (ratio of 1.65:1; Mansson, 2000). Campbell, et al. study. Campbell et al. (2002) reported unpublished data Dollaghan, and Yaruss (2002) suggest referral to a speech- from their own sample of 427 clinical referrals to a specialist language therapist if parents report: clinic; 93% of these children had abnormal voice quality 1 Frequent part-word dysfluencies; associated with laryngeal pathology. The most common patho- 2 Noticeable physical tension or struggle; logy was vocal nodules (i.e., mechanical trauma caused by one 3 Any sign that the child is frustrated or concerned about vocal fold making excessive contact with the other). Surgical talking; or treatment is not recommended in such cases, as nodules are 4 Concerns about any other aspect of speech and language likely to return if damaging vocal behavior is not altered. development. Behavioral treatments can be effective and center on modify- The etiology of childhood stuttering appears to be multi- ing the environment (i.e., reducing competing noise) and factorial, with a significant genetic component (Yairi, Ambrose, training the child to use the voice more appropriately. & Cox, 1996). An international study by Suresh et al. (2006) suggested a complex etiology, with the strongest linkages being Prosodic Disorders found when separate analyses were conducted for males (link- Prosody may be defined as the suprasegmental properties age to chromosome 7, LOD score 2.99) and females (linkage of the speech signal that modulate and enhance its meaning to chromosome 21, LOD score 4.5), and when interactions between sites on different chromosomes were considered. (Paul et al., 2005). Prosody includes variations in pitch, loud- ness, duration, rhythm, tempo and pausing, and serves a wide % Stuttering has been associated with early difficulties in lan- range of grammatical, pragmatic and affective functions. For guage formulation (Bloodstein, 2006) and atypical develop- example, variations in stress and intonation may signal the ment of the auditory temporal cortex (Foundas et al., 2004). difference between a noun (con vict) and a verb (con vict), Furthermore, comorbidity with speech sound disorders is 30% highlight elements within the sentence for attentional focus (the (Yairi & Ambrose, 1999). Therefore, assessment of broader blue book, as opposed to the red one), and convey a speaker’s speech and language abilities is warranted. emotional state. Approximately 75% of preschoolers will recover from It is frequently reported that impaired prosody is charac- dysfluency without professional involvement (Yairi & Ambrose, teristic of verbal individuals with autistic spectrum disorder 1999). However, prognosis is poor for those who continue to stutter beyond the age of 7 years (Campbell et al., 2002). There (ASD), although it may not be universal. Paul et al. (2005) reported that 47% of the 30 adolescent and adult speakers ^ is considerable debate regarding the most appropriate form with ASD they investigated had prosodic abnormalities. Such of intervention. One approach, exemplified by the Michael Palin abnormalities have a negative effect on how listeners perceive Centre for stammering in London (www.stammeringcentre. social and communicative competence and pose significant org), focuses on modifying the environment to reduce speak- ing pressure and working with children and families to reduce obstacles to social integration and employment (Paul et al., 2005). & anxiety about speaking (for full description see Rustin, Cook, Botterill, Hughes, & Kelman, 2001). An alternative approach, Disorders of Language and exemplified by the Lidcombe Programme (http://www3.fhs. Communication usyd.edu.au/asrcwww/treatment/lidcombe.htm), provides direct behavioral modification to reinforce fluent speech. There are Components of Language few, if any, methodologically sound investigations of treatment Competent adults produce language so effortlessly that it is efficacy and no studies that we are aware of that explicitly easy to forget just what a complex system it is. All spoken compare the two treatment approaches. However, there is some languages can be studied in terms of four levels of descrip- preliminary evidence that behavioral approaches are effective tion: phonology (speech sounds); semantics (meaning); gram- in reducing dysfluent speech in the preschool years (Jones et mar (formal ways of using word order and inflection); and al., 2005). pragmatics (use of language to communicate). However, there is considerable variation from one language to another at all Voice Disorders of these levels. For instance, Chinese does not have word in- A voice disorder, dysphonia, should be suspected when a flections, whereas Turkish has numerous inflections that are child speaks with abnormal pitch, loudness and/or hoarseness. appended to word stems in an agglutinative fashion. Clearly, 786
