Phonological awareness mediates the relationship between DCDC2 and reading performance with home environment

Proficient reading requires critical phonological processing skill that interacts with both genetic and environmental factors. However, the precise nature of the relationships between phonological processing and genetic and environmental factors are poorly understood. We analyzed data from the Genes, Reading and Dyslexia (GRaD) Study on 1419 children ages 8-15 years from African-American and Hispanic-American family backgrounds living in North America. The analyses showed that phonological awareness mediated the relationship between DCDC2-READ1 and reading outcomes when parental education and socioeconomic status was low. The association between READ1 and reading performance is complex, whereby mediation by phonological awareness was significantly moderated by both parental education and socioeconomic status. These results show the importance of home environment and phonological skills when determining associations between READ1 and reading outcomes. This will be an important consideration in the development of genetic screening for risk of reading disability.

Empowering Schools to Implement Effective Research-Based Reading Remediation Delivers Long-Lasting Improvements to Children's Reading Trajectories

There is a wide gap between what research evidence identifies as effective reading intervention and what is currently offered in schools. This effectiveness study reports the results of a long-term research/school system partnership that is implementing reading intervention for children with reading difficulties in community schools. In Study 1, growth-curve analyses revealed significant long-term shifts in the reading trajectories of children (n = 731) from Kindergarten to Grade 5 as a function of receiving the Empower™ Reading: Decoding and Spelling intervention. Long-term outcomes were higher in children who received intervention in Grade 2 than in Grade 3, supporting the benefit of earlier intervention. In Study 2, we compare reading outcomes before and after children participated in school system-led intervention (Empower™ Reading, n = 341) to results from previously reported researcher-led intervention and business-as-usual controls. Children in both school system-led and researcher-led interventions showed greater improvement than controls on standardized measures of decoding and reading comprehension. Among school system participants, greater gains were seen for those with stronger reading skills at pre-test. Findings demonstrate successful school system implementation of research-originated and validated reading intervention. Researcher/school system partnerships may be integral in closing the research-practice gap.

Language and reading impairments are associated with increased prevalence of non-right-handedness

Handedness has been studied for association with language-related disorders because of its link with language hemispheric dominance. No clear pattern has emerged, possibly because of small samples, publication bias, and heterogeneous criteria across studies. Non-right-handedness (NRH) frequency was assessed in N = 2503 cases with reading and/or language impairment and N = 4316 sex-matched controls identified from 10 distinct cohorts (age range 6-19 years old; European ethnicity) using a priori set criteria. A meta-analysis (Ncases  = 1994) showed elevated NRH % in individuals with language/reading impairment compared with controls (OR = 1.21, CI = 1.06-1.39, p = .01). The association between reading/language impairments and NRH could result from shared pathways underlying brain lateralization, handedness, and cognitive functions.

White matter correlates of reading subskills in children with and without reading disability

Individual differences in reading ability are associated with characteristics of white matter microstructure in the brain. However, previous studies have largely measured reading as a single construct, resulting in difficulty characterizing the role of structural connectivity in discrete subskills of reading. The present study used diffusion tensor imaging to examine how white matter microstructure, measured by fractional anisotropy (FA), relates to individual differences in reading subskills in children aged 8 to 14 (n = 65). Findings showed positive correlations between FA of the left arcuate fasciculus and measures of single word reading and rapid naming abilities. Negative correlations were observed between FA of the right inferior longitudinal fasciculus and bilateral uncinate fasciculi, and reading subskills, particularly reading comprehension. The results suggest that although reading subskills rely to some extent on shared tracts, there are also distinct characteristics of white matter microstructure supporting different components of reading ability in children.

Identification of brain cell types underlying genetic association with word reading and correlated traits

Neuroimaging studies implicate multiple cortical regions in reading ability/disability. However, the neural cell types integral to the reading process are unknown. To contribute to this gap in knowledge, we integrated genetic results from genome-wide association studies for word reading (n = 5054) with gene expression datasets from adult/fetal human brain. Linkage disequilibrium score regression (LDSC) suggested that variants associated with word reading were enriched in genes expressed in adult excitatory neurons, specifically layer 5 and 6 FEZF2 expressing neurons and intratelencephalic (IT) neurons, which express the marker genes LINC00507, THEMIS, or RORB. Inhibitory neurons (VIP, SST, and PVALB) were also found. This finding was interesting as neurometabolite studies previously implicated excitatory-inhibitory imbalances in the etiology of reading disabilities (RD). We also tested traits that shared genetic etiology with word reading (previously determined by polygenic risk scores): attention-deficit/hyperactivity disorder (ADHD), educational attainment, and cognitive ability. For ADHD, we identified enrichment in L4 IT adult excitatory neurons. For educational attainment and cognitive ability, we confirmed previous studies identifying multiple subclasses of adult cortical excitatory and inhibitory neurons, as well as astrocytes and oligodendrocytes. For educational attainment and cognitive ability, we also identified enrichment in multiple fetal cortical excitatory and inhibitory neurons, intermediate progenitor cells, and radial glial cells. In summary, this study supports a role of excitatory and inhibitory neurons in reading and excitatory neurons in ADHD and contributes new information on fetal cell types enriched in educational attainment and cognitive ability, thereby improving our understanding of the neurobiological basis of reading/correlated traits.

Hypothesis-driven genome-wide association studies provide novel insights into genetics of reading disabilities

Reading Disability (RD) is often characterized by difficulties in the phonology of the language. While the molecular mechanisms underlying it are largely undetermined, loci are being revealed by genome-wide association studies (GWAS). In a previous GWAS for word reading (Price, 2020), we observed that top single-nucleotide polymorphisms (SNPs) were located near to or in genes involved in neuronal migration/axon guidance (NM/AG) or loci implicated in autism spectrum disorder (ASD). A prominent theory of RD etiology posits that it involves disturbed neuronal migration, while potential links between RD-ASD have not been extensively investigated. To improve power to identify associated loci, we up-weighted variants involved in NM/AG or ASD, separately, and performed a new Hypothesis-Driven (HD)-GWAS. The approach was applied to a Toronto RD sample and a meta-analysis of the GenLang Consortium. For the Toronto sample (n = 624), no SNPs reached significance; however, by gene-set analysis, the joint contribution of ASD-related genes passed the threshold (p~1.45 × 10-2, threshold = 2.5 × 10-2). For the GenLang Cohort (n = 26,558), SNPs in DOCK7 and CDH4 showed significant association for the NM/AG hypothesis (sFDR q = 1.02 × 10-2). To make the GenLang dataset more similar to Toronto, we repeated the analysis restricting to samples selected for reading/language deficits (n = 4152). In this GenLang selected subset, we found significant association for a locus intergenic between BTG3-C21orf91 for both hypotheses (sFDR q < 9.00 × 10-4). This study contributes candidate loci to the genetics of word reading. Data also suggest that, although different variants may be involved, alleles implicated in ASD risk may be found in the same genes as those implicated in word reading. This finding is limited to the Toronto sample suggesting that ascertainment influences genetic associations.

