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Developmental Science Mar 2022This study focuses on the role of numerous cognitive skills such as phonological awareness (PA), rapid automatized naming (RAN), visual and selective attention, auditory...
This study focuses on the role of numerous cognitive skills such as phonological awareness (PA), rapid automatized naming (RAN), visual and selective attention, auditory skills, and implicit learning in developmental dyslexia. We examined the (co)existence of cognitive deficits in dyslexia and assessed cognitive skills' predictive value for reading. First, we compared school-aged children with severe reading impairment (n = 51) to typical readers (n = 71) to explore the individual patterns of deficits in dyslexia. Children with dyslexia, as a group, presented low PA and RAN scores, as well as limited implicit learning skills. However, we found no differences in the other domains. We found a phonological deficit in 51% and a RAN deficit in 26% of children with dyslexia. These deficits coexisted in 14% of the children. Deficits in other cognitive domains were uncommon and most often coexisted with phonological or RAN deficits. Despite having a severe reading impairment, 26% of children with dyslexia did not present any of the tested deficits. Second, in a group of children presenting a wide range of reading abilities (N = 211), we analysed the relationship between cognitive skills and reading level. PA and RAN were independently related to reading abilities. Other skills did not explain any additional variance. The impact of PA and RAN on reading skills differed. While RAN was a consistent predictor of reading, PA predicted reading abilities particularly well in average and good readers with a smaller impact in poorer readers.
Topics: Aptitude; Awareness; Child; Cognition; Dyslexia; Humans; Phonetics
PubMed: 34448328
DOI: 10.1111/desc.13173 -
NeuroImage. Clinical 2016Meta-analytic studies suggest that dyslexia is characterized by subtle and spatially distributed variations in brain anatomy, although many variations failed to be...
Meta-analytic studies suggest that dyslexia is characterized by subtle and spatially distributed variations in brain anatomy, although many variations failed to be significant after corrections of multiple comparisons. To circumvent issues of significance which are characteristic for conventional analysis techniques, and to provide predictive value, we applied a machine learning technique--support vector machine--to differentiate between subjects with and without dyslexia. In a sample of 22 students with dyslexia (20 women) and 27 students without dyslexia (25 women) (18-21 years), a classification performance of 80% (p < 0.001; d-prime = 1.67) was achieved on the basis of differences in gray matter (sensitivity 82%, specificity 78%). The voxels that were most reliable for classification were found in the left occipital fusiform gyrus (LOFG), in the right occipital fusiform gyrus (ROFG), and in the left inferior parietal lobule (LIPL). Additionally, we found that classification certainty (e.g. the percentage of times a subject was correctly classified) correlated with severity of dyslexia (r = 0.47). Furthermore, various significant correlations were found between the three anatomical regions and behavioural measures of spelling, phonology and whole-word-reading. No correlations were found with behavioural measures of short-term memory and visual/attentional confusion. These data indicate that the LOFG, ROFG and the LIPL are neuro-endophenotype and potentially biomarkers for types of dyslexia related to reading, spelling and phonology. In a second and independent sample of 876 young adults of a general population, the trained classifier of the first sample was tested, resulting in a classification performance of 59% (p = 0.07; d-prime = 0.65). This decline in classification performance resulted from a large percentage of false alarms. This study provided support for the use of machine learning in anatomical brain imaging.
Topics: Adolescent; Adult; Brain; Dyslexia; Female; Humans; Machine Learning; Male; Meta-Analysis as Topic; Multimodal Imaging; Neuropsychological Tests; Young Adult
PubMed: 27114899
DOI: 10.1016/j.nicl.2016.03.014 -
Clinical & Experimental Optometry Jul 2006It has been proposed that magnocellular deficits cause dyslexia through reduced attention. According to one model (Vidyasagar, Clinical and Experimental Optometry 2004;... (Review)
Review
It has been proposed that magnocellular deficits cause dyslexia through reduced attention. According to one model (Vidyasagar, Clinical and Experimental Optometry 2004; 87: 4-10), attention is shifted from letter to letter during fixations and magnocellular deficits are hypothesised to cause reading problems by interfering with the ability to control the attention. The present report points out several problems in this model. 1. It requires dissociation of eye movements and attention, which may be problematic within the framework of reading. 2. There is direct evidence to indicate that reading is not carried out in a letter-to-letter manner during fixations. 3. There are aspects of the visual performance of dyslexic readers, which are difficult to attribute to inattention. 4. There are indications that attentional deficiencies of dyslexic readers are not associated with magnocellular deficits. 5. The evidence for linking magnocellular deficits to dyslexia in general is weak.