  7. 7. 9781405145923_4_047.qxd 11/7/07 1:59 PM Page 787 SPEECH AND LANGUAGE DISORDERS the task confronting the young language learner is going to genetic risk factors operate for children with language diffi- be very different in these two languages, and in English, culties regardless of their non-verbal IQ (Bishop, 1994). Thus, which uses inflections, but much more sparsely than many other the logic of distinguishing between children who do and do not languages. As well as the different levels of linguistic repres- meet strict IQ discrepancy criteria is questionable. entation, language can be divided into expressive (production) and receptive (comprehension) aspects. To be a competent com- Auditory Problems municator, the child must learn to recognize and produce Hearing should always be assessed by an audiologist in a the distinctive speech sounds in the language (the phonology), child who presents with language impairment. As neonatal establish a “mental lexicon” containing representations of words screening programs become more widespread, it is unusual to as phoneme sequences linked to meanings, master the gram- find an undetected sensorineural hearing loss in a language- matical structure of the ambient language, and learn how to impaired child, but one needs to be alert to the possibility select a message to convey meanings economically and effect- of screening errors or a progressive hearing loss. Hearing ively to others (pragmatics). Furthermore, language processing loss restricted to a specific frequency range is easy to miss, has to be carried out at speed. because the child appears responsive to sound, yet crucial in- formation may be lost from the speech signal, leading to a pro- Differential Diagnosis of Specific Language file of impaired language development that may look similar Impairment to SLI (Stelmachowicz, Pittman, Hoover, Lewis, & Moeller, When a child presents with language impairment, the clini- 2004). cian needs to establish whether there is any causal factor It is much more common to find conductive losses in present that could explain the language difficulty, or whether young children with language impairments. However, it is not the language impairment is part of a recognized syndrome. easy to know how to interpret these. Early studies suggested The majority of cases of language impairment in children unusually high rates of language and literacy problems in have no obvious cause (Shevell, Majnemer, Rosenbaum, & children who had otitis media with effusion (OME; Holm Abrhamowicz, 2000), and occur in the context of otherwise & Kunze, 1969). OME typically causes a conductive loss of normal development. This is known as specific language up to 40 dB, and it seems plausible that such a loss might impairment (SLI) and also as primary language impairment, assume significance in a child in the early stages of language developmental language disorder or developmental dysphasia. learning. However, more recent epidemiological studies have Before considering the characteristics of SLI we briefly discuss questioned whether OME is a major etiological factor in other conditions that need to be considered when making a language impairment (Feldman et al., 2003). A substantial differential diagnosis. number of children under 5 years of age have undetected and asymptomatic middle ear disease, particularly in the winter Low Non-verbal Ability months. Prospective studies of children with and without An early step in the assessment of a language-impaired child prolonged episodes of OME have found little or no impact is administration of a non-verbal IQ test. Cases of intellectual on verbal skills, suggesting that language development is disability (non-verbal IQ more than 2 SD below average) are resilient in the face of the mild associated hearing losses. OME * usually straightforward enough to identify (see chapter 49). However, there are many children with slow language devel- may assume more importance if it is chronic and persistent (Feldman et al., 2003). However, we would recommend cau- opment who do not have a syndrome of intellectual disab- tion in assuming that OME is the main causal factor if it is ility, but nevertheless have below-average non-verbal IQ. detected in a child with language impairment. Traditional definitions of SLI usually require that non-verbal There is a large body of knowledge on assessment of the IQ is broadly within normal limits. More stringent definitions integrity of the peripheral auditory pathways in children, but also require there should be a significant mismatch between much less agreement concerning diagnosis of central auditory language ability and non-verbal IQ (equivalent to 1 SD in ICD- processing deficits. In some countries, notably the USA and 10). However, there is increasing disquiet about the use of Australia, the diagnosis of auditory processing disorder (APD IQ discrepancy criteria, because these exclude large numbers – sometimes prefixed with C for central) is frequently made. of children who are not intellectually impaired and yet have However, it is far less common in the UK. The principal evident language difficulties. For instance, if we require there difficulty with the APD concept is that it is typically diagnosed to be a 1 SD difference between a language and non-verbal using tests that use verbal materials (e.g., listening to speech index, then we would exclude a child with a language level in noise) or being presented with two streams of speech in 2 SD below the mean and a non-verbal score 1.3 SD below different ears (Moore, 2006). These tests have demonstrated the mean. This child would not meet criteria for intellectual validity when used to identify central auditory lesions in adults disability and so would be left in a diagnostic limbo and may with acquired brain damage, who can be assumed to have be denied access to intervention, even though the profile and normal language abilities. However, their interpretation is severity of language difficulty may be similar to that seen in complicated in children, because it is difficult to distinguish a child who does meet the discrepancy criterion (Tomblin poor performance resulting from a primary language problem & Zhang, 1999). Furthermore, twin studies suggest the same from a genuine auditory difficulty (Rosen, 2005). To illustrate 787
