Objectives To determine if differences between dyslexic and typical readers in their reading scores and verbal IQ are evident as early as first grade and whether the trajectory of these differences ...increases or decreases from childhood to adolescence. Study design The subjects were the 414 participants comprising the Connecticut Longitudinal Study, a sample survey cohort, assessed yearly from 1st to 12th grade on measures of reading and IQ. Statistical analysis employed longitudinal models based on growth curves and multiple groups. Results As early as first grade, compared with typical readers, dyslexic readers had lower reading scores and verbal IQ, and their trajectories over time never converge with those of typical readers. These data demonstrate that such differences are not so much a function of increasing disparities over time but instead because of differences already present in first grade between typical and dyslexic readers. Conclusions The achievement gap between typical and dyslexic readers is evident as early as first grade, and this gap persists into adolescence. These findings provide strong evidence and impetus for early identification of and intervention for young children at risk for dyslexia. Implementing effective reading programs as early as kindergarten or even preschool offers the potential to close the achievement gap.
The outcome in adolescence of children diagnosed as dyslexic during the early years of school was examined in children prospectively identified in childhood and continuously followed to young ...adulthood. This sample offers a unique opportunity to investigate a prospectively identified sample of adolescents for whom there is no question of the childhood diagnosis and in whom highly analytic measures of reading and language can be administered in adolescence.
Children were recruited from the Connecticut Longitudinal Study, a cohort of 445 children representative of those children entering public kindergarten in Connecticut in 1983. Two groups were selected when the children were in grade 9: children who met criteria for persistent reading disability in grades 2 through 6 (persistently poor readers PPR; n = 21) and a comparison group of nondisabled children, subdivided into average readers (n = 35) and superior readers (n = 39). In grade 9, each child received a comprehensive assessment of academic, language, and other cognitive skills.
Measures of phonological awareness (but not orthographic awareness) were most significant in differentiating the 3 reading groups, with smaller contributions from measures of word finding and digit-span. Academic measures that best separated good from poor readers were decoding and spelling, whereas measures of math and reading comprehension did not. Measures of phonological awareness, followed next by teacher rating of academic skills were the best predictors of decoding, reading rate, and reading accuracy. In contrast, the best predictor of reading comprehension was word finding, with digit span and socioeconomic status also contributing significantly. Using a growth curve model (quadratic model of growth to a plateau) all 3 groups demonstrated similar patterns of growth over time, with the superior group outperforming the average group, and the average group outperforming the PPR group. There was no evidence that the children in the PPR group catch up in their reading skills.
Deficits in phonological coding continue to characterize dyslexic readers even in adolescence; performance on phonological processing measures contributes most to discriminating dyslexic and average readers, and average and superior readers as well. These data support and extend the findings of previous investigators indicating the continuing contribution of phonological processing to decoding words, reading rate, and accuracy and spelling. Children with dyslexia neither spontaneously remit nor do they demonstrate a lag mechanism for catching up in the development of reading skills. In adolescents, the rate of reading as well as facility with spelling may be most useful clinically in differentiating average from poor readers.
Background: Converging evidence indicates a functional disruption in the neural systems for reading in adults with dyslexia. We examined brain activation patterns in dyslexic and nonimpaired children ...during pseudoword and real-word reading tasks that required phonologic analysis (i.e., tapped the problems experienced by dyslexic children in sounding out words).
Methods: We used functional magnetic resonance imaging (fMRI) to study 144 right-handed children, 70 dyslexic readers, and 74 nonimpaired readers as they read pseudowords and real words.
Results: Children with dyslexia demonstrated a disruption in neural systems for reading involving posterior brain regions, including parietotemporal sites and sites in the occipitotemporal area. Reading skill was positively correlated with the magnitude of activation in the left occipitotemporal region. Activation in the left and right inferior frontal gyri was greater in older compared with younger dyslexic children.
Conclusions: These findings provide neurobiological evidence of an underlying disruption in the neural systems for reading in children with dyslexia and indicate that it is evident at a young age. The locus of the disruption places childhood dyslexia within the same neurobiological framework as dyslexia, and acquired alexia, occurring in adults.
A range of neurobiological investigations shows a failure of left hemisphere posterior brain systems to function properly during reading in children and adults with reading disabilities. Such ...evidence of a disruption in the normal reading pathways provides a neurobiological target for reading interventions. In this study, we hypothesized that the provision of an evidence-based, phonologically mediated reading intervention would improve reading fluency and the development of the fast-paced occipitotemporal systems serving skilled reading.
Functional magnetic resonance imaging was used to study the effects of a phonologically based reading intervention on brain organization and reading fluency in 77 children aged 6.1–9.4 years (49 with reading disability and 28 control subjects). Children comprised three experimental groups: experimental intervention (
n = 37), community intervention (
n = 12), and community control subjects (
n = 28).
Immediately after the year-long intervention, children taught with the experimental intervention had made significant gains in reading fluency and demonstrated increased activation in left hemisphere regions, including the inferior frontal gyrus and the middle temporal gyrus; 1 year after the experimental intervention had ended these children were activating bilateral inferior frontal gyri and left superior temporal and occipitotemporal regions.
These data indicate that the nature of the remedial educational intervention is critical to successful outcomes in children with reading disabilities and that the use of an evidence-based phonologic reading intervention facilitates the development of those fast-paced neural systems that underlie skilled reading.
This study examined whether and how two groups of young adults who were poor readers as children (a relatively compensated group and a group with persistent reading difficulties) differed from ...nonimpaired readers and if there were any factors distinguishing the compensated from persistently poor readers that might account for their different outcomes.
