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.

Early language intervention improves behavioral adjustment in school: Evidence from a cluster randomized trial.

Oral language skills are critical for psychosocial development and children with language difficulties are more likely than peers to experience behavioral problems. This study investigated the effects of an oral language intervention on behavioral adjustment. We collected teacher ratings of behavioral adjustment for 1173 children taking part in a cluster randomized trial of the Nuffield Early Language Intervention (NELI) program in 193 primary schools. Ratings were collected before and immediately after the 20-week intervention. Children receiving the language program showed significantly greater improvements than the untreated control group on a latent variable reflecting behavioral adjustment (d = 0.23). However, the improvements in behavioral adjustment for children receiving language intervention were not mediated by improvements in language. We suggest that the improvements in behavioral adjustment are a consequence of the small group and individual teaching sessions in the language intervention program, which emphasizes the need to pay attention and regulate behavior. This emphasis appears to produce generalized improvements in children's behavior regulation outside of the targeted language teaching sessions.

Visual Motion and Decision-Making in Dyslexia: Reduced Accumulation of Sensory Evidence and Related Neural Dynamics.

Children with and without dyslexia differ in their behavioral responses to visual information, particularly when required to pool dynamic signals over space and time. Importantly, multiple processes contribute to behavioral responses. Here we investigated which processing stages are affected in children with dyslexia when performing visual motion processing tasks, by combining two methods that are sensitive to the dynamic processes leading to responses. We used a diffusion model which decomposes response time and accuracy into distinct cognitive constructs, and high-density EEG. Fifty children with dyslexia (24 male) and 50 typically developing children (28 male) 6-14 years of age judged the direction of motion as quickly and accurately as possible in two global motion tasks (motion coherence and direction integration), which varied in their requirements for noise exclusion. Following our preregistered analyses, we fitted hierarchical Bayesian diffusion models to the data, blinded to group membership. Unblinding revealed reduced evidence accumulation in children with dyslexia compared with typical children for both tasks. Additionally, we identified a response-locked EEG component which was maximal over centro-parietal electrodes which indicated a neural correlate of reduced drift rate in dyslexia in the motion coherence task, thereby linking brain and behavior. We suggest that children with dyslexia tend to be slower to extract sensory evidence from global motion displays, regardless of whether noise exclusion is required, thus furthering our understanding of atypical perceptual decision-making processes in dyslexia.SIGNIFICANCE STATEMENT Reduced sensitivity to visual information has been reported in dyslexia, with a lively debate about whether these differences causally contribute to reading difficulties. In this large preregistered study with a blind modeling approach, we combine state-of-the art methods in both computational modeling and EEG analysis to pinpoint the stages of processing that are atypical in children with dyslexia in two visual motion tasks that vary in their requirement for noise exclusion. We find reduced evidence accumulation in children with dyslexia across both tasks, and identify a neural marker, allowing us to link brain and behavior. We show that children with dyslexia exhibit general difficulties with extracting sensory evidence from global motion displays, not just in tasks that require noise exclusion.

Global motion evoked potentials in autistic and dyslexic children: A cross-syndrome approach.

Atypicalities in psychophysical thresholds for global motion processing have been reported in many neurodevelopmental conditions, including autism and dyslexia. Cross-syndrome comparisons of neural dynamics may help determine whether altered motion processing is a general marker of atypical development or condition-specific. Here, we assessed group differences in N2 peak amplitude (previously proposed as a marker of motion-specific processing) in typically developing (n = 57), autistic (n = 29) and dyslexic children (n = 44) aged 6-14 years, in two global motion tasks. High-density EEG data were collected while children judged the direction of global motion stimuli as quickly and accurately as possible, following a period of random motion. Using a data-driven component decomposition technique, we identified a reliable component that was maximal over occipital electrodes and had an N2-like peak at ~160 msec. We found no group differences in N2 peak amplitude, in either task. However, for both autistic and dyslexic children, there was evidence of atypicalities in later stages of processing that require follow up in future research. Our results suggest that early sensory encoding of motion information is unimpaired in dyslexic and autistic children. Group differences in later processing stages could reflect sustained global motion responses, decision-making, metacognitive processes and/or response generation, which may also distinguish between autistic and dyslexic individuals.