  8. 8. 9781405145923_4_047.qxd 11/7/07 1:59 PM Page 788 CHAPTER 47 this point, consider how you would fare if you were asked substantial receptive language deficits may persist to adulthood. to carry out a range of listening tests presented in a language Our recommendation is that any child with language regres- with which you had limited competence. It is likely that under sion accompanied by comprehension problems should be optimal listening conditions you would do much better than referred to a pediatric neurologist for an evaluation of AEA. when words were presented in noise or in a competing speech Deonna and Roulet-Perez (2005) note that pharmacological situation. This is because a competent speaker of a language interventions can be effective, but there is wide variation in does not simply decode speech by bottom-up analysis of the responsiveness to treatment, and in the absence of controlled speech signal; he or she also employs top-down processing to clinical trials it is difficult to give precise guidelines. Deonna predict and fill in information. If one uses speech-based tests in diagnosis, then one is likely to end up finding numerous (2000) recommends that when receptive language difficulties persist for more than a few weeks or months, it is crucial !! cases of language impairment that appear to be caused by APD, to provide the child with an alternative mode of communica- but where the problem may in fact arise for quite different tion. Sign language can be effective and does not interfere reasons. In our experience, many children who receive a with attempts to retrain comprehension of auditory language diagnosis of APD from an audiologist would be given a diag- (Roulet-Perez et al., 2001). nosis of SLI, dyslexia, attention deficit/hyperactivity disorder (ADHD) or autistic disorder if seen by a speech and language Delayed Language Development: Late-Talkers therapist, psychologist or child psychiatrist (Dawes & Bishop, When diagnosing SLI, it is important to determine when a ( in preparation). In emphasizing these assessment difficulties, we do not young child’s language delay represents a significant departure from normal variation, which can be difficult when the child wish to imply that APD is not a valid category; it is plausible is younger than 3 years old. Late-talkers are identified as that some children have immature or dysfunctional develop- having severely restricted vocabulary at age 2 years (fewer than ment of the central auditory pathways and this might well 50 words). It is unclear how many late-talkers have similarly impact on language development. However, our concern is impaired receptive language skills, because many studies that APD is often diagnosed using instruments of question- include only children with normal comprehension (Rescorla, able validity, leading to implementation of auditory-based 2005). Many late-talkers meet typical exclusionary criteria interventions that may not be justified. It is vital to adopt an for SLI such as normal non-verbal ability and no hearing interdisciplinary approach, whereby audiologists work together loss; however, most late-talking 2-year-olds will normalize with other professionals to ensure that children receive language function by the time they enter school (Rescorla, appropriate diagnoses and intervention. It is hoped that as 2005), whereas the long-term prognosis for school-aged chil- research on APD advances, better assessment methods, using dren with SLI is less optimistic (Stothard et al., 1998). more objective electrophysiological as well as non-verbal Dale, Price, Bishop, and Plomin (2003) followed a large behavioral tests (Liasis et al., 2003) will give a clearer picture. sample of twins from 2 to 4 years of age. Late-talkers were identified as those 2-year-olds with expressive vocabulary Acquired Epileptic Aphasia scores in the bottom 10th centile (15 words or fewer on a Acquired epileptic aphasia (AEA), also known as Landau– modified version of the MacArthur Communicative Develop- Kleffner syndrome, is a rare cause of childhood language impair- ment Inventory). By age 4, 60% had age-appropriate scores ment which is often misdiagnosed. The typical presentation on parent-report measures of vocabulary, grammar and use is one of deterioration in language skills in the preschool of abstract language. years after a period of normal development. Because the child It appears that gains in language skill are maintained over previously spoke normally, the disorder may be misdiagnosed time. Paul (2000) reported that 84% of late-talkers in her cohort !) as selective mutism (see p. 000); however, in AEA, there is genuine loss of language skills, with comprehension problems had language scores within the normal range at age 7. Rescorla (2005) followed 28 late-talkers from preschool to age predominating. Deafness is usually suspected but ruled out 13 and found that, at this age, all of the children scored within on the basis of a hearing test. Many children with AEA have the normal range on standard measures of language and relatively selective problems