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At least 19 recordsLinked to original sources
PubMed2004

Neuroanatomical markers for dyslexia: a review of dyslexia structural imaging studies.

A neuroanatomical description of dyslexia has been elusive, due in part to the complex cognitive nature of dyslexia. People with dyslexia have varying degrees of impairment in reading skills that engage oral and written language (reading) neural networks. Although findings for the inferior parietal lobule, inferior frontal gyrus, and cerebellum have been relatively consistent across studies, these studies also demonstrate that anatomical patterns of results vary according to the reading skills that characterize dyslexia. The number and likelihood of atypical anatomical findings in oral and/or written language systems appears to be related to the pattern of impairments in measures of phonology, orthography, and fluency. A comprehensive neurobiological understanding of dyslexia will depend on studies of dyslexic individuals with homogeneous perceptual, cognitive, and genetic backgrounds.

Biomarkers↗
PubMed2005

Letter form as a constraint for errors in neglect dyslexia and letter position dyslexia.

Does letter-form constrain errors in peripheral dyslexia? In Hebrew, 5 of the 22 letters have two different letter forms, one is used only when the letter occurs in word-final position, the other form is used in initial and middle positions. Is the information on final-forms encoded in the letter identity information and used for word identification, or is it discarded? The current research explored this question through the effect of final vs. non final letter form on the error pattern in neglect dyslexia (neglexia) and letter position dyslexia (LPD). Left word-based neglexia results in errors of omission, substitution and addition of letters in the left side of words, which in Hebrew is the end of the word. We examined whether final letter form blocks the addition of letters to the end of the word and whether omissions of letters after letters in non-final form are avoided. The predominant error type in LPD is migration of letters within words. We tested whether migrations also occur when they cause form change of either final-form letters that move to middle position or middle-form letters that move to final position. These questions were assessed in both acquired and developmental neglexia and LPD. The results indicated a strong effect of final letter-form on acquired neglexia and on acquired and developmental LPD, which almost completely prevented form-changing errors. This effect was not found in developmental neglexia, where words that end in final-form letters were actually more impaired than other words, probably because final-form letters appear only on the neglected side of the word for Hebrew-reading children with left developmental neglexia. These data show that early visuo-orthographic analysis is sensitive to final letter form and that final letter form constrains errors in peripheral dyslexia.

Adult↗
PubMedDate not supplied

Definition and treatment of dyslexia: a report by the Committee on Dyslexia of the Health Council of The Netherlands.

A committee of the Health Council of the Netherlands prepared a report on the definition and treatment of dyslexia at the request of the Minister of Health, Welfare, and Sport (see Note). The Health Council, as charged by the Health Act, is to inform the government on the state of science with respect to public health issues. The Council is entirely funded by the government but otherwise completely independent (an independence guaranteed by law). The committee was formed to answer questions regarding the provisions and funds needed for the treatment of persons with dyslexia, neuropsychological treatment modalities, in particular, and the role of speech and language therapists. Definitive decision making about reimbursement by the Dutch National Health Service for treatment by speech and language therapists in cases of dyslexia was on hold, pending the committee's report. Specific attention was requested for the following aspects: the definition of dyslexia (the characteristic symptoms of this category of developmental language disabilities); the consequences of the proposed definition for indication and treatment; the appropriate methods of treatment; the involvement of several possible professionals (e.g., neuropsychologist, remedial teacher, speech and language therapist), as well as the role of the neurologist during and in relation to the treatment process; and those situations in which treatment should be the responsibility of the health care system. This article summarizes the committee's considerations and conclusions on these different aspects.

Adolescent↗
PubMed2004

Sub-types of deep dyslexia: a case study of central deep dyslexia.

A case study is reported of a female patient (JAH), who following a left middle cerebral artery infarct, presented with the cardinal symptoms of deep dyslexia and deep dysphasia (semantic errors when reading and repeating words aloud, respectively). Detailed assessment revealed impaired performance across modalities for many tasks, but particularly those tasks that depend on an intact store of semantic knowledge. Her acquired dyslexia is best characterised as deep dyslexia of a central sub-type.

Adult↗
PubMed1991

Interventions based on the multiple connections model of reading for developmental dyslexia and acquired deep dyslexia.

This paper deals with intervention strategies for developmental and acquired dyslexia. In Study 1 two alternative strategies for developmental surface dyslexia (dysfunctional connection between the whole word orthographic code and the phonetic or name code) were compared. In both the initial study and replication study, a modification of the selective reminding technique was superior to a traditional multisensory technique in beginning readers, presumably because it facilitated word finding or prelexical access to a phonetic code. In Study 2 an adolescent with acquired deep dyslexia (dysfunctional connection between letter and phonemic codes) who had had his angular gyrus (site of grapheme-phoneme correspondence) surgically removed, recovered reading function after a four-month phonemic analysis training program. Further research is needed to evaluate the efficacy of theory-based intervention strategies in children with developmental reading disorders unrelated to focal lesions and in adults with acquired reading disorders related to focal lesions.