Genome-wide analyses of individual differences in quantitatively assessed reading- and language-related skills in up to 34,000 people

The use of spoken and written language is a fundamental human capacity. Individual differences in reading- and language-related skills are influenced by genetic variation, with twin-based heritability estimates of 30 to 80% depending on the trait. The genetic architecture is complex, heterogeneous, and multifactorial, but investigations of contributions of single-nucleotide polymorphisms (SNPs) were thus far underpowered. We present a multicohort genome-wide association study (GWAS) of five traits assessed individually using psychometric measures (word reading, nonword reading, spelling, phoneme awareness, and nonword repetition) in samples of 13,633 to 33,959 participants aged 5 to 26 y. We identified genome-wide significant association with word reading (rs11208009, P = 1.098 × 10-8) at a locus that has not been associated with intelligence or educational attainment. All five reading-/language-related traits showed robust SNP heritability, accounting for 13 to 26% of trait variability. Genomic structural equation modeling revealed a shared genetic factor explaining most of the variation in word/nonword reading, spelling, and phoneme awareness, which only partially overlapped with genetic variation contributing to nonword repetition, intelligence, and educational attainment. A multivariate GWAS of word/nonword reading, spelling, and phoneme awareness maximized power for follow-up investigation. Genetic correlation analysis with neuroimaging traits identified an association with the surface area of the banks of the left superior temporal sulcus, a brain region linked to the processing of spoken and written language. Heritability was enriched for genomic elements regulating gene expression in the fetal brain and in chromosomal regions that are depleted of Neanderthal variants. Together, these results provide avenues for deciphering the biological underpinnings of uniquely human traits.

Language Difficulties in School-Age Children With Developmental Dyslexia

Developmental dyslexia (DD) is a common reading disability, affecting 5% to 11% of children in North America. Children classified as having DD often have a history of early language delay (ELD) or language impairments. Nevertheless, studies have reported conflicting results as to the association between DD-ELD and the extent of current language difficulties in children with DD. To examine these relationships, we queried the parents of school-age children with reading difficulties on their child's early and current language ability. Siblings were also examined. Children were directly assessed using quantitative tests of language and reading skills. To compare this study with the literature, we divided the sample (N = 674) into three groups: DD, intermediate readers (IR), and skilled readers (SR). We found a significant association between DD and ELD, with parents of children in the DD/IR groups reporting their children put words together later than the SR group. We also found a significant association between DD and language difficulties, with children with low reading skills having low expressive/receptive language abilities. Finally, we identified early language predicted current language, which predicted reading skills. These data contribute to research indicating that children with DD experience language difficulties, suggesting early recognition may help identify reading problems.

How you read affects what you gain: Individual differences in the functional organization of the reading system predict intervention gains in children with reading disabilities

There is now considerable evidence regarding the types of interventions that are effective at remediating reading disabilities on average. It is generally unclear, however, what predicts the magnitude of individual-level change following a given intervention. We examine new predictors of intervention gains that are theoretically grounded in computational models of reading and focus on individual differences in the functional organization of the reading system. Specifically, we estimate the extent to which children with reading disabilities (n=118 3^rd-4^th graders) rely on two sources of information during an oral word reading task - print-speech correspondences and semantic imageability - before and after a phonologically-weighted intervention. We show that children who relied more on print-speech regularities and less on imageability pre-intervention had better intervention gains. In parallel, children who over the course of the intervention exhibited greater increases in their reliance on print-speech correspondences and greater decreases in their reliance on imageability had better intervention outcomes. Importantly, these two factors were differentially related to specific reading task outcomes, with greater reliance on print-speech correspondences associated with pseudoword naming, while (lesser) reliance on imageability related to word reading and comprehension. We discuss the implications of these findings for theoretical models of reading acquisition and educational practice.

Genome-wide association study of word reading: Overlap with risk genes for neurodevelopmental disorders

Reading disabilities (RD) are the most common neurocognitive disorder, affecting 5% to 17% of children in North America. These children often have comorbid neurodevelopmental/psychiatric disorders, such as attention deficit/hyperactivity disorder (ADHD). The genetics of RD and their overlap with other disorders is incompletely understood. To contribute to this, we performed a genome-wide association study (GWAS) for word reading. Then, using summary statistics from neurodevelopmental/psychiatric disorders, we computed polygenic risk scores (PRS) and used them to predict reading ability in our samples. This enabled us to test the shared aetiology between RD and other disorders. The GWAS consisted of 5.3 million single nucleotide polymorphisms (SNPs) and two samples; a family-based sample recruited for reading difficulties in Toronto (n = 624) and a population-based sample recruited in Philadelphia [Philadelphia Neurodevelopmental Cohort (PNC)] (n = 4430). The Toronto sample SNP-based analysis identified suggestive SNPs (P ~ 5 × 10^-7 ) in the ARHGAP23 gene, which is implicated in neuronal migration/axon pathfinding. The PNC gene-based analysis identified significant associations (P < 2.72 × 10^-6 ) for LINC00935 and CCNT1, located in the region of the KANSL2/CCNT1/LINC00935/SNORA2B/SNORA34/MIR4701/ADCY6 genes on chromosome 12q, with near significant SNP-based analysis. PRS identified significant overlap between word reading and intelligence (R²  = 0.18, P = 7.25  × 10^-181 ), word reading and educational attainment (R²  = 0.07, P = 4.91 × 10^-48 ) and word reading and ADHD (R²  = 0.02, P = 8.70 × 10^-6 ; threshold for significance = 7.14 × 10^-3 ). Overlap was also found between RD and autism spectrum disorder (ASD) as top-ranked genes were previously implicated in autism by rare and copy number variant analyses. These findings support shared risk between word reading, cognitive measures, educational outcomes and neurodevelopmental disorders, including ASD.