with language in the context of literacy. However, their scores were significantly lower than preserved non-verbal ability, but in some children there are a comparison group of typically developing children matched associated behavioral disturbances, which further complicate for socioeconomic status (cf. Stothard et al., 1998). Rescorla the diagnosis (Deonna & Roulet Perez, 2005). The epileptic argued that late-talkers represent a subgroup of SLI charac- manifestations of AEA are not obvious, because overt seizures terized by less severe language weakness. are uncommon, and it may be necessary to carry out a sleep Although 60–85% of late-talking children will improve electroencephalogram (EEG) to demonstrate EEG abnormal- without direct intervention, a minority will not (Paul, 2000; ities. These can be marked, and there has been debate as to Dale et al., 2003). It is not currently possible to distinguish how far this disorder overlaps with slow wave status epilep- reliably between those children with transient and persistent ticus in sleep (SWSS). Some children, particularly those with impairments. Dale et al. (2003) found that severity of lan- onset after 6 years of age, can make a good recovery, but the guage delay at age 2 did not predict language status at age 4. prognosis for those with preschool onset is often poor and In addition, neither gender nor level of maternal education 788
  9. 9. 9781405145923_4_047.qxd 11/7/07 1:59 PM Page 789 SPEECH AND LANGUAGE DISORDERS significantly predicted group outcome. Paul (2000) reported appropriate scores on tests of expressive language or simple that children with persistent language difficulties tended to have vocabulary measures. However, such measures may overest- lower non-verbal abilities, although scores on non-verbal imate true language ability (Mottron, 2004) and the same assessments were still within the normal range and there was children usually have significant comprehension deficits in less considerable overlap between groups with good and poor out- structured and more naturalistic discourse settings (Adams, come. In addition, high socioeconomic status and prosocial Green, Gilchrist, & Cox, 2002). adaptive communicative behaviors were associated with good Textbook cases of autistic disorder and SLI are relatively outcome at age 7. A much smaller scale study by Thal, Tobias, easy to differentiate, but many children present with a pattern and Morrison (1991) indicated that poor receptive language of symptoms that does not fit unambiguously in either category, skills and failure to use gesture were associated with persist- while showing some features of both. Thus, their difficulties ing language difficulties. extend beyond the characteristic grammatical deficits seen Given these findings, a dilemma facing practitioners is what in SLI, but they do not have the full triad of impairments to do when language delay is identified during the preschool in severe enough form to warrant a diagnosis of autism. years. Conventional wisdom posits that early intervention Differentiation between the two disorders may be hampered is desirable, but Paul (2000) questioned the ethics of treating by a changing clinical picture over time (Charman et al., 2005, children who are otherwise developing normally, have normal Mawhood, Howlin, & Rutter, 2000). Conti-Ramsden, Simkin, language comprehension and do not present with any addi- and Botting (2006) applied standard diagnostic instruments tional risk factors for a language “disorder” that they may (Autism Diagnostic Interview – Revised; Lord, Rutter, & overcome naturally without any professional help. Instead, she advocates initial parent training to optimize language input Couteur, 1994; Autism Diagnostic Observation Schedule – Generic; Lord et al., 2000) to 76 adolescents with a history !@ in conjunction with careful monitoring of language development. of SLI, none of whom had been regarded as autistic in Even though good language outcomes are often seen in late- middle childhood. The majority of individuals did not meet talkers, there is evidence to suggest they should be monitored criteria on either measure, but 3.9% met criteria for autistic because such children may be at risk for other developmental disorder on both assessments, a prevalence rate more than difficulties. In a survey of over 1000 children, Horwitz et al. three times greater than would be expected from the general (2003) found that late-talkers tended to show poor social population (Baird et al., 2006). A further 26% met criteria interaction, which was in turn associated with an increased on one or other measure but not both. Similar results were risk of emotional and behavioral disorders. Furthermore, it obtained by Bishop and Norbury (2002), who noted that many would seem prudent to give the child support in the early stages children with language impairment displayed difficulties with of reading and writing, given a suggestion that there is a broader aspects of communication and social interaction, risk of weak literacy skills in children who were late-talkers although restricted interests and rigid behaviors were less (Rescorla, 2005). characteristic of this population. In cases where a child meets criteria in one or two domains Autism and Pragmatic Language Impairments of the autistic triad or exhibits subthreshold symptomatology Delayed language development and poor communication skills across domains, a