Journal Article↗
PubMed1986

[Dyslexia and late dyslexia and analphabetism from the otologic-audiologic-phoniatric viewpoint].

The special dyslexia in childhood may be interpreted as a functional disorder. Foundation of each treatment is the difference to pseudodyslexia. The exclusion of a conduction hearing loss or sensorineural hard of hearing including the recognition of a verbal communication disturbance should be made regularly. The late dyslexia amongst youth and the illiteracy of adults increases more and more. There should be the integration of otologic-audiologic-phoniatric assessment and a multifaceted diagnosis and treatment concept.

Agraphia↗
PubMed2003

Dyslexia and psychosocial factors. A follow-up study of young Norwegian adults with a history of dyslexia in childhood.

The present study is a follow-up of two different groups of young adults with a history of dyslexia problems in childhood. Group A was drawn from a larger longitudinal study where students were diagnosed with dyslexia at age 10. Group B was recruited at a child psychiatric clinic and also had dyslexic problems. Measures of educational level, life satisfaction and psychosocial factors were applied. The assessment was carried out by means of tests, questionnaires and personal interviews. The results showed lower levels of educational attainment in group B as well as lower satisfaction with health, friends and education compared to group A and a normative group. Both dyslexic groups showed more psychiatric problems than those in the normative sample.

Adolescent↗
PubMed2005

Acquired dyslexia in Spanish: a review and some observations on a new case of deep dyslexia.

Readers and writers of Spanish use an orthography that is highly transparent. It has been proposed that readers of Spanish can rely on grapheme-phoneme correspondences, alone, to access meaning or phonology from print. In recent years, a number of case studies have yielded evidence inconsistent with this idea. We review these studies with particular focus on those that report evidence for reading based on direct lexical mappings between print, orthographic representations, and meaning or phonology. We report a new case of acquired literacy impairment in Spanish, MJ, who presents a pattern of preserved abilities and deficits symptomatic of deep dyslexia. The patient is unable to read nonwords, but can read a substantial number of words. Her reading is characterized by the production of semantic, visual, and derivational errors. We argue that MJ has a deficit in her lexical selection ability, common to both her reading and her naming problems. We propose that MJ, and the other cases we review, demonstrate that lexical reading is adopted by skilled readers even in a transparent language.

Adult↗
PubMedDate not supplied

Sound-symbol learning in children with dyslexia.

This study evaluated the effect of sound-symbol association training on visual and phonological memory in children with a history of dyslexia. Pretests of phonological and visual memory, a sound-symbol training procedure, and phonological and visual memory posttests were administered to children with dyslexia, to children whose dyslexia had been compensated through remedial training, and to age- and reading level-matched comparison groups. Deficits in visual and phonological memory and memory for sound-symbol associations were demonstrated in the dyslexia group. For children with dyslexia and children whose dyslexia had been remediated, the sound-symbol training scores were significantly associated with word and pseudoword reading scores and were significantly lower than those of the comparison groups. Children with dyslexia and children whose dyslexia had been compensated showed significantly less facilitation of phonological memory following the training than did typical readers. Skilled readers showed some reduction in accuracy of visual memory following the training, which may be the result of interference of verbalization with a predominantly visual task. A parallel decrease was not observed in the children with dyslexia, possibly because these children did not use the verbal cues. Children with dyslexia and children whose dyslexia had been compensated seemed to have difficulty encoding the novel sounds in memory. As a result, they derived less phonological memory advantage and less visual memory interference from the training than did typical readers. Children in the compensated dyslexia group scored lower on sound-symbol training than their age peers. In other respects, the scores of these children were equivalent to those of the typically reading comparison groups. Children in the compensated dyslexia group exhibited higher phonological rehearsal, iconic memory, and associative memory scores than children in the dyslexia group. Implications for the remediation of dyslexia are discussed.

Auditory Perception↗
PubMed2002

Prevalence and clinical characteristics of dyslexia in primary school students.