A rare missense variant in the ATP2C2 gene is associated with language impairment and related measures.

At least 5% of children present unexpected difficulties in expressing and understanding spoken language. This condition is highly heritable and often co-occurs with other neurodevelopmental disorders such as dyslexia and ADHD. Through an exome sequencing analysis, we identified a rare missense variant (chr16:84405221, GRCh38.p12) in the ATP2C2 gene. ATP2C2 was implicated in language disorders by linkage and association studies, and exactly the same variant was reported previously in a different exome sequencing study for language impairment (LI). We followed up this finding by genotyping the mutation in cohorts selected for LI and comorbid disorders. We found that the variant had a higher frequency in LI cases (1.8%, N = 360) compared with cohorts selected for dyslexia (0.8%, N = 520) and ADHD (0.7%, N = 150), which presented frequencies comparable to reference databases (0.9%, N = 24 046 gnomAD controls). Additionally, we observed that carriers of the rare variant identified from a general population cohort (N = 42, ALSPAC cohort) presented, as a group, lower scores on a range of reading and language-related measures compared to controls (N = 1825; minimum P = 0.002 for non-word reading). ATP2C2 encodes for an ATPase (SPCA2) that transports calcium and manganese ions into the Golgi lumen. Our functional characterization suggested that the rare variant influences the ATPase activity of SPCA2. Thus, our results further support the role of ATP2C2 locus in language-related phenotypes and pinpoint the possible effects of a specific rare variant at molecular level.

Early language screening and intervention can be delivered successfully at scale: evidence from a cluster randomized controlled trial.

BACKGROUND: It is well established that oral language skills provide a critical foundation for formal education. This study evaluated the effectiveness of the Nuffield Early Language Intervention (NELI) programme in ameliorating language difficulties in the first year of school when delivered at scale. METHODS: We conducted a cluster randomized controlled trial (RCT) in 193 primary schools (containing 238 Reception classrooms). Schools were randomly allocated to either a 20-week oral language intervention or a business-as-usual control group. All classes (N = 5,879 children) in participating schools were screened by school staff using an automated App to assess children's oral language skills. Screening identified 1,173 children as eligible for language intervention: schools containing 571 of these children were allocated to the control group and 569 to the intervention group. RESULTS: Children receiving the NELI programme made significantly larger gains than the business-as-usual control group on a latent variable reflecting standardized measures of language ability (d = .26) and on the school-administered automated assessment of receptive and expressive language skills (d = .32). The effects of intervention did not vary as a function of home language background or gender. CONCLUSIONS: This study provides strong evidence for the effectiveness of a school-based language intervention programme (NELI) delivered at scale. These findings demonstrate that language difficulties can be identified by school-based testing and ameliorated by a TA delivered intervention; this has important implications for educational and social policy.

Annual Research Review: Reading disorders revisited - the critical importance of oral language.

This paper discusses research on reading disorders during the period since their classification within the overarching category of neurodevelopmental disorders (Journal of Child Psychology and Psychiatry, 53, 2012, 593). Following a review of the predictors of learning to read across languages, and the role of language skills as critical foundations for literacy, profiles of reading disorders are discussed and putative causal risk factors at the cognitive, biological, and environmental levels of explanation considered. Reading disorders are highly heritable and highly comorbid with disorders of language, attention, and other learning disorders, notably mathematics disorders. The home literacy environment, reflecting gene-environment correlation, is one of several factors that promote reading development and highlight an important target for intervention. The multiple deficit view of dyslexia (Cognition, 101, 2006, 385) suggests that risks accumulate to a diagnostic threshold although categorical diagnoses tend to be unstable. Implications for assessment and intervention are discussed.

Shared storybook reading with children at family risk of dyslexia.

