Individual growth curves were used to test whether the development of children with reading disabilities is best characterized by models of developmental lag or developmental deficit. Developmental ...changes in reading ability were modeled by using 9 yearly longitudinal assessments of a sample of 403 children classified into three groups representing (a) deficient reading achievement relative to IQ expectations (RD-D), (b) deficient reading achievement consistent with IQ expectations (LA), and (c) no reading deficiency (NRI). Using a model of quadratic growth to a plateau, the age and level at which reading scores plateaued were estimated for each child. Reading-disabled children differed on average from nondisabled children in the level but not in the age at which reading skills plateaued. The RD-D and LA groups did not differ in reading plateau or age at plateau. The subgroup of RD-D children scoring below the 25th percentile in reading differed from LA children only in reading plateau. Results suggest that the developmental course of reading skills in children with reading disability is best characterized by deficit as opposed to lag models. In addition, no support for the validity of classifications of reading disability based on IQ discrepancies was apparent.
Neural Mechanisms in Dyslexia Shaywitz, Sally E.; Mody, Maria; Shaywitz, Bennett A.
Current directions in psychological science : a journal of the American Psychological Society,
12/2006, Letnik:
15, Številka:
6
Journal Article
Recenzirano
Within the last two decades, evidence from many laboratories has converged to indicate the cognitive basis for dyslexia: Dyslexia is a disorder within the language system and, more specifically, ...within a particular subcomponent of that system, phonological processing. Converging evidence from a number of laboratories using functional brain imaging indicates that there is a disruption of left-hemisphere posterior neural systems in child and adult dyslexic readers when they perform reading tasks. The discovery of a disruption in the neural systems serving reading has significant implications for the acceptance of dyslexia as a valid disorder--a necessary condition for its identification and treatment. Brainimaging findings provide, for the first time, convincing, irrefutable evidence that what has been considered a hidden disability is "real," and these findings have practical implications for the provision of accommodations, a critical component of management for older children and young adults attending postsecondary and graduate programs. The utilization of advances in neuroscience to inform educational policy and practices provides an exciting example of translational science being used for the public good.
We examine the dilemmas faced by a medical student with dyslexia who wonders whether he should "out" himself to faculty to receive the accommodations entitled by federal law. We first discuss ...scientific evidence on dyslexia's prevalence, unexpected nature, and neurobiology. We then examine the experiences of medical students who have revealed their dyslexia to illustrate the point that, far too often, attending physicians who know little about dyslexia can misperceive the motives or behavior of students with dyslexia. Because ignorance and misperception of dyslexia can result in bias against students with dyslexia, we strongly recommend a mandatory course for faculty that provides a basic scientific and clinical overview of dyslexia to facilitate greater understanding of dyslexia and support for students with dyslexia.
We systematically assessed the relationships between growth of four components of verbal ability—Information, Similarities, Vocabulary, and Comprehension subtests of the Wechsler Intelligence ...Scale–Revised—and longitudinal growth from Grades 1 to 9 of the Woodcock–Johnson Psycho-Educational Battery Passage Comprehension subtest while controlling for Word Identification and Word Attack, using multilevel growth models on a sample of 414 children. Growth was assessed over all grades (1-9), and separately for early grades (1-5) and later grades (5-9). Over all grades, growth in Word Identification had a substantial standardized loading to Passage Comprehension, and all four verbal abilities had smaller, but significant standardized loadings to Passage Comprehension (p < .05), with Information and Vocabulary having slightly higher loadings than Similarities and Comprehension. For early grades, results were similar to the overall results, with the exception of Vocabulary, which had a nonsignificant loading to Passage Comprehension. For later grades, Word Identification again had the largest, but substantially smaller standardized loading on Passage Comprehension and standardized loadings of all four verbal abilities were statistically significant with Vocabulary and Wechsler Intelligence Scale for Children–Revised (WISC-R) Comprehension having appreciably higher loadings than in the previous analyses. Conversation- and interaction-based intervention and instruction in oral language in general, and vocabulary in particular throughout early childhood and continuing throughout the school years, combined with evidence-based instruction that systematically develops the skills of phonologic awareness, decoding, word reading, fluency, and comprehension in school, may provide a pathway to reducing the achievement gap in reading.
Dyslexia is now widely believed to be a biologically based disorder that is distinct from other, less specific reading problems. According to this view, reading ability is considered to follow a ...bimodal distribution, with dyslexia as the lower mode. We hypothesized that, instead, reading ability follows a normal distribution, with dyslexia at the lower end of the continuum.
We used data from the Connecticut Longitudinal Study, a sample survey of 414 Connecticut children who entered kindergarten in 1983 and were followed as a longitudinal cohort. Dyslexia was defined in terms of a discrepancy score, which represents the difference between actual reading achievement and achievement predicted on the basis of measures of intelligence. Data were available from intelligence tests administered in grades 1, 3, and 5 and achievement tests administered yearly in grades 1 through 6. For each child there were 108 possible discrepancy scores (3 x 3 years x 2 x 6 years) based on combinations of the ability scores (full-scale, verbal, and performance IQ) in each of three years and two achievement scores (reading and mathematics) in each of six years. We demonstrated that each of the discrepancy scores followed a univariate normal distribution and that the interrelation of two different discrepancy scores followed a bivariate normal distribution. At most, only 9 of 108 discrepancy scores (8.3 percent) and 171 of 3402 pairs of discrepancy scores (5.0 percent) were significantly different (at the 5 percent level) from the expected scores--well within the expected values for data with univariate and bivariate normal distributions, respectively. We also examined the stability of dyslexia over time. The normal-distribution model predicted (and the data indicated) that only 7 of the 25 children (28 percent) classified as having dyslexia in grade 1 would also be classified as having dyslexia in grade 3.