diagnosis of “pervasive developmental dis- are hallmarks of autistic disorder, and the issue of differen- order not otherwise specified” or “atypical autism” is frequently tial diagnosis between autistic disorder and specific develop- applied. However, there is concern that these terms may mental language disorder frequently crops up in the clinical be overused, and do not provide helpful information about setting. Diagnosis of autistic disorder is covered in detail in symptom profile, nor do they facilitate decisions about educa- chapter 46, so in this chapter we focus on areas of diagnostic tional placement. Bishop (2000) suggested that the term “prag- difficulty. matic language impairment” (formerly “semantic-pragmatic Autistic disorder should be considered when the child’s disorder”) might be useful for describing children who do meet language difficulties are accompanied by more pervasive diffi- full diagnostic criteria for autistic disorder, but whose language culties affecting social interaction, non-verbal communication difficulties affect social interaction and the use of language and play, or if the child shows unusual repetitive or ritual- in context. The use of this term was not intended to imply a istic behaviors or restricted interests. The clinician needs to new and discrete disorder; rather, “pragmatic language impair- consider whether language development is merely delayed, or ment” is seen as a variable correlate of both SLI and milder whether there are deviant features that would not be regarded forms of autistic spectrum disorder (Norbury, Nash, Bishop, as normal at any age, such as repetitive use of stereotyped & Baird, 2004). catchphrases, unusual and exaggerated intonation, pronoun In reality, the diagnostic label chosen may reflect the reversal or a frequent failure to respond when the parent practitioner’s theoretical stance and the practical implications attempts to attract the child’s attention. a particular diagnosis brings with regard to accessing appro- Some higher functioning children with autistic disorder (i.e., priate educational and remedial provision. The important those children with non-verbal IQs within the normal range) point to recognize is that rather than attempting to draw a resemble our illustrative child Jack in having superficially discrete diagnostic line between SLI and autistic disorder, it complex language; they may appear verbose and achieve age- is more helpful to think in terms of multidimensional space, 789
  10. 10. 9781405145923_4_047.qxd 11/7/07 1:59 PM Page 790 CHAPTER 47 with children varying in terms of the severity of impairments Assessment of the child with SM may be particularly in language, social interaction and range of interests. challenging, as the assessment process itself might further increase anxiety and reluctance to speak. At first meeting, it Selective Mutism is most important to create a relaxed atmosphere in which the Occasionally, the clinician will encounter a child who is child feels little pressure to communicate with an unfamiliar extremely reticent in the clinic setting. In these instances, it is adult. In this session, the clinician may take a detailed case important to establish that the child does speak with others history from the parents, focusing on where, when and with in more familiar situations such as school and home. However, whom the child does speak and obtaining detailed examples if the child’s communication varies significantly in different of how the child communicates in different settings. During settings, the practitioner should consider the possibility of select- conversation with the parents, the clinician may unobtrusively ive mutism. observe the child playing and, if possible, interacting with Selective mutism (SM) is diagnosed in the child who parents or siblings. consistently does not speak in certain situations in which there Direct assessment of expressive language may not be is an expectation for speaking (i.e., school), but can and does possible at this point, although many children with SM will speak normally in some situations (e.g., at home; Steinhausen cooperate with receptive language testing if this just involves et al., 2006). The disorder was previously known as “elec- carrying out commands or pointing to pictures, and this tive” mutism, but the terminology has been revised to avoid can give valuable information about general language level implying that children are being obstinate or oppositional when (Manassis et al., 2003). Formal assessment may be supple- they remain silent (Cline & Baldwin, 2004; Cohan, Chavira, mented by asking parents to record the child’s language skills & Stein, 2006a). in a more comfortable arena, perhaps telling a story at home, DSM-IV-TR (American Psychiatric Association, 2000) and or keep a diary of what the child says and the contexts in ICD–10 (World Health Organization, 1996) criteria stipulate which language occurs. Johnson and Wintgens (2001) provide that in order to receive a diagnosis, the mutism must persist further examples of techniques for gaining the child’s con- for more than 1 month (not including the first month of fidence to enable assessment to proceed. school), and cannot be accounted for by a communication The most successful treatments are thought to combine beha- disorder or a lack of familiarity with the ambient language vioral and psychopharmacological interventions, but there of the