Background: Shared storybook reading is an important context for language learning and often constitutes young children's first encounter with the printed word. The quality of early shared reading interactions is a known predictor of language and reading development, but few studies have examined these interactions in children at family risk of dyslexia. Methods: This exploratory study describes the quality of shared storybook reading between mothers and their 3- to 4-year-old children at family risk of dyslexia (FR; n = 18) in comparison with dyads with no known risk (no-FR; n = 13). Mother-child interactions while sharing a familiar and an unfamiliar storybook were coded for type of extra-textual talk (meaning-related talk at the concrete and abstract levels; print-related talk) and affective quality. Maternal and child language and literacy skills were considered as potential correlates of shared reading quality. Results: The linguistic and affective quality of shared reading was broadly comparable across FR and no-FR dyads, particularly when sharing a book they knew well, with large within-group variation. Mothers contributed more concrete meaning-related talk when introducing an unfamiliar book to their children; children contributed more extra-textual talk overall when sharing a familiar book. Maternal language, but not reading, skills were related to the linguistic quality of shared reading. The affective quality of reading interactions was rated more highly in dyads where mothers and children had stronger language skills. Conclusions: These results suggest that the quality of shared reading does not vary systematically as a function of children's risk of dyslexia but is related to maternal language skills. This finding needs to be replicated in a larger sample in order to better understand the risk and protective factors associated with dyslexia. Highlights: What is already known about this topic The quality of extra-textual talk during shared reading between parents and preschoolers predicts later language and literacy outcomes in typically developing children.The affective quality of early shared reading predicts children's motivation to read independently in later childhood.Children at family risk of dyslexia are more likely than their peers with no family risk to have difficulty learning to read and may show weaknesses in oral language skills. What this paper adds The linguistic and affective quality of shared reading between mothers and preschool children is broadly similar when children are at family risk of dyslexia compared with no family risk.The type and quantity of extra-textual talk contributed by mothers and children appears to differ according to the familiarity of the storybook, but replication of the findings in a larger sample is required.The linguistic and affective quality of shared reading is related to maternal language skills. Implications for theory, policy or practice Shared storybook reading offers rich language learning opportunities for children at family risk of dyslexia.Maternal language skills may be an important determinant of the interactional quality of shared reading.The linguistic and affective quality of shared reading is not clearly associated with maternal reading difficulties.

Language difficulties are a shared risk factor for both reading disorder and mathematics disorder.

Disorders of reading and mathematics co-occur at greater than chance rates, but they are often studied separately. This article reports the reading and arithmetic outcomes at 9 years of age from a longitudinal study of 224 children at high risk for dyslexia. Using a cutoff at the 10th centile, groups of children with reading disorder (RD), mathematics disorder (MD), and comorbid reading disorder and math disorder (RD&MD) were identified. The risk of these disorders was elevated in children selected in preschool with language difficulties or at family risk for dyslexia. There was a high degree of comorbidity between RD and MD, and many cases-particularly in the comorbid group-also reached the diagnostic threshold for developmental language disorder (DLD). On measures of language, phoneme awareness, rapid automatized naming (RAN) digits, and rated inattention, there was a stepwise pattern: RD > MD > RD&MD. Poor language was associated with each disorder and appears to be a cognitive risk factor for RD, MD, and RD&MD. These findings suggest that there are shared genetic risk factors operating for both RD and MD.

Defining and understanding dyslexia: past, present and future.

Dyslexia is a difficulty in learning to decode (read aloud) and to spell. DSM5 classifies dyslexia as one form of neurodevelopmental disorder. Neurodevelopmental disorders are heritable, life-long conditions with early onset. For many years, research on dyslexia proceeded on the basis that it was a specific learning difficulty - specific meaning that the difficulty could not be explained in terms of obvious causes such as sensory problems or general learning difficulties (low IQ). However, the failure to find qualitative differences in reading, and phonological skills, between children with dyslexia and children with more general learning problems led this kind of 'discrepancy' definition to fall from favour. The Rose Review stated that dyslexia can occur across the IQ range and that poor decoding skills require the same kinds of intervention irrespective of IQ. In this paper, we argue that loosening the criteria for dyslexia has influenced common understanding of the condition and led to diagnostic confusion. In the longer term, the use of the term may need to change. Implications for research and practice are discussed.