Effect of READ1 on latent profiles of reading disorder and comorbid attention and language impairment subtypes

Recent studies of co-occurring reading disorder (RD) and attention deficit/hyperactivity disorder (ADHD), and co-occurring RD and language impairment (LI), support a core disability plus co-occurrence model focused on language and attention. Genetic factors have been associated with poor reading performance. However, little is known about whether different genetic variants independently contribute to RD co-occurrence subtypes. We aimed to identify subgroups of struggling readers using a latent profile analysis (LPA) in a sample of 1,432 Hispanic American and African American youth. RD classes were then tested for association with variants of READ1, a regulatory element within the candidate RD risk gene, DCDC2. Six groups were identified in the LPA using RD designation as a known-class variable. The three RD classes identified groups of subjects with neurocognitive profiles representing RD+ADHD, specific phonological deficit RD, and RD+LI. Genetic associations across RD subtypes were investigated against functional groupings of READ1. The RU1-1 group of READ1 alleles was associated with RD cases that were marked by deficits in both processing speed and attention (RD+ADHD). The DCDC2 microdeletion that encompasses READ1 was associated with RD cases showing a phonological deficit RD profile. These findings provide evidence for differential genetic contribution to RD subtypes, and that previously implicated genetic variants for RD may share an underlying genetic architecture across population groups for reading disorder.

Multivariate genome-wide association study of rapid automatised naming and rapid alternating stimulus in Hispanic American and African-American youth

BACKGROUND

Rapid automatised naming (RAN) and rapid alternating stimulus (RAS) are reliable predictors of reading disability. The underlying biology of reading disability is poorly understood. However, the high correlation among RAN, RAS and reading could be attributable to shared genetic factors that contribute to common biological mechanisms.

OBJECTIVE

To identify shared genetic factors that contribute to RAN and RAS performance using a multivariate approach.

METHODS

We conducted a multivariate genome-wide association analysis of RAN Objects, RAN Letters and RAS Letters/Numbers in a sample of 1331 Hispanic American and African-American youth. Follow-up neuroimaging genetic analysis of cortical regions associated with reading ability in an independent sample and epigenetic examination of extant data predicting tissue-specific functionality in the brain were also conducted.

RESULTS

Genome-wide significant effects were observed at rs1555839 (p=4.03×10-8) and replicated in an independent sample of 318 children of European ancestry. Epigenetic analysis and chromatin state models of the implicated 70 kb region of 10q23.31 support active transcription of the gene RNLS in the brain, which encodes a catecholamine metabolising protein. Chromatin contact maps of adult hippocampal tissue indicate a potential enhancer-promoter interaction regulating RNLS expression. Neuroimaging genetic analysis in an independent, multiethnic sample (n=690) showed that rs1555839 is associated with structural variation in the right inferior parietal lobule.

CONCLUSION

This study provides support for a novel trait locus at chromosome 10q23.31 and proposes a potential gene-brain-behaviour relationship for targeted future functional analysis to understand underlying biological mechanisms for reading disability.

A molecular-genetic and imaging-genetic approach to specific comprehension difficulties in children

Children with poor reading comprehension despite typical word reading skills were examined using neuropsychological, genetic, and neuroimaging data collected from the Genes, Reading and Dyslexia Study of 1432 Hispanic American and African American children. This unexpected poor comprehension was associated with profound deficits in vocabulary, when compared to children with comprehension skills consistent with their word reading. Those with specific comprehension difficulties were also more likely to have RU2Short alleles of READ1 regulatory variants of DCDC2, strongly associated with reading and language difficulties. Subjects with RU2Short alleles showed stronger resting state functional connectivity between the right insula/inferior frontal gyrus and the right supramarginal gyrus, even after controlling for potentially confounding variables including genetic ancestry and socioeconomic status. This multi-disciplinary approach advances the current understanding of specific reading comprehension difficulties, and suggests the need for interventions that are more appropriately tailored to the specific comprehension deficits of this group of children.

Achievement attributions are associated with specific rather than general learning delays

The causal attributions that children make for success and failure have been associated with later reading motivation and ability perceptions, which have the potential to impact future task engagement. Few studies have investigated whether such attributions are domain specific, that is linked with the specific skill in question, or a general motivational set. Even fewer studies have examined these relationships among diverse racial and ethnic subgroups. The present study examined differences in success and failure attributions among children with and without reading delay (RD) and general language impairments (LI), in a predominately Hispanic and African American sample. Participants were 1311 children, 8 to 15 years old. Significant differences in ability attributions were observed between participants with and without RD and LI, with no additive effect for cases with co-occurring reading and language impairments. When reading and vocabulary were evaluated continuously, significant and substantial positive relationships were observed between skill and ability attributions in situations of success, and negative associations observed in situations of failure. Weaker relationships were observed for vocabulary, though vocabulary did function as a moderator in the relationship between reading skill and ability attributions, with stronger associations at higher vocabulary levels. Overall, the findings suggest that ability attributions for reading success and failure are linked with reading skill and/or deficits, and not with general language impairments.

Reading-Related Causal Attributions for Success and Failure: Dynamic Links With Reading Skill

The present study investigated the relation among reading skills and attributions, naming speed, and phonological awareness across a wide range of reading skill. Participants were 1,105 school-age children and youths from two understudied populations: African Americans and Hispanic Americans. Individual assessments of children ranging in age from 8 to 15 years were conducted for reading outcomes, cognitive and linguistic predictors of reading, and attributions for success and failure in reading situations. Quantile regressions were formulated to estimate these relations across the full skill span of each outcome. Reading-related attributions predicted contextual word recognition, sight word and decoding fluency, and comprehension skills. Attributions to ability in success situations were positively related to each outcome across the full span. On three reading outcomes, this relation strengthened at higher skill levels. Attributions to effort in success situations were consistently and negatively related to all reading outcomes. The results provide evidence that the strength of the relation between reading and attributions varies according to reading skill levels, with the strongest evidence for ability-based attributions in situations of reading success.

