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DYSLEXIA, DYSGRAPHIA, AND ADHD Carol Wilkinson, Jessica Witkowski, and Jenna Klotz
Development and Behavioral Pediatrics
September 11, 2012
Dyslexia
¨ DefiniNon ¤ Characterized by difficulNes with accurate word recogniNon, poor spelling and decoding abiliNes n Must not be due to inadequate instrucNon n Must occur in context of normal cogniNve funcNoning
¨ A neurobiological condiNon
Background
¨ Most common learning disability ¤ Boys > girls
¨ Risk factors ¤ Family history ¤ History of SLI ¤ Environmental: low exposure to books and instrucNon in pre-‐reading skills, poverty, low parental educaNon.
• Recognizes leZers and words • Form assoc. with leZers that co-‐occur • Allows for recogniNon of words that don’t follow typical leZer-‐sound correspondence (i.e. yacht)
• Forms associaNons of words/syllables with sounds (phonemes) • Back up the larger system (used to “sound out” an unknown word)
• Facilitates understanding of meaning of words as they are read
• Understanding of text being read • Uses syntax, semanNc, and pragmaNc knowledge
Phonological deficit hypothesis
¨ Lack of phonemic awareness blocks access to higher order process involved in comprehension. ¤ Several studies have shown children with dyslexia are impaired in phonological processing tasks n Example: Children with dyslexia and normal readers were compared with reading one and two-‐syllable nonwords
n Dyslexics made more errors in reading nonwords aloud, especially with phonological complexity (p < 0.05)
Neurobiology
¨ DisrupNon of led hemisphere posterior brain systems ¨ Study of 24 dyslexic children and 15 normal reading children ¤ Asked to press a buZon when 2 visually presented leZers rhymed (ie D and T) and then when 2 leZers were the same (D and D) n By comparing, can determine which brain acNvity was due to phonological demands (rhyme task) vs. orthographic (same leZers)
¤ Asked to press a buZon when 2 leZers matched and then when 2 lines had the same orientaNon (ie I and I) n To determine brain acNvity due to orthographic processing
Behavioral Results
¨ Dyslexic children were less accurate for rhyme leZers (p = 0.05)
¨ No difference between groups for match leZers or match lines (p > 0.1)
¨ Performance on rhyme task correlated with reading for all subjects (p = 0.005)
Rhyme vs. LeZer Matching ¨ Both groups showed
acNvaNon of led frontal lobe with leZer match
¨ Normal reading children show led temporo-‐parietal regions with rhyming
¨ Dyslexic children showed no acNvaNon of led temporo-‐parietal cortex with rhyming
¨ Led temporo-‐parietal region not acNvated in leZer match task ¤ Deficit is phonological
LeZer Match vs. Line Match
¨ Several regions showed greater acNvity in normal reading children
¨ Dyslexic children did not show acNvity in the occipital-‐parietal area (p=0.02)
¨ Difference in orthographic processing for dyslexia children
References
¨ Grizzle, Kenneth L. “Language and Learning: A Discussion of Typical and Disordered Development.” Current Problems in Pediatric and Adolescent Health Care. Vol 39 (7) Aug. 2009, 168-‐189.
¨ Hamilton, SuZon. “Normal Reading Development and ENology of Reading Difficulty in Children.” UpToDate.
¨ Peterson, Robin L. “Neuropsychology and GeneNcs of Speech, Language, and Literacy Disorders.” Pediatric Clinics of North America. Vol 54 (3). June 2007. 543-‐561.
¨ Snowling, Margaret J. “Phonemic Deficits in Developmental Dyslexia.” Psychological Research. Vol 43. 1981. 219-‐234.