Screening for the Identification of Oral Language Difficulties in Brazilian Preschoolers: A Validation Study.

Purpose This study aimed to develop and validate a screening questionnaire for the early identification of language difficulties in Brazilian Portuguese-speaking preschool children. Method The article is divided into two studies. In the first study, we reported the theoretical principles that guided the development of the Screening for Identification of Oral Language Difficulties by Preschool Teachers (SIOLD) and tested the validity of its structure. The psychometric properties of the SIOLD were tested using a sample of 754 children attending Year 1 of preschool. Thirty-two teachers coming from eight different schools completed individual questionnaires for all their students. Confirmatory factor analysis was used to assess the validity of the SIOLD. In the second study, we investigated the accuracy of the questionnaire for identifying children with oral language difficulties using a different sample of 100 preschool children. Using receiver operating characteristic and precision recall curves, we assessed the sensitivity and specificity of the SIOLD to identify children who showed impaired language performance in a short battery of tests. Results The SIOLD has been shown to be a valid and accurate questionnaire for assessing the form and content of oral language in preschool children. It showed good accuracy, with sensitivity ranging between .750 and .857 and specificity of .946 for the identification of language difficulties. Among the cases positively identified by the SIOLD as having language difficulties, 54.5% were true cases of language disorders, while 45.5% were false alarms. The combination of these findings shows that the SIOLD overpredicts positive cases but identifies most children with true language disorders and passes most children without language disorders, as required of a good screening test. Conclusions The questionnaire provides a useful tool for enabling Brazilian teachers to refer children with language difficulties to the speech-language services. The theoretical and clinical implications are discussed.

Dyslexia and Developmental Language Disorder: comorbid disorders with distinct effects on reading comprehension.

BACKGROUND: Reading comprehension draws on both decoding and linguistic comprehension, and poor reading comprehension can be the consequence of a deficit in either of these skills. METHODS: Using outcome data from the longitudinal Wellcome Language and Reading Project, we identified three groups of children at age 8 years: children with dyslexia (N = 21) who had deficits in decoding but not oral language, children with Developmental Language Disorder (DLD; N = 38) whose decoding skills were in the normal range, and children who met criteria for both dyslexia and DLD (N = 29). RESULTS: All three groups had reading comprehension difficulties at the ages of 8 and 9 years relative to TD controls though those of the children with dyslexia were mild (relative to TD controls, d = 0.51 at age 8, d = 0.60 at age 8); while the most severe problems were found in the comorbid dyslexia + DLD group (d = 1.79 at age 8, d = 2.06 at age 9) those with DLD also had significant difficulties (d = 1.56 at age 8, d = 1.56 at age 9). CONCLUSIONS: These findings confirm that children with dyslexia or DLD are at-risk for reading comprehension difficulties but for different reasons, because of weak decoding in the case of dyslexia or weak oral language skills in the case of DLD. Different forms of intervention are required for these groups of children, targeted to their particular area(s) of weakness.

Developmental Outcomes for Children at High Risk of Dyslexia and Children With Developmental Language Disorder.

We followed children at family risk of dyslexia and children with preschool language difficulties from age 3½, comparing them with controls (N = 234). At age 8, children were classified as having dyslexia or Developmental Language Disorder (DLD) and compared at earlier time points with controls. Children with dyslexia have specific difficulties with phonology and emergent reading skills in the preschool period, whereas children with DLD, with or without dyslexia, show a wider range of impairments including significant problems with executive and motor tasks. For children with both dyslexia and DLD, difficulties with phonology are generally more severe than those observed in children with dyslexia or DLD alone. Findings confirm that poor phonology is the major cognitive risk factor for dyslexia.

Longitudinal relationships between speech perception, phonological skills and reading in children at high-risk of dyslexia.

