Chapter 16 Interactions between Speech Sound Disorder and Dyslexia

1. Chapter 16Interactions between Speech Sound Disorder and Dyslexia Beate Peter

2. Introduction • Written language is acquired several years after spoken language • This is true for all types of representing speech sound with symbols (logographic symbols, alphabetic script, syllabaries) • In English, the relationship between alphabetic symbols and speech sounds is extraordinarily complex • The purposes of this chapter: • Describe the core and associated characteristics of dyslexia • Show how dyslexia and speech sound disorder (SSD) are related • Consider possible subtypes and shared substrates in dyslexia and SSD

3. The Written Code of English • “pleaf,” “meng,” “shextine”: these are all pseudowords you can decode if you know the regular orthography of English • Unambiguous phoneme/grapheme relationship for “m, n, f” • Two symbols, one sound for “sh” (digraph) • One symbol, two sounds: “x” • Rules: • The magic e makes the vowel say its name (“makes,” “name”) • When two vowels go walking, the first one does the talking (“sea,” “road,” “rain”)

4. More complex grapheme/phoneme relationships • One phoneme can be represented by several graphemes • /i/ can be represented with “ea” (“sea”), “ee” (“see”), “ie” (“believe”), “ei” (“receive”), or “e” + consonant (C) + “e” (“cede”) • One grapheme can stand for several phonemes (although this occurs less frequently) • “th” before a vowel is used to represent both /θ/ (“thistle”) and /ð/ (“this”) • English has a deep (“opaque”) orthography • Examples for shallow (“transparent”) orthographies are Spanish and Italian

5. English contains many sight words that must be memorized because they do not follow standard rules • “have,” “done,” “gone” all defy the magic e rule • “bread” defies the rule about the two vowels going walking • “caught,” “sought,” “draught,” “laugh,” and “should” are full of silent letters and other irregularities • Reasons for these irregularities • English has many grandparents • Anglo-Saxon: “answer” • Vikings: “horse,” “wagon,” “sell” • French: “indict,” “jury,” “sovereign” • Latin and Greek: “-tion,” “bio-” • English orthography does not reflect historical changes in pronunciation patterns • “knee,” “knife,” “honor” used to be pronounced without silent letters • “Thus an intelligent child who is bidden to spell debt, and very properly spells it d-e-t, is caned for not spelling it with a b because Julius Caesar spelt the Latin word for it with a b.” (George Bernard Shaw, 1942)

6. Mastery of any alphabetic writing system requires • Phonemic awareness so that units of sound can be associated with units of spelling • Knowing that letters are arranged in directional sequences • Knowing that printed words represent sentences and concepts • Knowing how to hold a book • Mastery of English also requires • Learning the complex sound/letter relationships • Automatized recognition of sight words by shape • Understanding that each word consists of at least one syllable and that each syllable contains one vowel (both in sound structure and spelling)

7. Dyslexia • Dyslexia is specific disability that interferes with the acquisition of written language • at the word level, • characterized by deficits in accurate and/or fluent word recognition, decoding, and spelling. • These difficulties are not associated with variations in cognitive ability or quality of reading instruction, • and they are thought to have a neurobiological origin. (International Dyslexia Association) • What dyslexia is NOT: • A 10-year-old boy who had been kept from going to school and could not read in 4th grade. (Lack of access to instruction) • A girl in 5th grade who could read words without problems but could not answer questions about paragraphs she read. (Perhaps poor inferencing skills or memory problems) • A girl in 6th grade who also had difficulty following orally presented information. (General comprehension deficit) • In the past, poor readers only qualified for extra help if their reading scores were lower than their verbal or nonverbal IQ scores (discrepancy criterion). • Alternative: Response to Intervention (2004 Reauthorization of the Individuals with Disabilities Education Act (IDEA) )