¨ Temple, Elise. “Disrupted Neural Responses to Phonological and Orthographc Processing in Dyslexic Children: an fMRI study.” Neuroreport. Vol 12 (2), Feb 2001. 299-‐307
Developmental Dysgraphia
¨ WriNng skills below those expected for a person’s age or ability, despite appropriate educaNon
¨ Illegible handwriNng, leZer shape distorNons, dysfluent wriNng, spelling errors or other difficulty in wriZen expression that cannot be aZributed to disabiliNes in reading, oral expression, intellectual disability, impaired vision or hearing, or other neurological disorders
Developmental Dysgraphia
¨ 10-‐30% with “difficulty” v. 2-‐4% with “disability” ¤ Must significantly impair academic achievement and/or ADLs
¨ Rarely resolves without intervenNon
Neural Basis of WriZen Expression
Purcell et al. Written production ALE meta-analysis
emission tomography (PET) and functional magnetic resonanceimaging (fMRI) studies of word spelling in alphabetic languageinvolving adult participants.
Producing written words involves a number of interactingcognitive processes that have been described in various modelsof written language production (Roeltgen and Heilman, 1985;Rapp and Caramazza, 1997; Rapcsak and Beeson, 2002; Hillis andRapp, 2004). Although these cognitive processes are highly inte-grated, an important distinction is often made between centraland peripheral components (see Figure 1). The different patternsof impairment that have been observed in cases of acquired dys-graphia subsequent to brain lesions have constituted the majorsource of empirical support for the distinctions between centraland peripheral processing components as well as for the more fine-grained distinctions described below and depicted in Figure 1. Inaddition, convergent evidence for many of these distinctions hasbeen confirmed by behavioral studies of spelling and writing inneurologically healthy participants. While it is outside the scopeof this paper to review these literatures, we refer the interestedreader to various reviews (Ellis, 1979; Burt and Fury, 2000; Burtand Tate, 2002; Weingarten, 2005).
Spelling typically begins by hearing words (e.g., taking notesin a lecture, a message over the phone, etc.) or with inter-nally generated word meanings (e.g., writing a letter, a gro-cery list, etc.). These auditory comprehension and semanticprocesses and mechanisms are not specific to spelling, yetserve as the basis for the subsequent retrieval or assembly ofspellings. Spelling-specific, central processes are usually identifiedas: orthographic long-term memory (O-LTM; the orthographic
lexicon), phoneme–grapheme (PG) conversion, and orthographicworking memory (the graphemic buffer). O-LTM is the store ofthe word spellings that an individual is familiar with. As indicatedin Figure 1, information in O-LTM may be retrieved on the basis ofa word’s meaning or, according to some researchers, directly froma representation of the word’s sound (Patterson, 1986). In addi-tion to retrieval from O-LTM, word spellings may be assembledfrom a phonological stimulus via the PG conversion processes thatapply learned information regarding the relationships betweensounds and letters (or other sub-lexical units) to generate plausi-ble spellings for sound strings. For example, the sound stimulus“wuns” could result in the retrieval of the information O-N-C-Efrom O-LTM and/or in the assembly of a plausible spelling suchas W-U-N-S-E from the PG conversion system. The letter rep-resentations assembled or retrieved are assumed to be abstract,lacking format-specific information (such as shape, size, motorplan, etc.). The abstract letter strings are then processed by O-WM, a limited capacity system responsible for maintaining letteridentity and order information active so that they can be selectedfor further processing by peripheral components (Rapp and Kong,2002; Kan et al., 2006). These central processes interact with oneanother, with evidence specifically supporting bi-directional inter-actions between O-WM and O-LTM (McCloskey et al., 2006)and between O-LTM and PG conversion processes (Rapp et al.,2002).
In terms of peripheral processes, it is generally assumed thatthere are multiple stages involved in going from the abstract lettersrepresentations in O-WM to the correct ordering and executionof the effector-specific muscle movements required for expressing
FIGURE 1 | A schematic depiction of the cognitive architecture of the written word production system.