social situation. Toppelberg, Tabors, Coggins, Lum, appears to be no systematic research on the efficacy of this and Burger (2005) further recommend that bilingual children approach (Cline & Baldwin, 2004). Cohan et al. (2006a) con- are not diagnosed with SM unless the mutism persists for longer ducted a critical review of psychosocial treatments published than 6 months and is apparent in both languages. over a 15-year period. The techniques used in these studies Prevalence estimates vary depending on the criteria used and included positive reinforcement for speaking to classmates, sys- the population studied, with higher rates of transient mutism tematic desensitization to anxiety-provoking situations, lan- associated with starting school. Cline and Baldwin (2004) guage training, family therapy and self-modeling techniques, estimate 6– 8 cases of selective mutism per 1000 through- in which the child with SM listens to recordings of him or out childhood, with a preponderance of girls (55–65% of herself speaking in situations in which he or she is usually mute. cases), consistent with the results of recent community studies, Although the majority of these studies report increases in which have found rates of approximately 75% (Cohan et al., speaking behavior, the findings are limited by very small par- 2006a). ticipant numbers and a lack of suitable control groups. The precise cause(s) of SM is unknown; although trauma A recent longitudinal study demonstrated considerable may precipitate mutism, it is not implicated in the majority improvement in symptoms of SM over time, but rates of of cases (Steinhausen & Juzi, 1996). SM is generally regarded psychiatric disorder, especially social phobia, remained high as a variant of anxiety disorder (Steinhausen et al., 2006; (Steinhausen et al., 2006). Prognosis is especially poor when !# Vecchio & Kearny, 2005), rather than being categorized with speech and language disorders. Rates of comorbid anxiety and a family history of SM is present. phobic disorders are high, both in affected children and their Assessment of Language and Communication first-degree relatives, and some success in treatment has been Approximately 50% of children referred for psychiatric reported using drugs that effectively reduce anxiety (for a review evaluation have clinically significant language impairments that see Cline & Baldwin, 2004). However, it would be wrong to are frequently unsuspected (Cohen, 2001). In many clinical con- imply that social anxiety is the only problem; other factors texts it is not possible to offer the time and expertise neces- are also often implicated, including bilingualism and speech sary for every referral to receive an in-depth assessment of and language impairment, suggesting that self-consciousness language. However, it can be informative to gain an overview about inadequate communication plays a part in maintaining of the child’s language development and current communicat- the disorder (Manassis et al., 2003). The consensus of opinion ive functioning by taking a detailed case history and asking is that SM is the culmination of multiple predisposing, pre- caregivers to complete a screening checklist. cipitating and perpetuating factors (Cohan, Price, & Stein, The Children’s Communication Checklist-2 (CCC-2; Bishop, 2006b; Johnson & Wintgens, 2001). 2003a) is a 70-item checklist for children aged 4 years and 790
  11. 11. 9781405145923_4_047.qxd 11/7/07 1:59 PM Page 791 SPEECH AND LANGUAGE DISORDERS over that asks parents to rate the frequency of communicative expressive subtypes of language disorder. The importance behaviors in everyday situations, thus providing a naturalistic of establishing level of receptive language cannot be under- assessment of functioning. One advantage of this assessment estimated: poor comprehension is an important predictor of is that it covers both structural aspects of language (phonology outcome in a language-impaired child (Stothard et al., 1998). and syntax) as well as pragmatic aspects of communication, However, if strictly interpreted, the DSM-IV system is unwork- which are more difficult to measure on face-to-face assessment. able. This is because it defines Expressive Language Disorder The CCC-2 reliably distinguishes children with communica- as having an expressive language score that is “substantially tion impairment from typically developing children (Norbury below” both non-verbal IQ and receptive language, whereas et al., 2004) and an earlier version of the checklist identified in Mixed Receptive-Expressive Language Disorder, both ex- children at genetic risk for language impairment as effectively pressive and receptive language are “substantially below” as standardized tests (Bishop, Laws, Adams, & Norbury, non-verbal IQ. This creates a problem of how to categorize 2006b). However, it should be noted that CCC-2 is not suit- a child with average non-verbal IQ and a mild receptive able for children who are not yet speaking in sentences. language impairment and a more severe expressive impairment More detailed evaluation of language and communicative (e.g., receptive language score is 0.8 SD below average and functioning will typically be undertaken by a speech-language expressive language score is 1.2 SD below average). If we therapist or specialist psychologist. A number of standardized interpret “substantially below” in terms of a 1-SD discrepancy, assessments tapping