Speech perception deficits are commonly reported in dyslexia but longitudinal evidence that poor speech perception compromises learning to read is scant. We assessed the hypothesis that phonological skills, specifically phoneme awareness and RAN, mediate the relationship between speech perception and reading. We assessed longitudinal predictive relationships between categorical speech perception, phoneme awareness, RAN, language, attention and reading at ages 5½ and 6½ years in 237 children many of whom were at high risk of reading difficulties. Speech perception at 5½ years correlated with language, attention, phoneme awareness and RAN concurrently and was a predictor of reading at 6½ years. There was no significant indirect effect of speech perception on reading via phoneme awareness, suggesting that its effects are separable from those of phoneme awareness. Children classified with dyslexia at 8 years had poorer speech perception than age-controls at 5½ years and children with language disorders (with or without dyslexia) had more severe difficulties with both speech perception and attention control. Categorical speech perception tasks tap factors extraneous to perception, including decision-making skills. Further longitudinal studies are needed to unravel the complex relationships between categorical speech perception tasks and measures of reading and language and attention.

Understanding comorbidity of learning disorders: task-dependent estimates of prevalence.

BACKGROUND: Reading disorder (RD) and mathematics disorder (MD) frequently co-occur. However, the exact comorbidity rates differ largely between studies. Given that MD is characterised by high heterogeneity on the symptom level, differences in comorbidity rates may result from different mathematical subskills used to define MD. Comorbidity rates with RD are likely to be higher when MD is measured by mathematical subskills that do not only build on number processing, but also require language (i.e. arithmetic fluency), than when measured by magnitude processing skills. METHODS: The association between literacy, arithmetic fluency and magnitude processing as well as the overlap between deficits in these domains were assessed in a representative sample of 1,454 third Graders. RESULTS: Associations were significantly higher between literacy and arithmetic, than between literacy and magnitude processing. This was also reflected in comorbidity rates: comorbidity rates between literacy and arithmetic deficits were four times higher than expected by chance, whereas comorbidity rates between literacy and magnitude processing deficits did not exceed chance rate. Deficits in the two mathematical subskills showed some overlap, but also revealed dissociations, corroborating the high heterogeneity of MD. Results are interpreted within a multiple-deficit framework and implications for diagnosis and intervention are discussed. CONCLUSIONS: The overlap between RD and MD depends on the subskills used to define MD. Due to shared domain-general factors mathematical subskills that draw on language skills are more strongly associated with literacy than those that do not require language. The findings further indicate that the same symptom, such as deficits in arithmetic, can be associated with different cognitive deficits, a deficit in language skills or a deficit in number processing.

Language Skills, but Not Frequency Discrimination, Predict Reading Skills in Children at Risk of Dyslexia.

This study evaluated the claim that auditory processing deficits are a cause of reading and language difficulties. We report a longitudinal study of 245 children at family risk of dyslexia, children with preschool language impairments, and control children. Children with language impairments had poorer frequency-discrimination thresholds than controls at 5.5 years, but children at family risk of dyslexia did not. A model assessing longitudinal relationships among frequency discrimination, reading, language, and executive function skills showed that frequency discrimination was predicted by executive skills but was not a longitudinal predictor of reading or language skills. Our findings contradict the hypothesis that frequency discrimination is causally related to dyslexia or language impairment and suggest that individuals at risk for dyslexia or who have language impairments may perform poorly on auditory processing tasks because of comorbid attentional difficulties.

Why do children read more? The influence of reading ability on voluntary reading practices.

BACKGROUND: This study investigates the causal relationships between reading and print exposure and investigates whether the amount children read outside school determines how well they read, or vice versa. Previous findings from behavioural studies suggest that reading predicts print exposure. Here, we use twin-data and apply the behaviour-genetic approach of direction of causality modelling, suggested by Heath et al. (), to investigate the causal relationships between these two traits. METHOD: Partial data were available for a large sample of twin children (N = 11,559) and 262 siblings, all enrolled in the Netherlands Twin Register. Children were assessed around 7.5 years of age. Mothers completed questionnaires reporting children's time spent on reading activities and reading ability. Additional information on reading ability was available through teacher ratings and performance on national reading tests. For siblings reading test, results were available. RESULTS: The reading ability of the twins was comparable to that of the siblings and national norms, showing that twin findings can be generalized to the population. A measurement model was specified with two latent variables, Reading Ability and Print Exposure, which correlated .41. Heritability analyses showed that Reading Ability was highly heritable, while genetic and environmental influences were equally important for Print Exposure. We exploited the fact that the two constructs differ in genetic architecture and fitted direction of causality models. The results supported a causal relationship running from Reading Ability to Print Exposure. CONCLUSIONS: How much and how well children read are moderately correlated. Individual differences in print exposure are less heritable than individual differences in reading ability. Importantly, the present results suggest that it is the children's reading ability that determines how much they choose to read, rather than vice versa.