Frontiers in Psychology | Language Sciences October 2011 | Volume 2 | Article 239 | 2
Purcell et al., 2011
“Central” Processing
Long term orthographic memory (storage)
Long term orthographic memory (retrieval)
Phoneme to grapheme conversion
Orthographic working memory
“Peripheral” Processing
Conversion of graphemic representaNon to motor commands
Sequence of motor commands
Types of Dysgraphia
Linguis'c Dysgraphias Features Phonological Can not convert phoneme à grapheme,
but can copy leZers. Phonologically incorrect misspelled words.
Lexical Can not learn or recall lexically (recognize full words). Misspells words, but phonologically correct.
Dyslexic Can not convert grapheme à grapheme. Misspellings with reversals, omissions, inversions, non-‐words.
Gerstmann Fluent incomprehensible order of leZers and words. Misspellings with jumbled sequences.
Types of Dysgraphia
Non-‐linguis'c Dysgraphias
Features
Motor Apraxic Poor penmanship. UnNdy wriNng with mild reversals.
IdeaNonal Apraxic Can copy wriNng examples, but can not write spontaneously.
ConstrucNonal Apraxic VisuospaNal difficulty. Reversals and inversions. Can not copy wriNng examples.
Diagnosing Dysgraphia
¨ Many cases may go unrecognized as these children are frequently viewed as lazy or non-‐compliant
¨ Standardized spelling tests ¤ Lexical errors: omission of silent leZers (whether à wether)
¤ SemanNc errors: homonyms (knight à night) ¤ Visuo-‐spaNal errors: deflecNons from line ¤ Graphemic/motor errors: fluency of wriNng
¨ Should also include numbers, copying reading samples appropriate for developmental age
IntervenNons for Dysgraphia
¨ Intensive remediaNon in handwriNng directed at specific deficit or learning disability
¨ CombinaNon therapy: i.e. focusing on both handwriNng and story-‐wriNng
¨ Bypass strategies ¤ Keyboarding ¤ Photocopied worksheets ¤ Oral test taking
Dysgraphia Summary
¨ Difficulty/disability in wriZen expression which impairs academics and ADLs
¨ Affects up to 30% of school-‐aged children ¨ Due to deficits in linguisNc learning, working memory, and motor planning
¨ IntervenNons should either target or bypass those deficits
References ¨ Adi-‐Japha E, Landau YE, Frenkel L, Teicher M, Gross-‐Tsur V, Shalev RS. ADHD and
Dysgraphia: Underlying Mechanisms. Cortex, 2007. 43:700-‐709. ¨ Feder KP and Majnemer A. HandwriNng development, competency, and
intervenNon. Developmental Medicine & Child Neurology. 2007. 49:312-‐317. ¨ Gubbay SS and de Klerk NH. A study and review of developmental dysgraphia in
relaNon to acquired dysgraphia. Brain & Development. 1995. 17:1-‐8. ¨ Molfese V, Molfese D, Molnar A, Beswick J. Developmental Dyslexia and
Dysgraphia. ¨ Purcell JJ, Turkeltaub PE, Eden GF, Rapp B. Examining the central and peripheral
processes of wriZen word producNon through meta-‐analysis. FronNers in Psychology. 2011.
¨ Zoccolou P and Friedmann N. From dyslexia to dyslexias, from dysgraphia to dysgraphias, from a cause to causes: A look at current research on developmental dyslexia and dysgraphia. Cortex. 2010. 46:1211-‐1215.
ADHD ComorbidiNes
¨ OpposiNonal defiant disorder ¨ Conduct disorder ¨ Anxiety ¨ Depression ¨ Dyslexia ¨ WriZen Language Disorder
ADHD and Dyslexia
ADHD and Dyslexia
Germano, Gagliano and Curatolo 2010
18-‐45% of children with ADHD have dyslexia 18-‐42% of children with dyslexia have ADHD
3 Hypotheses
¨ Phenocopy hypothesis ¤ “I can’t read easily, so I’m distracted…can I go to the bathroom?”