all domains of language are available in such a child would not meet criteria for either DSM subtype. English, but this is not necessarily so in other languages. The Furthermore, the distinction between the two subtypes seems application of English language assessments to children from artificial; both genetic and developmental data suggest that they non-English speaking backgrounds is not recommended, as test correspond to points on a continuum of severity (Bishop, North, scores may not accurately reflect the child’s competence in his & Donlan, 1995). or her native language. There is evidence that “knowledge-dependent” measures, such Prevalence, Causes and Correlates of Specific as vocabulary tests, exaggerate cultural and socioeconomic Language Impairment differences between children, whereas “processing” measures Research on SLI is complicated by the variety of diagnostic that vary difficulty by manipulating the amount of material criteria that have been employed. It is rather unusual to find that has to be processed (e.g., nonsense word repetition), research that focuses on “pure” SLI in which there is a provide a culturally unbiased estimate of language ability substantial discrepancy with non-verbal IQ. More commonly, (Campbell, Dollaghan, Needleman, & Janosky, 1997). Table an IQ cut-off is used to establish that children are within 47.1 provides a list of commonly used language assessments in the UK, including the domain of language targeted and the broadly normal limits. In addition, as noted in chapter 45, SLI is often accompanied by other neurodevelopmental dis- !$ age range appropriate for testing. orders: rates of co-occurrence of ADHD, developmental co- There is currently no clear consensus on what degree of ordination disorder and academic difficulties are all high. impairment on standardized assessment constitutes a significant Studies vary in how far they explicitly include or exclude difficulty. A score of –1 SD (equivalent to 16th centile) on a children with these comorbid conditions, with speech prob- single assessment may not interfere with the child’s educational lems or with autistic features. It is likely that estimates of or social development, whereas consistently low scores across prevalence, comorbidity and etiology will depend on the phe- a number of language domains or an extremely low score on notype that is studied. one measure (–2 SD or 3rd centile) may be more problematic. Tomblin, Records, and Zhang (1996) used a battery of lan- Prevalence guage tests covering different aspects of receptive and ex- The most frequently cited prevalence figure for SLI comes from pressive processing, and combined these into five composites: an epidemiological study by Tomblin et al. (1997), who estim- expressive language, comprehension, vocabulary, grammar ated that 7.4% (95% confidence interval [CI] 6.3–8.5%) and narrative. SLI was diagnosed if two or more of these com- of 5- to 6-year-old children in an Iowa sample met diag- posites fell more than –1.25 SD below age level (10th centile), nostic criteria as defined above. Intriguingly, of those who did non-verbal IQ was 87 or more, and no exclusionary con- meet criteria for SLI, only 29% had previously been identified ditions were present. In a population sample, this resulted as having language difficulties. If the criteria were made in 0.85 sensitivity (identifying true cases of impairment) and more stringent, to include only those with composite language 0.99 specificity (correctly identifying unimpaired cases). Note scores more than 2 SD below average, it was still the case that the definition of SLI used by Tomblin et al. was con- that only a minority of affected children (39%) had been siderably less stringent than that of ICD-10 (World Health identified clinically. This result suggests that the features that Organization, 1996), which requires that language test scores lead to a child being identified as having an SLI are different must be 2 SD or more below age level. Application of this from those that are picked up by standardized tests (Bishop criterion would give a lower prevalence rate. In DSM-IV-TR (American Psychiatric Association, 2000) a et al., 2005). In general, teachers and parents will notice a child whose speech is unclear or whose language structure !% distinction is drawn between expressive vs. mixed receptive- is so immature as to sound ungrammatical, but poor verbal 791
  12. 12. 9781405145923_4_047.qxd 11/7/07 1:59 PM Page 792 CHAPTER 47 memory, limited understanding, weak vocabulary and lack of referred to out-patient mental health clinics had clinically complex grammar are easier to miss. significant language impairments (for review see Cohen, 2001). As with many other neurodevelopmental disorders, more Such co-occurrences raise a host of questions about causa- males than females are affected with SLI, although the male tion. An obvious possibility is that inability to express ones preponderance was far less in the epidemiological study of needs and ideas leads to a sense of frustration and impotence, Tomblin et al. (1997), who reported 1.33:1 boys to girls, than and subsequent acting-out behavior. However, if this were the in samples recruited from clinical sources (e.g., Robinson, 1991, principal route to psychiatric disorder, we would expect the reported a ratio of 3.8:1). There is no evidence that different greatest evidence of psychopathology to be seen in children