Developmental changes in the cognitive and educational profiles of children and adolescents with 22q11.2 deletion syndrome.

BACKGROUND: 22q11.2 deletion syndrome (22q11DS) is the most common microdeletion syndrome in humans. The presence of learning difficulty is reported in the majority of individuals with 22q11DS, but there is considerable heterogeneity in cognitive and educational profiles and in the age-related changes. METHOD: Verbal, non-verbal and spatial abilities, and educational attainment of 18 children and adolescents with 22q11DS were assessed at two time points 5 years apart. RESULTS: There was a decline in full-scale IQ, with a sharper decline in verbal than non-verbal skills, whereas spatial abilities remained stable over time. Individual profile analysis revealed discrepancies between full-scale IQ and reading skills, suggestive of "hyperlexia," for more than two-thirds of participants. CONCLUSIONS: The relative strength in verbal ability observed in 22q11DS is more apparent when children are younger, and a more even cognitive profile is observed in older children and adolescents. Educational attainments keep pace with development, and literacy skills are globally higher than might be expected from full-scale IQ.

Evaluation of a parent-delivered early language enrichment programme: evidence from a randomised controlled trial.

BACKGROUND: It is widely believed that increasing parental involvement can improve children's educational outcomes although we lack good evidence for such claims. This study evaluated the effectiveness of a parent-delivered early language enrichment programme. METHODS: We conducted a randomised controlled trial (RCT) with 208 preschool children and their parents living in socially diverse areas in the United Kingdom. Families were allocated to an oral language programme (N = 103) or an active control programme targeting motor skills (N = 105). Parents delivered the programmes to their child at home in daily 20-min sessions over 30 weeks of teaching. RESULTS: Children receiving the language programme made significantly larger gains in language (d = .21) and narrative skills (d = .36) than children receiving the motor skills programme at immediate posttest. Effects on language were maintained 6 months later (d = .34), and at this point, the language group also scored higher on tests of early literacy (d values=.35 and .42). There was no evidence that the movement programme improved motor skills. CONCLUSIONS: This study provides evidence for the effectiveness of a parent-delivered language enrichment programme. Further large-scale evaluations of the programme are needed to confirm and extend these findings.

The efficacy of early language intervention in mainstream school settings: a randomized controlled trial.

BACKGROUND: Oral language skills are a critical foundation for literacy and more generally for educational success. The current study shows that oral language skills can be improved by providing suitable additional help to children with language difficulties in the early stages of formal education. METHODS: We conducted a randomized controlled trial with 394 children in England, comparing a 30-week oral language intervention programme starting in nursery (N = 132) with a 20-week version of the same programme starting in Reception (N = 133). The intervention groups were compared to an untreated waiting control group (N = 129). The programmes were delivered by trained teaching assistants (TAs) working in the children's schools/nurseries. All testers were blind to group allocation. RESULTS: Both the 20- and 30-week programmes produced improvements on primary outcome measures of oral language skill compared to the untreated control group. Effect sizes were small to moderate (20-week programme: d = .21; 30-week programme: d = .30) immediately following the intervention and were maintained at follow-up 6 months later. The difference in improvement between the 20-week and 30-week programmes was not statistically significant. Neither programme produced statistically significant improvements in children's early word reading or reading comprehension skills (secondary outcome measures). CONCLUSIONS: This study provides further evidence that oral language interventions can be delivered successfully by trained TAs to children with oral language difficulties in nursery and Reception classes. The methods evaluated have potentially important policy implications for early education.