Literacy promotion by health care professionals: A comprehensive biomedical and psychosocial approach

Literacy is the ability to read, write and understand print. Proficiency in literacy is fundamental to social inclusion and strongly linked to health outcomes. Thus, improving literacy is important for lifelong health promotion. Poverty, inadequate hearing, speech and vision and learning disabilities may challenge literacy development. In our review, we explore these topics and suggest recommendations to: Mitigate the Effects of Poverty, Access Comprehensive Medical Assessments, Promote Early Childhood Education and Advocate for Early Intervention and Remediation Programs.

Early intervention for children at risk for reading disabilities: The impact of grade at intervention and individual differences on intervention outcomes

Across multiple schools in three sites, the impact of grade-at-intervention was evaluated for children at risk or meeting criteria for reading disabilities. A multiple-component reading intervention with demonstrated efficacy was offered to small groups of children in 1st, 2nd, or 3rd grade. In a quasi-experimental design, 172 children received the Triple-Focus Program (PHAST + RAVE-O), and 47 were control participants. Change during intervention and 1-3 years later (6-8 testing points), and the influence of individual differences in predicting outcomes, were assessed using reading and reading-related repeated measures. Intervention children out-performed control children at posttest on all 14 outcomes, with average effect sizes (Cohen's d) on standardized measures of .80 and on experimental measures of 1.69. On foundational word reading skills (standardized measures), children who received intervention earlier, in 1st and 2nd grade, made gains relative to controls almost twice that of children receiving intervention in 3rd grade. At follow-up, the advantage of 1st grade intervention was even clearer: First graders continued to grow at faster rates over the follow-up years than 2nd graders on six of eight key reading outcomes. For some outcomes with metalinguistic demands beyond the phonological, however, a posttest advantage was revealed for 2nd grade Triple participants and for 3rd grade Triple participants relative to controls. Estimated IQ predicted growth during intervention on seven of eight outcomes. Growth during follow-up was predicted by vocabulary and visual sequential memory. These findings provide evidence on the importance of early intensive evidence-based intervention for reading problems in the primary grades.

Working Toward a More Literate World: Reading Intervention Commentary

This issue of New Directions for Child and Adolescent Development summarizes recent and ongoing work to establish evidence-based practices in early reading instruction and intervention and to improve access to and quality of literacy programs in low- and middle-income countries. The authors describe projects of varying sizes and goals, conducted in multiple sites in Africa, the Middle East, Asia, and Latin America. What is immediately striking is the commitment to documenting the efficacy and effectiveness of these programs using wherever possible the methodological standards of intervention science and education research. Often thousands of children and hundreds of schools have been included despite the challenges involved. Data from these projects have informed plans for future programming in these countries, and results from large scale-ups have provided insight into the most important factors necessary for scale-up and sustainability. In this article, I present, in the context of an overview of the sum of these articles, my own thoughts on their importance and implications.

Combined Modality Intervention for ADHD With Comorbid Reading Disorders: A Proof of Concept Study

To evaluate the relative efficacy of two reading programs with and without adjunctive stimulant medication for children with attention-deficit/hyperactivity disorder and comorbid reading disorder (ADHD+RD). Sixty-five children (7-11 years in age) were assigned randomly to one of three intensive remedial academic programs (phonologically or strategy-based reading instruction, or general academic strategy and social skills training) in combination with either immediate-release methylphenidate or placebo. Multiple-blind procedures were used for medication/placebo, given twice daily. Children received 35 hours of instruction in 10 weeks, taught by a trained teacher in a separate school classroom, in small matched groups of 2 to 3. Children's behavior and reading abilities were assessed before and after intervention. Stimulant medication produced expected beneficial effects on hyperactive/impulsive behavioral symptoms (reported by classroom teachers) but none on reading. Children receiving a reading program showed greater gains than controls on multiple standardized measures of reading and related skills (regardless of medication status). Small sample sizes precluded interpretation of possible potentiating effects of stimulant medication on reading skills taught in particular reading programs. Intensive reading instruction, regardless of treatment with stimulant medication, may be efficacious in improving reading problems in children with ADHD+RD and warrants further investigation in a large-scale study.

The Woodcock Reading Mastery Test

This study examined the magnitude of differences in standard scores, convergent validity, and concurrent validity when an individual’s performance was gauged using the revised and the normative update (Woodcock, 1998) editions of the Woodcock Reading Mastery Test in which the actual test items remained identical but norms have been updated. From three metropolitan areas, 899 first to third grade students referred by their teachers for a reading intervention program participated. Results showed the inverse Flynn effect, indicating systematic inflation averaging 5 to 9 standard score points, regardless of gender, IQ, city site, or ethnicity, when calculated using the updated norms. Inflation was greater at lower raw score levels. Implications for using the updated norms for identifying children with reading disabilities and changing norms during an ongoing study are discussed.

Executive Functions Contribute Uniquely to Reading Competence in Minority Youth

Competent reading requires various skills beyond those for basic word reading (i.e., core language skills, rapid naming, phonological processing). Contributing "higher-level" or domain-general processes include information processing speed and executive functions (working memory, strategic problem solving, attentional switching). Research in this area has relied on largely Caucasian samples, with limited representation of children from racial or ethnic minority groups. This study examined contributions of executive skills to reading competence in 761 children of minority backgrounds. Hierarchical linear regressions examined unique contributions of executive functions (EF) to word reading, fluency, and comprehension. EF contributed uniquely to reading performance, over and above reading-related language skills; working memory contributed uniquely to all components of reading; while attentional switching, but not problem solving, contributed to isolated and contextual word reading and reading fluency. Problem solving uniquely predicted comprehension, suggesting that this skill may be especially important for reading comprehension in minority youth. Attentional switching may play a unique role in development of reading fluency in minority youth, perhaps as a result of the increased demand for switching between spoken versus written dialects. Findings have implications for educational and clinical practice with regard to reading instruction, remedial reading intervention, and assessment of individuals with reading difficulty.