genetic influences are implicated in causing language impair- with expressive difficulties, whereas most studies find re- ment in males and females; a comparison of same-sex and ceptive language difficulties pose substantially greater risk. opposite-sex twin pairs found similar magnitude of genetic Failure to comprehend language can lead to inappropriate and environmental influences in both sexes (Viding et al., accusations in the classroom of laziness, willfulness or inat- 2004). tention, and it will also limit the opportunities to form close As Tomblin et al. (1997) pointed out, there is an intrinsic relationships that would normally exert a protective effect. difficulty in attempting to compare prevalence in different racial Redmond and Rice (1998) contrasted this latter type of groups, because even if the core language is the same across “social adaptation” account with a “social deviance” model races, there are likely to be cultural differences in language that regards both behavior and language problems as use that will lead to biased test results. Campbell et al. (1997) indicators of an underlying trait of disturbed psychosocial suggested such bias could be eliminated by avoiding language development. They argued that parent and teacher ratings tests that were affected by prior knowledge or experience, but of socioemotional status in children with SLI showed little we are not aware of any epidemiological studies that used such congruence or temporal stability, supporting the idea that beha- measures to compare different rates of SLI in different races vioral problems were consequences of specific communicative or cultures. experiences rather than reflecting intrinsic deficits in the child. However, rates of behavior disorder were relatively low Correlates of SLI in their sample, and the possibility remains that more severely Although SLI is “specific” in so far as the language disorder affected children have socioemotional deficits that go beyond is not accompanied by low non-verbal ability, there are what could be reasonably regarded as adaptations to poor com- frequently accompanying impairments in other aspects of munication (see also Bishop, 2000). functioning. Literacy problems are found in most but not all Another route from language impairment to psychiatric children with SLI; the question of what characterizes those disorder is through the experience of school failure. Both children who learn to read and write despite SLI is intriguing Beitchman et al. (1996) and Tomblin, Zhang, Buckwalter, and but as yet not fully understood; however, poor phonological Catts (2000) found that the risk of psychiatric disorder was !^ processing appears a key factor (Bishop & Snowling, 2004; Catts, Adlof, Hogan, & Ellis Weismer, 2005), Another fre- substantially raised in those children whose language impair- ment was accompanied by reading disability, and was much quent accompaniment to SLI is motor impairment, which lower in those who were experiencing academic success. In may not be evident in everyday interactions, but becomes so both these studies, this association was less evident when the on formal testing (Hill, 2001; Webster, Majnemer, Platt, & same children’s behavior problems were assessed before they Shevell, 2005). learned to read; this suggests that it is experience of school failure that exacerbates psychiatric risk. Comorbidity with Psychiatric Disorder One further mechanism whereby language could affect Early research by Cantwell and Baker (1991) demonstrated psychiatric status is through its role in inner speech and self- a high rate of psychiatric disorder, including but not limited regulation. Language is a tool for thought as well as a means to ADHD, in children referred for speech and language dis- of communication, and it affects how we structure our experi- orders. In one of the few epidemiological studies to address ences, plan for the future and reflect on the past. A child with this issue, the Ottowa Longitudinal Study, it was found that limited language understanding is anchored more firmly in the language impairment in 5-year-olds was one of the strongest here and now, and may find it hard to delay gratification, think predictors of psychiatric outcome at 12 years of age, even after through another person’s motivations or appreciate chains of measures of social background were taken into account (for causality. In the case of autistic disorder, verbal ability is review see Beitchman, Brownlie, & Wilson, 1996). In this study, strongly linked to the development of understanding of other ADHD and emotional disorders were the most common minds, thought to mediate social understanding and inter- psychiatric diagnoses. A series of studies by Cohen et al. also action (Happé, 1995) and those children with significantly demonstrated the converse. Of children referred for psychi- lower verbal ability in relation to non-verbal ability demon- atric assessment solely for socioemotional disturbances, 33% strate the most severe deficits in social interaction (Joseph, were found to have previously undiagnosed language impair- Tager-Flusberg, & Lord, 2002). ment. When combined with those whose language impairments We need more research relating specific aspects of language had already been identified, some 50% of school-aged children skill to cognitive processes and behavioral outcomes in SLI to 792

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