Using functional magnetic resonance imaging, we studied three groups of young adults, ages 18.5–22.5 years, as they read pseudowords and real words: 1) persistently poor readers (PPR;
n = 24); 2) accuracy improved (compensated) readers (AIR;
n = 19); and 3) nonimpaired readers (NI,
n = 27).
Compensated readers, who are accurate but not fluent, demonstrate a relative underactivation in posterior neural systems for reading located in left parietotemporal and occipitotemporal regions. Persistently poor readers, who are both not fluent and less accurate, activate posterior reading systems but engage them differently from nonimpaired readers, appearing to rely more on memory-based rather than analytic word identification strategies.
These findings of divergent neural outcomes as young adults are both new and unexpected and suggest a neural basis for reading outcomes of compensation and persistence in adults with childhood dyslexia.
Recent studies have suggested that attention deficit hyperactivity disorder (ADHD) is associated with abnormalities in basal ganglia and prefrontal cortical functioning. However, these studies have ...primarily relied upon cognitive tasks that reflect impulse control rather than attentional mechanisms.
The authors used functional magnetic resonance imaging to investigate the neural correlates of selective and divided attention in a randomized, double-blind, placebo-controlled pharmacological challenge with methylphenidate in 15 adolescents with ADHD (ages 14-17), eight adolescents with reading disorder (ages 12-17), and four adolescents with both reading disorder and ADHD (ages 14-18) who were scanned during both a methylphenidate and a placebo session. Fourteen healthy comparison subjects (ages 12-20) who were not given methylphenidate served as the primary comparison group.
During the divided attention task, unmedicated subjects with ADHD or reading disorder recruited the left ventral basal ganglia significantly less than the healthy comparison subjects. Methylphenidate led to an increase in activation in this region but had no effect on task performance. Subjects with ADHD also recruited the middle temporal gyrus significantly less than the comparison subjects, but methylphenidate did not have a direct effect on activation in this region.
These results suggest that ADHD is associated with abnormal processing in attentional networks, with specific dysfunction in striatal circuitry. Methylphenidate may act to normalize activity within this network.
Learning to read requires an awareness that spoken words can be decomposed into the phonologic constituents that the alphabetic characters represent. Such phonologic awareness is characteristically ...lacking in dyslexic readers who, therefore, have difficulty mapping the alphabetic characters onto the spoken word. To find the location and extent of the functional disruption in neural systems that underlies this impairment, we used functional magnetic resonance imaging to compare brain activation patterns in dyslexic and nonimpaired subjects as they performed tasks that made progressively greater demands on phonologic analysis. Brain activation patterns differed significantly between the groups with dyslexic readers showing relative underactivation in posterior regions (Wernicke's area, the angular gyrus, and striate cortex) and relative overactivation in an anterior region (inferior frontal gyrus). These results support a conclusion that the impairment in dyslexia is phonologic in nature and that these brain activation patterns may provide a neural signature for this impairment.
Objective
To examine age‐related changes in the neural systems for reading in nonimpaired and dyslexic children and adolescents.
Methods
Functional magnetic resonance imaging was used to study ...age‐related changes in the neural systems for reading in a cross‐sectional sample of 232 right‐handed children 7 to 18 years of age (113 dyslexic readers and 119 nonimpaired readers) as they read pseudowords.
Results
In nonimpaired readers, systems in the left anterior lateral occipitotemporal area developed with age, whereas systems in the right superior and middle frontal regions decreased. In contrast, in dyslexic readers, systems in the left posterior medial occipitotemporal regions developed with age. Older nonimpaired readers were left lateralized in the anterior lateral occipitotemporal area; there was no difference in asymmetry between younger and older dyslexic readers.
Interpretation
These findings offer a possible neurobiological explanation for the differences in reading acquisition between dyslexic and nonimpaired readers and provide further evidence of the critical role of the left occipitotemporal region in the development of reading. Ann Neurol 2007;61:363–370
Preclinical studies suggest that estrogen affects neural structure and function in mature animals; clinical studies are less conclusive with many, but not all, studies showing a positive influence of ...estrogen on verbal memory in postmenopausal women.
To investigate the effects of estrogen on brain activation patterns in postmenopausal women as they performed verbal and nonverbal working memory tasks.
Randomized, double-blind, placebo-controlled, crossover trial from 1996 through 1998.
Community volunteers tested in a hospital setting.
Forty-six postmenopausal women aged 33 to 61 years (mean SD age, 50.8 4.7 years).
Twenty-one-day treatment with conjugated equine estrogens, 1.25 mg/d, randomly crossed over with identical placebo and a 14-day washout between treatments.
Brain activation patterns measured using functional magnetic resonance imaging during tasks involving verbal and nonverbal working memory.
Treatment with estrogen increased activation in the inferior parietal lobule during storage of verbal material and decreased activation in the inferior parietal lobule during storage of nonverbal material. Estrogen also increased activation in the right superior frontal gyrus during retrieval tasks, accompanied by greater left-hemisphere activation during encoding. The latter pattern represents a sharpening of the hemisphere encoding/retrieval asymmetry (HERA) effect. Estrogen did not affect actual performance of the verbal and nonverbal memory tasks.
Estrogen in a therapeutic dosage alters brain activation patterns in postmenopausal women in specific brain regions during the performance of the sorts of memory function that are called upon frequently during any given day. These results suggest that estrogen affects brain organization for memory in postmenopausal women.
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.
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