¨ Shared Ae=logy hypothesis
¤ ”Some of the genes that make it hard for me to focus also make it hard for me to understand phonemes.”
¨ Cogni=ve subtype hypothesis ¤ “I’m an individual and my ADHD/dyslexia is not the same as Jonny’s ADHD or Sally’s dyslexia.”
Research for geneNc influence
Both Dyslexia and ADHD are heritable. Targeted linkage studies have found 9 chromosome regions for dyslexia suscepNbility
Treatment of ADHD and Dyslexia
¨ Methylphenidate improves reading performance in children with ADHD and comorbid dyslexia
n Bental B and Tirosh E. J. Clin Psychopharm. 2008 n Keulers et al. Eur J Paediatr Neurol 2007
¨ fMRI of ADHD and RD teens both show decreased acNvaNon of led striatum and improvement with MPH.
n Shafritz et al. Am J Psychiatry 2004
ADHD and WriZen Language Disorders (WLD)
¨ DSM-‐IV: disorder of wriZen expression. ¤ GrammaNcal/punctuaNon ¤ Poor paragraph organizaNon ¤ Spelling Errors ¤ Poor handwriNng
Incidence of ADHD and WLD
¨ Children born between 1976-‐1982 in Rochester Minnesota
¨ Data from Rochester Epidemiology Project, school district records and 1 private tutoring agency
¨ 5718 children ¤ 2956 boys, 2762 girls ¤ 1509 children with complete assessment data
16.5%
9.4%
CummulaNve Incidence
16.5%
9.4%
64.5%
57.0%
No ADHD vs ADHD
CumulaNve Incidence
DistribuNon of WLD with RD
DistribuNon of WLD w/o RD
What type of dysgraphia?
• 40 right handed 6th grade boys • ages 11-‐13 • Normal IWQ, normal reading • ADHD combined type vs non-‐ADHD
What type of dysgraphia?
• Morphological spelling errors: house vs horse • Graphemic errors (motor programming) • Motor kinemaNc abnormaliNes: increased pressure, poor Nme uNlizaNon, inconsistent shapes/heights
NON_LINGUISTIC DYSGRAPHIA
Summary
¨ Clear increased incidence of Dyslexia and Dysgraphia in children with ADHD.
¨ Ongoing research into possible genes that affect both ADHD and Dyslexia
¨ Dysgraphia likely non-‐linguisNc, associated with problems in motor programming and kinemaNc motor producNon
References ¨ Germano E, Gagliano A, Curatolo P. Comorbidity of ADHD and Dyslexia. Developmental
Neuropsychology, 2010, 35(5): 475-‐493.
¨ Yoshimasu K, Barbaresi WJ, Colligan RC, Killian JM, Voight RG, Weaver AL, Katusi SK. WriZen-‐Language Disorder among children with and without ADHD in populaNon-‐based birth cohort. Pediatrics, 2011. 128: e605.
¨ Adi-‐Japha E, Landau YE, Frenkel L, Teicher M, Gross-‐Tsur V, Shalev RS. ADHD and Dysgraphia: Underlying Mechanisms. Cortex, 2007. 43:700-‐709.
¨ Eden GF and Chandan VJ. ADHD and Developmental Dyslexia. Annals Ny.Y Acad. Sci. 2008. 1145:316-‐327
¨ Keulers EH, et al. Methylphenidate improves reading performance in children with aZenNon deficit hyperacNvity disorder and comorbid dyslexia: an unblinded clinical trial. Eur. J Paediatr Neurol. 2007. 11:21-‐8.
¨ Bental B and Tirosh E. The effects of methylphenidate on word decoding accuracy in boys with aZenNon-‐deficit/hyperacNvity disorder. J Clin Psychopharmacol. 2008. 28: 89-‐92.
¨ Shafritz et al. The effects of methyphenodate on neural systems of aZenNon in aZenNon deficit hyperacNvity disorder. 2004. 161:1990-‐1997.