Exploring Differential Effects Across Two Decoding Treatments on Item-Level Transfer in Children with Significant Word Reading Difficulties: A New Approach for Testing Intervention Elements

In English, gains in decoding skill do not map directly onto increases in word reading. However, beyond the Self-Teaching Hypothesis (Share, 1995), little is known about the transfer of decoding skills to word reading. In this study, we offer a new approach to testing specific decoding elements on transfer to word reading. To illustrate, we modeled word-reading gains among children with reading disability (RD) enrolled in Phonological and Strategy Training (PHAST) or Phonics for Reading (PFR). Conditions differed in sublexical training with PHAST stressing multi-level connections and PFR emphasizing simple grapheme-phoneme correspondences. Thirty-seven children with RD, 3^rd - 6^th grade, were randomly assigned 60 lessons of PHAST or PFR. Crossed random-effects models allowed us to identify specific intervention elements that differentially impacted word-reading performance at posttest, with children in PHAST better able to read words with variant vowel pronunciations. Results suggest that sublexical emphasis influences transfer gains to word reading.

Multiple-component remediation for developmental reading disabilities: IQ, socioeconomic status, and race as factors in remedial outcome

Results from a controlled evaluation of remedial reading interventions are reported: 279 young disabled readers were randomly assigned to a program according to a 2 × 2 × 2 factorial design (IQ, socioeconomic status [SES], and race). The effectiveness of two multiple-component intervention programs for children with reading disabilities (PHAB + RAVE-O; PHAB + WIST) was evaluated against alternate (CSS, MATH) and phonological control programs. Interventions were taught an hour daily for 70 days on a 1:4 ratio at three different sites. Multiple-component programs showed significant improvements relative to control programs on all basic reading skills after 70 hours and at 1-year follow-up. Equivalent gains were observed for different racial, SES, and IQ groups. These factors did not systematically interact with program. Differential outcomes for word identification, fluency, comprehension, and vocabulary were found between the multidimensional programs, although equivalent long-term outcomes and equal continued growth confirmed that different pathways exist to effective reading remediation.

Evaluating the efficacy of remediation for struggling readers in high school

Preliminary efficacy data are reported for a research-based reading intervention designed for struggling readers in high school. PHAST PACES teaches (a) word identification strategies, (b) knowledge of text structures, and (c) reading comprehension strategies. In a quasi-experimental design, 268 intervention and 83 waiting list control students meeting criteria for reading disability were assessed before and after their semester. After 60 to 70 hours of PHAST PACES instruction, struggling readers demonstrated significant gains on standardized tests of word attack, word reading, and passage comprehension and on experimental measures of letter-sound knowledge and multisyllabic word identification relative to control students. An average effect size of .68 was revealed across these outcome measures. One year follow-up data on 197 PHAST PACES students revealed an average trend to decelerated growth after the intervention, except for passage comprehension outcomes that demonstrated continued growth over follow-up.

A taxometric investigation of developmental dyslexia subtypes

Long-standing issues with the conceptualization, identification and subtyping of developmental dyslexia persist. This study takes an alternative approach to examine the heterogeneity of developmental dyslexia using taxometric classification techniques. These methods were used with a large sample of 671 children ages 6-8 who were diagnosed with severe reading disorders. Latent characteristics of the sample are assessed in regard to posited subtypes with phonological deficits and naming speed deficits, thus extending prior work by addressing whether these deficits embody separate classes of individuals. Findings support separate taxa of dyslexia with and without phonological deficits. Different latent structure for naming speed deficits was found depending on the definitional criterion used to define dyslexia. Non-phonologically based forms of dyslexia showed particular difficulty with naming speed and reading fluency.

Orthographic processing efficiency in developmental dyslexia: an investigation of age and treatment factors at the sublexical level

Reading fluency beyond decoding is a limitation to many children with developmental reading disorders. In the interest of remediating dysfluency, contributing factors need to be explored and understood in a developmental framework. The focus of this study is orthographic processing in developmental dyslexia, and how it may contribute to reading fluency. We investigated orthographic processing speed and accuracy by children identified with dyslexia that were enrolled in an intensive, fluency-based intervention using a timed visual search task as a tool to measure orthographic recognition. Results indicate both age and treatment effects, and delineate a link between rapid letter naming and efficient orthographic recognition. Orthographic efficiency was related to reading speed for passages, but not spelling performance. The role of orthographic learning in reading fluency and remediation is discussed.

Neurocognitive predictors of reading outcomes for children with reading disabilities

This study reports on several specific neurocognitive process predictors of reading outcomes for a sample of 278 children with reading disabilities. Three categories of response (i.e., poor, average, and good) were formed via growth curve models of six reading outcomes. Two nested discriminant function analyses were conducted to evaluate the predictive capability of the following models: (a) an intervention and phonological processing model that included intervention group, phonological awareness, and rapid naming and (b) an additive cognitive neuropsychological model that included measures of memory, visual processes, and cognitive or intellectual functioning. Over and above the substantial explanatory power of the base model, the additive model improved classification of poor and good responders. Several of the cognitive and neuropsychological variables predicted degree of reading outcomes, even after controlling for type of intervention, phonological awareness, and rapid naming.

The Relationship Between Different Measures of Oral Reading Fluency and Reading Comprehension in Second-Grade Students Who Evidence Different Oral Reading Fluency Difficulties

Purpose

The purpose of this study was to examine whether different measures of oral reading fluency relate differentially to reading comprehension performance in two samples of second-grade students: (a) students who evidenced difficulties with nonsense-word oral reading fluency, real-word oral reading fluency, and oral reading fluency of connected text (ORFD), and (b) students who evidenced difficulties only with oral reading fluency of connected text (CTD).

Method

Participants (ORFD, n = 146 and CTD, n = 949) were second-grade students who were recruited for participation in different reading intervention studies. Data analyzed were from measures of nonsense-word oral reading fluency, real-word oral reading fluency, oral reading fluency of connected text, and reading comprehension that were collected at the pre-intervention time point.

Results

Correlational and path analyses indicated that real-word oral reading fluency was the strongest predictor of reading comprehension performance in both samples and across average and poor reading comprehension abilities.

Conclusion

Results of this study indicate that real-word oral reading fluency was the strongest predictor of reading comprehension and suggest that real-word oral reading fluency may be an efficient method for identifying potential reading comprehension difficulties.