Topics: Attention; Dyslexia; Eye Movements; Humans; Reading
PubMed: 16776731
DOI: 10.1111/j.1444-0938.2006.00052.x -
American Family Physician Dec 2006Reading difficulties are common and are associated with poor long-term academic achievement. Evaluation of a child's developmental, educational, and family histories in... (Review)
Review
Reading difficulties are common and are associated with poor long-term academic achievement. Evaluation of a child's developmental, educational, and family histories in conjunction with standardized screening tests (e.g., Ages and Stages Questionnaires, Parents' Evaluation of Developmental Status, Safety Word Inventory and Literacy Screener) can increase recognition of risk factors for reading difficulties. Validated, office-based, standardized screening tests and school-administered standardized achievement tests (e.g., California Achievement Tests, Iowa Tests of Basic Skills, Metropolitan Achievement Tests, Stanford Achievement Test) can be used to assess school-age children with reading difficulties. Reading difficulties in children often are caused by environmental and organic risk factors. However, many children have reading or learning disabilities and will have lifelong difficulties with reading despite adequate intervention. Children with substantial reading difficulties should receive a full educational assessment. There is good evidence that individualized instruction emphasizing increased phonologic awareness can have a favorable long-term effect on academic achievement.
Topics: Child; Dyslexia; Humans; Mass Screening; Phonetics; Prevalence; Remedial Teaching; Risk Factors
PubMed: 17186715
DOI: No ID Found -
Annals of Dyslexia Apr 2018We set out to address the adequacy of dyslexia screening in Dutch and non-western immigrant children, using the Dutch Dyslexia Screening Test (DST-NL) and outcomes of...
We set out to address the adequacy of dyslexia screening in Dutch and non-western immigrant children, using the Dutch Dyslexia Screening Test (DST-NL) and outcomes of the Dutch dyslexia protocol, both of which are susceptible to cultural bias. Using the protocol as standard, we conducted an ROC (Receiver Operating Characteristics) analysis in Dutch and immigrant third, fifth, and seventh graders, combining a cross-sectional and longitudinal design. Sensitivity and specificity increased with grade, but were non-significant for various subtests in the lowest grade, suggesting considerable non-convergence between the two measures. Effective subtests in all grades, presumably not strongly influenced by Cultural Background or Word Lexicon, were One-Minute Reading, Non-Word Reading, and Nonsense Passage Reading. In a multilevel analysis, cultural background, dyslexia diagnosis, parental education, and grade of first assessment were predictors of subtest performance. In a second analysis, Word Lexicon was added as a proxy of knowledge of the Dutch language and culture. After controlling for Word Lexicon, cultural background became significant for most subtests, suggesting the presence of cultural bias. Subtests assessing technical literacy, such as One-Minute-Reading, Non-Word-Reading, One-Minute-Writing, or Two-Minutes-Spelling, showed more convergence between the two assessments. Less-effective subtests were Naming Pictures, Backward Digit Span, and Verbal and Semantic Fluency. It is concluded that the DST-NL and the standard protocol do not show complete convergence, notably in the lower grades in the multilingual pupil group of our cohort, mainly because dyslexia and literacy difficulties are hard to disentangle.
Topics: Bias; Child; Cross-Sectional Studies; Cultural Diversity; Dyslexia; Female; Humans; Language Tests; Literacy; Longitudinal Studies; Male; Mass Screening; Netherlands; Parents; Phonetics; Reading; Semantics
PubMed: 29476315
DOI: 10.1007/s11881-018-0155-0 -
Language, Speech, and Hearing Services... Oct 2019Purpose The purpose of our study was to test the hypotheses (a) that children with dyslexia have spoken word learning deficits primarily related to phonology and (b)...