BACKGROUND: Dyslexia is the most common subtype of learning disabilities with a prevalence ranging from 5-10 per cent. The central difficulty in dyslexia is the phonological awareness deficit. The authors have developed a screening test to assess the reading ability of Thai primary school students. OBJECTIVE: 1. To study the prevalence of dyslexia in first to sixth grade students at Wat Samiannaree School. 2. To study the clinical characteristics such as sex, neurological signs, verbal intelligence and comorbid attention deficit hyperactive disorder (ADHD) of the dyslexia group. METHOD: A total of 486 first to sixth grade students were administered "Raven's progressive matrices test" for estimation of intellectual functioning. Those who scored below the fifth percentile were labeled as mental retardation and excluded from the study. The students' reading ability was evaluated by 3 steps; first by classroom teachers using some items of the screening test, second by the researchers examining some more items individually, and third by the special educator assessing more details in reading and phonology. The students who had a reading ability two-grade levels below their actual grades and impairment in phonology were diagnosed with dyslexia. RESULTS: The prevalence of dyslexia and probable dyslexia were found to be 6.3 per cent and 12.6 per cent, respectively. The male to female ratio of dyslexia was 3.4:1. The dyslexia group had significantly lower Thai language scores than those of the normal group (p < 0.05). All of the dyslexia group had a normal grossly neurological examination but 90 per cent showed positive soft neurological signs. Mean verbal intellectual quotient score in the dyslexia group assessed by using Wechsler Intelligence Scales for Children--Revised was 76 +/- 7. The comorbid ADHD was 8.7 per cent in the dyslexia group. CONCLUSION: Dyslexia was a common problem among primary school students in this study. Further studies in a larger population and different socioeconomic statuses are required to determine the prevalence of dyslexia in the general population. The authors suggest evaluating the reading ability carefully by using a test that can detect phonological awareness deficit in all children who have learning problems.

Child↗
PubMed2006

Directional motion contrast sensitivity in developmental dyslexia.

The present study compared the perception of visual motion in two dyslexia classification schemes; the [Boder, E. (1973). Developmental dyslexia: a diagnostic approach based on three atypical reading-spelling patterns. Developmental Medicine and Child Neurology, 15, 663-687.] dyseidetic, dysphonetic and mixed subgroups and [Williams, M. J., Stuart, G. W., Castles, A., & McAnally, K. I. (2003). Contrast sensitivity in subgroups of developmental dyslexia. Vision Research, 43, 467-477.] surface, phonological and mixed subgroups by measuring the contrast sensitivity for drifting gratings at three spatial frequencies (1.0, 4.0, and 8.0 c/deg) and five drift velocities (0.75, 3.0, 6.0, 12.0, and 18.0 cyc/s) in a sample of 32 children with dyslexia and 32 matched normal readers. The findings show that there were no differences in motion direction perception between normal readers and the group with dyslexia when dyslexia was taken as a homogeneous group. Motion direction perception was found to be intact in the dyseidetic and surface dyslexia subgroups and significantly lowered in both mixed dyslexia subgroups. The one inconsistency in the findings was that motion direction perception was significantly lowered in the [Boder, E. (1973). Developmental dyslexia: a diagnostic approach based on three atypical reading-spelling patterns. Developmental Medicine and Child Neurology, 15, 663-687.] dysphonetic subgroup and intact in the [Williams, M. J., Stuart, G. W., Castles, A., & McAnally, K. I. (2003). Contrast sensitivity in subgroups of developmental dyslexia. Vision Research, 43, 467-477.] phonological subgroup. The findings also provide evidence for the presence of a disorder in sequential and temporal order processing that appears to reflect a difficulty in retaining sequences of non-meaningful auditory and visual stimuli in short-term working memory in children with dyslexia.

Adolescent↗
PubMed2004

The prevalence of dyslexia and AD/HD in a sample of forensic psychiatric rapists.

The prevalence of dyslexia and attention deficit/hyperactivity disorder (AD/HD) (DSM-IV) is markedly increased among those who are sentenced for criminal offences. The aim of the study was to identify developmental disabilities, dyslexia and AD/HD among severely disturbed men in forensic psychiatric care, and to study the co-occurrence of such disabilities, with the objective to discuss the importance of the diagnoses in forensic psychiatry. The participants were 10 males who had committed rape on adult women, and included two murder-rapists, one of which had murdered more than one victim (i.e. a serial murderer). All had been assigned to special long-term forensic psychiatric care, based predominantly on a psychodynamic ground. In order to be identified as having dyslexia, a participant's performance on at least three out of four tests of academic skills had to be markedly below the expected level (more than two stanine steps), given the participant's non-verbal intellectual capacity and considering the length of his education. AD/HD was investigated by studying the participants' forensic psychiatric files and by a clinical interview. Seven of the 10 participants met the DSM-IV criteria for dyslexia, and six of them met the DSM-IV criteria for AD/HD. Four participants had AD/HD and dyslexia, three had AD/HD but no dyslexia, and two had dyslexia but no AD/HD. Only one participant had neither dyslexia nor AD/HD. The participants with dyslexia performed well in tests assessing non-verbal reasoning, visuo-spatial capacity and visual memory. Although the generalization of the results from 10 rapists is severely limited, the results indicate the importance of assessing dyslexia as well as AD/HD in people who are admitted for forensic psychiatric assessment. The lack of correct diagnoses may negatively influence the choice of appropriate forensic psychiatric care. Early assessment of those disorders might have a positive influence on the psychological development and socialization process in people with dyslexia and/or AD/HD.

Adolescent↗