Association of reading disabilities with regions marked by acetylated H3 histones in KIAA0319

Reading disabilities (RDs) have been associated with chromosome 6p with recent studies pointing to two genes, DCDC2 and KIAA0319. In this study, markers across the 6p region were tested for association with RD. Our strongest findings were for association with markers in KIAA0319, although with the opposite alleles compared with a previous study. We also found association with markers in VMP, but not with DCDC2. Current evidence indicates that differential regulation of KIAA0319 and DCDC2 contributes to RD, thus we used chromatin immunoprecipitation coupled with genomic tiling arrays (ChIP-chip) to map acetylated histones, a molecular marker for regulatory elements, across a 500 kb genomic region covering the RD locus on 6p. This approach identified several regions marked by acetylated histones that mapped near associated markers, including intron 7 of DCDC2 and the 5' region of KIAA0319. The latter is located within the 70 kb region previously associated with differential expression of KIAA0319. Interestingly, five markers associated with RD in independent studies were also located within the 2.7 kb acetylated region, and six additional associated markers, including the most significant one in this study, were located within a 22 kb haplotype block that encompassed this region. Our data indicates that this putative regulatory region is a likely site of genetic variation contributing to RD in our sample, further narrowing the candidate region.

The KIAA0319-like (KIAA0319L) gene on chromosome 1p34 as a candidate for reading disabilities

A locus on chromosome 1p34-36 (DYX8) has been linked to developmental dyslexia or reading disabilities (RD) in three independent samples. In the current study, we investigated a candidate gene KIAA0319-Like (KIAA0319L) within DYX8, as it is homologous to KIAA0319, a strong RD candidate gene on chromosome 6p (DYX2). Association was assessed by using five tagging single nucleotide polymorphisms in a sample of 291 nuclear families ascertained through a proband with reading difficulties. Evidence of association was found for a single marker (rs7523017; P=0.042) and a haplotype (P=0.031), with RD defined as a categorical trait in a subset of the sample (n=156 families) with a proband that made our criteria for RD. The same haplotype also showed evidence for association with quantitative measures of word-reading efficiency (i.e., a composite score of word identification and decoding; P=0.032) and rapid naming of objects and colors (P=0.047) when analyzed using the entire sample. Although the results from the current study are modestly significant and would not withstand a correction for multiple testing, KIAA0319L remains an intriguing positional and functional candidate for RD, especially when considered alongside the supporting evidence for its homolog KIAA0319 on chromosome 6p. Additional studies in independent samples are now required to confirm these findings.

Interventions for reading difficulties: a comparison of response to intervention by ELL and EFL struggling readers

This article explores whether struggling readers from different primary language backgrounds differ in response to phonologically based remediation. Following random assignment to one of three reading interventions or to a special education reading control program, reading and reading-related outcomes of 166 struggling readers were assessed before, during, and following 105 intervention hours. Struggling readers met criteria for reading disability, were below average in oral language and verbal skills, and varied in English as a first language (EFL) versus English-language learner (ELL) status. The research-based interventions proved superior to the special education control on both reading outcomes and rate of growth. No differences were revealed for children of EFL or ELL status in intervention outcomes or growth during intervention. Oral language abilities at entry were highly predictive of final outcomes and of reading growth during intervention, with greater language impairment being associated with greater growth.

The varieties of pathways to dysfluent reading: comparing subtypes of children with dyslexia at letter, word, and connected text levels of reading

The majority of work on the double-deficit hypothesis (DDH) of dyslexia has been done at the letter and word levels of reading. Key research questions addressed in this study are (a) do readers with different subtypes of dyslexia display differences in fluency at particular reading levels (e.g., letter, word, and connected text)? and (b) do children with dyslexia identified by either low-achievement or ability-achievement discrepancy criteria show similar differences when classified by the DDH? To address these questions, the authors assessed a sample of 158 children with severe reading impairments in second and third grades on an extensive battery and classified them into three reader subtypes using the DDH. The results demonstrated that the three DDH subtypes exhibited differences in fluency at different levels of reading (letter, word, and connected text), underscoring the separate reading profiles of these subtypes and the different possible routes to dysfluency in reading disabilities. Furthermore, the results suggest that the different patterns among DDH subtypes are primarily driven by the ability-achievement discrepancy group. The implications of these findings are discussed for intervention, reading theory, and a more refined understanding of heterogeneity.

Association of the dopamine receptor D1 gene, DRD1, with inattention symptoms in families selected for reading problems

Twin studies have provided evidence for shared genetic influences between attention-deficit/hyperactivity disorder (ADHD) and specific reading disabilities (RD), with this overlap being highest for the inattentive symptom dimension of ADHD. Previously, we found evidence for association of the dopamine receptor D1 gene (DRD1) with ADHD, and with the inattentive symptom dimension in particular. This, combined with evidence for working memory (WM) deficits in individuals with RD or ADHD, and the importance of D1 receptors in attentional processes and WM function, suggests that DRD1 may be a common genetic influence underlying both disorders. Here, in a study of 232 families ascertained through probands with reading problems, we tested for association of the DRD1 gene with RD, as a categorical trait, and with quantitative measures of key reading component skills, WM ability, and inattentive symptoms. Although no associations were found with RD, or with reading component skills or verbal WM, we found evidence for association with inattentive behaviour. Specifically, DRD1 Haplotype 3, the haplotype previously found to be associated with inattentive symptoms in ADHD, is also associated with parent- and teacher-reported symptoms of inattention in this sample selected for reading problems (P=0.023 and 0.004, respectively). Together, the replicated finding of Haplotype 3 association with inattentive symptoms in two independent study samples strongly supports a role for DRD1 in attentional ability. Furthermore, the association of DRD1 with inattention, but not with RD, or the other reading and reading-related phenotypes analysed, suggests that DRD1 contributes uniquely to inattention, without overlap for reading ability.

The relationship among receptive and expressive vocabulary, listening comprehension, pre-reading skills, word identification skills, and reading comprehension by children with reading disabilities

PURPOSE

Some researchers (F. R. Vellutino, F. M. Scanlon, & M. S. Tanzman, 1994) have argued that the different domains comprising language (e.g., phonology, semantics, and grammar) may influence reading development in a differential manner and at different developmental periods. The purpose of this study was to examine proposed causal relationships among different linguistic subsystems and different measures of reading achievement in a group of children with reading disabilities.