Reading difficulties, including dyslexia, occur as part of a continuum that also includes normal reading ability. Dyslexia is not an all-or-none phenomenon, but like hypertension, occurs in degrees. The variability inherent in the diagnosis of dyslexia can be both quantified and predicted with use of the normal-distribution model.
We studied error-related negativity (ERN) and error positivity (Pe) during a discrimination task in 319 unmedicated children divided into subtypes of ADHD (Not-ADHD/inattentive/combined), learning ...disorder (Not-LD/reading/math/reading
+
math), and oppositional defiant disorder. Response-locked ERPs contained a frontocentral ERN and posterior Pe. Error-related negativity and positivity exhibited larger amplitude and later latency than corresponding waves for correct responses matched on reaction time. ADHD did not affect performance on the task. The ADHD/combined sample exceeded controls in ERN amplitude, perhaps reflecting patients’ adaptive monitoring efforts. Compared with controls, subjects with reading disorder and reading
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math disorder performed worse on the task and had marginally more negative correct-related negativities. In contrast, Pe/Pc was smaller in children with reading
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math disorder than among subjects with reading disorder and Not-LD participants; this nonspecific finding is not attributable to error processing. The results reflect anomalies in error processing in these disorders but further research is needed to address inconsistencies in the literature.
Abstract Objective: This study assessed the efficacy of atomoxetine on attention-deficit/hyperactivity disorder (ADHD) symptoms in children and adolescents having ADHD with comorbid dyslexia (ADHD+D) ...and the effects of the treatment on reading measures.
The analyses in this report used data from a study designed to examine the effects of a nonstimulant pharmacological agent, atomoxetine, on reading in children with ADHD+D. Patients ages 10-16 years with ADHD or ADHD+D received open-label atomoxetine for 16 weeks. The ADHD Rating Scale (ADHD-RS) and reading subtests of the Kaufman Test of Educational Achievement (K-TEA) were assessed. Changes in ADHD symptoms and reading scores were also analyzed by ADHD subtype. Treatment effect sizes and correlations between changes in ADHDRS and K-TEA scores were calculated.
After atomoxetine treatment, both ADHD and ADHD+D patient groups showed significant reduction in ADHD symptom and improvements in K-TEA reading scores. The range of treatment effect sizes on K-TEA scores was 0.35-0.53 for the ADHD group and 0.50-0.62 for the ADHD+D group. Pearson's correlation coefficients revealed only a few weak correlations between changes in ADHD symptoms and reading scores, regardless of diagnostic group.
ADHD symptoms and K-TEA reading scores improved for both the ADHD and ADHD+D groups following atomoxetine treatment. Correlation analyses indicate that improvements in reading outcomes cannot be explained by a reduction of ADHD symptoms alone. These findings support further exploration of the potential effects of atomoxetine on reading in children with ADHD and dyslexia or dyslexia alone.
Considerable controversy surrounds the issue of whether estrogen influences cognitive function in postmenopausal women, and the results are far from consistent. For the most part, the cognitive ...processes studied have involved memory; to our knowledge, no previous studies have specifically examined the effects of estrogen on women's reading ability.
To investigate reading and short-term memory in postmenopausal women treated with conjugated equine estrogens, we carried out a randomized, double-blind, placebo-controlled trial of 21 days in 60 midlife, postmenopausal women aged 32.8 to 64.9 years (mean 51.2 years, SD 5.0 years). Women were evaluated for oral reading measured by Gray Oral Reading Tests (third edition) and for verbal memory using immediate and delayed recall on the Logical Memory and Paired Associate Learning subtests of the Wechsler Memory Scale and by a Sentence Span task.
The group receiving daily treatment with conjugated equine estrogens (Premarin, 1.25 mg; Wyeth-Ayerst Labs, Philadelphia, PA, USA) showed better oral reading and verbal memory performance than the placebo group.
Estrogen may have positive effects on oral reading and verbal memory in midlife, postmenopausal women.
Using functional magnetic resonance imaging we examined three important dimensions of attentional control (selective attention, divided attention, and executive function) in 25 neurologically normal, ...right-handed men and women, using tasks involving the perception and processing of printed words, spoken words, or both. In the context of language-processing manipulations: selective attention resulted in increased activation at left hemisphere parietal sites as well as at inferior frontal sites, divided attention resulted in additional increases in activation at these same left hemisphere sites and was also uniquely associated with increased activation of homologous sites in the right hemisphere, and executive function (measured during a complex task requiring sequential decision-making) resulted in increased activation at frontal sites relative to all other conditions. Our findings provide support for the belief that specific functional aspects of attentional control in language processing involve widely distributed but distinctive cortical systems, with mechanisms associated with the control of perceptual selectivity involving primarily parietal and inferior frontal sites and executive function engaging specific sites in frontal cortex.
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