8. Associated Behaviorally Observed Deficits • NOTE: Not all associated traits might be present in the same individual! • Auditory perception of nonspeech sounds that were presented rapidly • Phonological processing skills (dissect words into parts, deleting sounds, moving sounds) • Phonological short-term memory: nonword repetition tasks • Retrieving word forms from long-term memory, e.g., in rapid naming tasks • Slowed processing speed • Children with dyslexia had slower response times than typical controls during motor, visual, lexical, grammatical, and phonological measures as well as in rapid naming (Catts, Gillispie, Leonard, Kail, & Miller, 2002) • Everyone seems to have a built-in speed limit across various timed tasks and children with poor reading scores have slower speed limits than children with average reading scores (Peter & Raskind, 2011)

9. Associated Anatomical and Physiologic Deficits • Brain structures • Grey matter • Abnormal neuron migration to cortical layers • Planumtemporale in left and right hemisphere equal in size (typically, it is smaller in the right hemisphere) • White matter • Left hemisphere in temporoparietal tracts • Corpus callosum • Brain functions • Underactivation in the left fusiformgyrus (occipitotemporal system) where visual information is processed to facilitate word recognition • Underactivation in the left superior temporal gyrus (temporoparietal system (where phonological information is processed) • Underactivation or overactivation in the left inferior frontal gyrus

10. Brain activation in typical readers Temporoparietal system, including planumtemporale, angular gyrus (phonological processing) Inferior frontal gyrus, including Broca’s area (articulatory recoding) Occipitotemporal system, including fusiformgyrus (word recognition)

11. Brain activation in readers with dyslexia Inferior frontal gyrus, includes Broca’s area: over- or underactivated

12. Genetic Findings Strong evidence of a genetic etiology Causal gene(s) not yet identified Nine major candidate regions on chromosomes 1, 2, 3, 6, 15, 18, and X New regions continue to be identified

13. Demographics of Speech Sound Disorder and Dyslexia • Miles: first-grader with massive difficulties in speech and also in learning to read: coincidence or due to the same deficit? • SSD • 15.6% of three-year-old children (Campbell et al., 2003). Criterion: 75% intelligible speech • 3.8% in 6-year-old children (Shriberg et al., 1999). Criterion: - 1.14 SD in a 20-item articulation test • 1.1% in Australian 1st – 6th graders, using teacher report and SLP report (McKinnon et al., 2007) • Dyslexia • 5% to 9% of school-age children (reviewed in Francks et al., 2002; Pennington & Bishop, 2009; Peterson et al., 2007)

14. Simple view of reading (Gough & Tunmer, 1986 Subtypes by reading skill Intact word recognition but impaired decoding: “phonological dyslexia Intact decoding but impaired word recognition: “surface dyslexia” Both skills impaired: “deep dyslexia” Sight words can be trained; persistent difficulty with decoding is seen more frequently in children with dyslexia

15. SSD and Dyslexia Comorbidity SSD alone (not including childhood apraxia of speech, CAS): no elevated risk of developing dyslexia in school years (Lewis et al., 2004) CAS alone: substantial difficulties with reading and spelling (Lewis et al., 2004) SSD + phonological deficits: substantial difficulties with reading and spelling, regardless of whether language impairments were seen (Bird et al., 1995) SSD that persists into the school years: lower scores in reading, reading comprehension, spelling, and math, compared to children whose SSD had resolved prior to entering school (Nathan et al., 2004) SSD + language impairment: substantial difficulties with reading and spelling (Sices et al., 2007)

16. Substrates Common to Speech Production and Literacy Skills Phonological awareness and processing Sequential processing (possibly) It is possible that there is a shared genetic etiology

17. Connections It is possible that certain SSD subtypes are more susceptible to reading difficulties. Chapter 15 focuses on SSD subtypes. Chapter 22 describes professional settings where speech-language pathologists join service teams working with children who struggle with reading and spelling

18. Concluding Remarks SLPs frequently work with children with SSD and/or language impairment who also struggle with written language Good coordination among the team of service providers can enhance treatment efficacy, for instance when the underlying deficit is in phonological awareness and processing Additional research is needed to better understand the biological aspects of SSD and dyslexia comorbidity