Purpose The purpose of our study was to test the hypotheses (a) that children with dyslexia have spoken word learning deficits primarily related to phonology and (b) that children with dyslexia and concomitant developmental language disorder (DLD) have word learning deficits related to both phonology and semantic processing when compared to peers with typical development (TD). Method Second-graders with dyslexia ( = 82), concomitant dyslexia and DLD (dyslexia + DLD; = 40), and TD ( = 167) learned names and semantic features for cartoon monsters in 5 carefully controlled word learning tasks that varied phonological and semantic demands. The computer-based tasks were played in 6 different word learning games. We analyzed results using Bayesian statistics. Results In general, the dyslexia + DLD group showed lower accuracy on tasks compared to the dyslexia and TD groups. As predicted, word learning tasks that taxed phonology revealed deficits in the dyslexia group, although there were some exceptions related to visual complexity. Word learning deficits in the dyslexia + DLD group were present in tasks that taxed phonology, semantic processing, or both. Conclusions The dyslexia + DLD group demonstrated word learning deficits across the range of word learning tasks that tapped phonology and semantic processing, whereas the dyslexia group primarily struggled with the phonological aspects of word learning. Supplemental Material https://doi.org/10.23641/asha.9807929.
Topics: Analysis of Variance; Bayes Theorem; Child; Dyslexia; Female; Humans; Language Development Disorders; Language Therapy; Learning; Male; Reading; Semantics; Verbal Learning
PubMed: 31600465
DOI: 10.1044/2019_LSHSS-VOIA-18-0138 -
Research in Developmental Disabilities Oct 2013A number of studies have investigated procedural learning in dyslexia using serial reaction time (SRT) tasks. Overall, the results have been mixed, with evidence of both... (Meta-Analysis)
Meta-Analysis Review
A number of studies have investigated procedural learning in dyslexia using serial reaction time (SRT) tasks. Overall, the results have been mixed, with evidence of both impaired and intact learning reported. We undertook a systematic search of studies that examined procedural learning using SRT tasks, and synthesized the data using meta-analysis. A total of 14 studies were identified, representing data from 314 individuals with dyslexia and 317 typically developing control participants. The results indicate that, on average, individuals with dyslexia have worse procedural learning abilities than controls, as indexed by sequence learning on the SRT task. The average weighted standardized mean difference (the effect size) was found to be 0.449 (CI95: .204, .693), and was significant (p<.001). However, moderate levels of heterogeneity were found between study-level effect sizes. Meta-regression analyses indicated that studies with older participants that used SRT tasks with second order conditional sequences, or with older participants that used sequences that were presented a large number of times, were associated with smaller effect sizes. These associations are discussed with respect to compensatory and delayed memory systems in dyslexia.
Topics: Adult; Child; Dyslexia; Humans; Learning Disabilities; Memory; Reaction Time; Serial Learning
PubMed: 23920029
DOI: 10.1016/j.ridd.2013.07.017 -
Journal of Neurodevelopmental Disorders Nov 2019Dyslexia and Attention-deficit/hyperactivity disorder (ADHD) are highly comorbid neurodevelopmental disorders (estimates of 25-40% bidirectional comorbidity). Previous... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Dyslexia and Attention-deficit/hyperactivity disorder (ADHD) are highly comorbid neurodevelopmental disorders (estimates of 25-40% bidirectional comorbidity). Previous work has identified strong genetic and cognitive overlap between the disorders, but neural overlap is relatively unexplored. This study is a systematic meta-analysis of existing voxel-based morphometry studies to determine whether there is any overlap in the gray matter correlates of both disorders.
METHODS
We conducted anatomic likelihood estimate (ALE) meta-analyses of voxel-based morphometry studies in which individuals with dyslexia (15 studies; 417 cases, 416 controls) or ADHD (22 studies; 898 cases, 763 controls) were compared to typically developing controls. We generated ALE maps for dyslexia vs. controls and ADHD vs. controls using more conservative (p < .001, k = 50) and more lenient (p < .005, k = 50) thresholds. To determine the overlap of gray matter correlates of dyslexia and ADHD, we examined the statistical conjunction between the ALE maps for dyslexia vs. controls and ADHD vs. controls (false discovery rate [FDR] p < .05, k = 50, 5000 permutations).
RESULTS
Results showed largely distinct gray matter differences associated with dyslexia and ADHD. There was no evidence of statistically significant gray matter overlap at our conservative threshold, and only one region of overlap in the right caudate at our more lenient threshold. Reduced gray matter in the right caudate may be relevant to shared cognitive correlates in executive functioning and/or procedural learning. The more general finding of largely distinct regional differences in gray matter between dyslexia and ADHD suggests that other neuroimaging modalities may be more sensitive to overlapping neural correlates, and that current neuroimaging recruitment approaches may be hindering progress toward uncovering neural systems associated with comorbidity.