METHODS

Participants were 279 students in 2nd to 3rd grade who met research criteria for reading disability. Of those students, 108 were girls and 171 were boys. In terms of heritage, 135 were African and 144 were Caucasian. Measures assessing pre-reading skills, word identification, reading comprehension, and general oral language skills were administered.

RESULTS

Structural equation modeling analyses indicated receptive and expressive vocabulary knowledge was independently related to pre-reading skills. Additionally, expressive vocabulary knowledge and listening comprehension skills were found to be independently related to word identification abilities.

CONCLUSION

Results are consistent with previous research indicating that oral language skills are related to reading achievement (e.g., A. Olofsson & J. Niedersoe, 1999; H. S. Scarborough, 1990). Results from this study suggest that receptive and expressive vocabulary knowledge influence pre-reading skills in differential ways. Further, results suggest that expressive vocabulary knowledge and listening comprehension skills facilitate word identification skills.

Support for EKN1 as the susceptibility locus for dyslexia on 15q21

Dyslexia has been linked to a number of chromosomal regions including 15q. Recently a gene, EKN1, with unknown function in the linked region, was identified via a translocation breakpoint. This gene was further supported as a susceptibility locus by association studies in a Finnish sample. We investigated the possibility of this locus as a susceptibility gene contributing to dyslexia, analyzed as a categorical trait, and analyzed key reading phenotypes as quantitative traits using six polymorphisms including the two previously reported to be associated with dyslexia. In our sample of 148 families identified through a proband with reading difficulties, we found significant evidence for an association to dyslexia analyzed as a categorical trait and found evidence of association to the reading and related processes of phonological awareness, word identification, decoding, rapid automatized naming, language ability, and verbal short-term memory. However, association was observed with different alleles and haplotypes than those reported to be associated in a Finnish sample. These findings provide support for EKN1 as a risk locus for dyslexia and as contributing to reading component processes and reading-related abilities. Based on these findings, further studies of this gene in independent samples are now required to determine the relationship of this gene to dyslexia.

Psychometric stability of nationally normed and experimental decoding and related measures in children with reading disability

Achievement and cognitive tests are used extensively in the diagnosis and educational placement of children with reading disabilities (RD). Moreover, research on scholastic interventions often requires repeat testing and information on practice effects. Little is known, however, about the test-retest and other psychometric properties of many commonly used measures within the beginning reader population, nor are these nationally normed or experimental measures comparatively evaluated. This study examined the test-retest reliability, practice effects, and relations among a number of nationally normed measures of word identification and spelling and experimental measures of achievement and reading-related cognitive processing tests in young children with significant RD. Reliability was adequate for most tests, although lower than might be ideal on a few measures when there was a lengthy test-retest interval or with the reduced behavioral variability that can be seen in groups of beginning readers. Practice effects were minimal. There were strong relations between nationally normed measures of decoding and spelling and their experimental counterparts and with most measures of reading-related cognitive processes. The implications for the use of such tests in treatment studies that focus on beginning readers are discussed.

Relation between Kaufman Brief Intelligence Test and WISC-III scores of children with RD

Concurrent validity of the Kaufman Brief Intelligence Test (K-BIT) with the Wechsler Intelligence Scale for Children-Third Edition (WISC-III) was evaluated, as well as the K-BIT's accuracy as a predictor of WISC-III scores, in a sample of young children with reading disabilities. The two measures were administered to 65 children from Atlanta, Boston, and Toronto who ranged from 6-5 to 7-11 years of age at testing. Correlations between the verbal, nonverbal, and composite scales of the K-BIT and WISC-III were .60, .48, and .63, respectively. Mean K-BIT scores ranged from 1.2 to 5.0 points higher than the corresponding WISC-III scores. Standard errors of estimation ranged from 10.0 to 12.3 points. In individual cases, K-BIT scores can underestimate or overestimate WISC-III scores by as much as 25 points. Results suggest caution against using the K-BIT exclusively for placement and diagnostic purposes with young children with reading disabilities if IQ scores are required.

Putting struggling readers on the PHAST track: a program to integrate phonological and strategy-based remedial reading instruction and maximize outcomes

PHAST (for Phonological and Strategy Training) is a research-based remedial reading program that attempts to capitalize upon current research on reading disabilities and their remediation. The focus of the program is on the primary obstacles to word identification learning and independent decoding that most disabled readers face and the steps necessary to help these children achieve independent reading skills. A framework of phonologically based remediation was used as a foundation upon which a set of flexible and effective word identification strategies were scaffolded in an integrated developmental sequence. The program uses a combination of direct instruction and dialogue-based metacognitive training, with the pedagogical emphasis shifting from an initial direct instruction, remedial focus to increasingly metacognitive-strategy-based methods. A continuum of intervention over 70 hours provides both (a) remediation of the basic phonological awareness and letter-sound-learning deficits of disabled readers and (b) specific training of five word identification strategies that offer different approaches to the decoding of unfamiliar words and exposure to different levels of subsyllabic segmentation. Explicit instruction in the application and monitoring of multiple word identification strategies and their application to text-reading activities continues throughout the PHAST Program. PHAST training provides the disabled reader with the opportunity to become a flexible reader who approaches new words in or out of context with multiple strategies and has the ability to evaluate the success of their application. The PHAST Program was developed following the controlled evaluation of its components in laboratory classroom settings and recent positive results from their sequential combination. PHAST represents a new integrated approach to programming in this area using instructional components that have already demonstrated their efficacy with children with severe reading disabilities.