CONCLUSIONS
The current study is the first to meta-analyze overlap between gray matter differences in dyslexia and ADHD, which is a critical step toward constructing a multi-level understanding of this comorbidity that spans the genetic, neural, and cognitive levels of analysis.
Topics: Attention Deficit Disorder with Hyperactivity; Caudate Nucleus; Comorbidity; Dyslexia; Gray Matter; Humans; Neuroimaging
PubMed: 31752659
DOI: 10.1186/s11689-019-9287-8 -
International Journal of Language &... 2014The term 'specific language impairment' (SLI), in use since the 1980s, describes children with language impairment whose cognitive skills are within normal limits where... (Review)
Review
BACKGROUND
The term 'specific language impairment' (SLI), in use since the 1980s, describes children with language impairment whose cognitive skills are within normal limits where there is no identifiable reason for the language impairment. SLI is determined by applying exclusionary criteria, so that it is defined by what it is not rather than by what it is. The recent decision to not include SLI in DSM-5 provoked much debate and concern from researchers and clinicians.
AIMS
To explore how the term 'specific language impairment' emerged, to consider how disorders, including SLI, are generally defined and to explore how societal changes might impact on use the term.
METHODS & PROCEDURES
We reviewed the literature to explore the origins of the term 'specific language impairment' and present published evidence, as well as new analyses of population data, to explore the validity of continuing to use the term.
OUTCOMES & RESULTS AND CONCLUSIONS & IMPLICATIONS
We support the decision to exclude the term 'specific language impairment' from DSM-5 and conclude that the term has been a convenient label for researchers, but that the current classification is unacceptably arbitrary. Furthermore, we argue there is no empirical evidence to support the continued use of the term SLI and limited evidence that it has provided any real benefits for children and their families. In fact, the term may be disadvantageous to some due to the use of exclusionary criteria to determine eligibility for and access to speech pathology services. We propose the following recommendations. First, that the word 'specific' be removed and the label 'language impairment' be used. Second, that the exclusionary criteria be relaxed and in their place inclusionary criteria be adopted that take into account the fluid nature of language development particularly in the preschool period. Building on the goodwill and collaborations between the clinical and research communities we propose the establishment of an international consensus panel to develop an agreed definition and set of criteria for language impairment. Given the rich data now available in population studies it is possible to test the validity of these definitions and criteria. Consultation with service users and policy-makers should be incorporated into the decision-making process.
Topics: Attention Deficit Disorder with Hyperactivity; Child, Preschool; Comorbidity; Diagnostic and Statistical Manual of Mental Disorders; Dyslexia; Humans; Intelligence; Language Development Disorders; Language Tests; Reference Values; Social Change; Statistics as Topic
PubMed: 25142091
DOI: 10.1111/1460-6984.12102 -
Dyslexia (Chichester, England) May 2022The assumption that statistical learning is affected in dyslexia has generally been evaluated in children and adults with diagnosed dyslexia, not in pre-literate...
The assumption that statistical learning is affected in dyslexia has generally been evaluated in children and adults with diagnosed dyslexia, not in pre-literate children with a family risk (FR) of dyslexia. In this study, four-to-five-year-old FR children (n = 25) and No-FR children (n = 33) completed tasks of emerging literacy (phoneme awareness and RAN). They also performed an online non-adjacent dependency learning (NADL) task, based on the Serial Reaction Time (SRT) task paradigm. Children's accuracy (hits), signal sensitivity (d') and reaction times were measured. The FR group performed marginally more poorly on phoneme awareness and significantly more poorly on RAN than the No-FR group. Regarding NADL outcomes, the results were less straightforward: the data suggested successful statistical learning for both groups, as indicated by the hit and reaction time curves found. However, the FR group was less accurate and slower on the task than the No-FR group. Furthermore, unlike the No-FR group, performance in the FR group varied as a function of the specific stimulus presented. Taken together, these findings fail to show a robust difference in statistical learning between children with and without an FR of dyslexia at preschool age, in line with earlier work on older children and adults with dyslexia.
Topics: Adolescent; Adult; Child; Child, Preschool; Dyslexia; Humans; Learning; Literacy; Reaction Time; Reading
PubMed: 35289019
DOI: 10.1002/dys.1711