Remediating the core deficits of developmental reading disability: a double-deficit perspective

The double-deficit hypothesis (Wolf, 1997; Wolf & Bowers, 1999, this issue) contends that deficits in phonological awareness and deficits in visual naming speed represent two independent causal impediments to reading acquisition for children with developmental reading disabilities (RD). One hundred and sixty-six children with severe RD from 7 to 13 years of age were classified into three deficit subgroups according to a double-deficit framework. A total of 140 children with RD, 84% of the sample, were classified; 54% demonstrated a double deficit (DD), 22% a phonological deficit only (PHON), and 24% a visual-naming speed deficit only (VNS). Diagnostic test profiles highlighted the joint contributions of the two core deficits in depressing written language acquisition. The children in the DD group were more globally impaired than those in the other subgroups, and the VNS group children were the highest achieving and most selectively impaired readers. Following 35 hours of word identification training, sizable gains and significant generalization of training effects were achieved by all subgroups. A metacognitive phonics program resulted in greater generalized effects across the domain of real English words, and a phonological training program produced superior outcomes within the phonological processing domain. The greatest non-word reading gains were achieved by children with only phonological deficits.

Training and transfer-of-learning effects in disabled and normal readers: evidence of specific deficits

Two experiments were conducted to assess the specificity of training and transfer deficits in disabled readers, aged 7 to 9 years. Forty-eight children (reading disabled, age-matched normal controls, and reading-level-matched normal controls) participated in both a reading and a nonreading (music) acquisition paradigm. Children received instruction in grapheme-phoneme and symbol-note correspondence patterns, respectively. Posttraining tests (one day and one week) following rule training compared performance on trained exemplar items with performance on untrained transfer items. Results revealed that normal readers were able to transfer their rule knowledge in both the reading and nonreading (music) acquisition paradigms, while disabled readers were proficient only in the music task, and thus demonstrated transfer deficits specific to learning printed language. Transfer was optimally facilitated for all readers when training procedures included not only presentation of exemplars, but also cues for rule derivation and explicit statement of pattern invariances.

Text comprehension training for disabled readers: an evaluation of reciprocal teaching and text analysis training programs

We are particularly grateful to Dr. Annemarie Sullivan Palincsar for her helpful advice and generosity in sharing materials, procedures, and sample dialogues for use in the version of Reciprocal Teaching used in the present study. This research was supported by an operating grant to the first author from the Ontario Mental Health Foundation. We gratefully acknowledge the contributions of Janet Hinchley and Karen Steinbach in assisting with data collection and Nancy Benson, Carolyn Kroeber, and Karen Steinbach in assisting with data analysis. We thank Sheila Wroblewski and Rosemary Slyne for their contributions in program development and lesson planning. We are grateful to the Principals and staff of Winona and Jesse Ketchem Schools and the Toronto Board of Education for providing satellite locations and support for our programs. The enthusiasm and efforts of the 46 students enrolled in the present programs, and the cooperation and interest of their parents and teachers, are particularly acknowledged.

Computer speech-based training of literacy skills in neurologically impaired children: a controlled evaluation

Twenty-two reading-disabled children were randomly assigned to one of four training conditions to evaluate the effectiveness of a computer speech-based system for training literacy skills. The sample included 17 children with significant neurological impairment of various etiologies (including spina bifida and hydrocephalus, seizure disorder, brain tumors, cerebral palsy, and head injury) and five developmental dyslexics. The training employed a "talking" computer system that provides synthesized speech feedback during the course of learning. The training conditions included three word recognition and spelling-training programs and a math-training control program. Three different literacy-training procedures were compared, with the size of the trained print-to-sound unit varying as letter-sound (LSD: train-->t/r/ai/n); onset-rhyme (OR: train-->tr/ain) and whole word units (WW: train-->train). All literacy-training groups made significant gains in word recognition and spelling, with the LSD- and OR-trained subjects making the greatest word recognition gains on the words that could be trained with segmented speech feedback (i.e., words with regular spelling-to-sound patterns). All literacy-training groups demonstrated significant transfer on uninstructed rhymes of instructed regular words, with the greatest degree of transfer achieved by the LSD-trained subjects. These findings suggest that the neurologically impaired children were able to profit from instructional procedures that segment the printed word into units corresponding to onsets, rhymes, and phonemes and that this segmentation training may facilitate transfer-of-training for them.

A developmental approach to reading disability: accuracy and speed criteria of normal and deficient reading skill

The constructs of accuracy and speed were adopted as performance criteria against which to define 2 clinical samples of disabled readers. Accuracy-disabled subjects had failed to achieve reliable age-appropriate word recognition skills. Rate-disabled readers were age-appropriate in word recognition accuracy but deficient in reading speed. These disabled readers were compared to fluent normal children selected to be reading at the same level of accuracy as the rate-disabled subjects but at a significantly faster rate. All aspects of the accuracy-disabled subjects' reading systems proved deficient, and these children were less able to learn new sound-symbol associations in a task simulating initial reading acquisition. The rate-disabled subjects exhibited a basic deficit in word recognition speed, compromised accuracy when reading in context, and compromised spelling when competing visual patterns were available. A multidimensional oral language impairment was found to accompany the accuracy disability, while the rate disability appeared restricted to language in its visible form and the naming of visual representations. A visual naming speed impairment was associated with both profiles of deficient reading skill.

A developmental perspective on reading dysfunction: accuracy and rate criteria in the subtyping of dyslexic children

Children referred with specific reading dysfunction were subtyped as accuracy disabled or rate disabled according to criteria developed from an information processing model of reading skill. Multiple measures of oral and written language development were compared for two subtyped samples matched on age, sex, and IQ. The two samples were comparable in reading fluency, reading comprehension, word knowledge, and word retrieval functions. Accuracy disabled readers demonstrated inferior decoding and spelling skills. The accuracy disabled sample proved deficient in their understanding of oral language structure and in their ability to associate unfamiliar pseudowords and novel symbols in a task designed to simulate some of the learning involved in initial reading acquisition. It was suggested that these two samples of disabled readers may be best described with respect to their relative standing along a theoretical continuum of normal reading development.

Sentential structure and the perceptual span in normal reading development

An eye-voice span paradigm was adopted to determine whether children use different aspects of sentence structure to facilitate decoding early in the course of reading development. Eighty-four Grade 1 and Grade 2 children, representing four levels of early reading competence, and 15 skilled adult subjects read from four textual conditions; materials varied in the extent to which the texts were semantically and/or syntactically constrained. The more precocious the young reader, the longer his reported span. The better readers' and the adults' advantage was greater the more linguistically constrained the reading material. These data support a continuous model of reading development and are compatible with an interactive definition of early reading behavior.