Search Results (6)

Background/Objectives: The Seeds of Literacy project has followed infants at family risk for dyslexia (FR group) and infants not at family risk (NFR group) since the age of 5 months, exploring whether infant measures of auditory sensitivity and phonological skills are related to later reading achievement. Here, we retrospectively assessed relations between infant performance on a rise time discrimination task with new pre-reading behavioural measures administered at 60 months. In addition, we re-classified dyslexia risk at 60 months and again assessed relations to rise time sensitivity. Participants were re-grouped using the pre-reading behavioural measures as either dyslexia risk at 60 months (60mDR) or no dyslexia risk (60mNDR). Methods: FR and NFR children (44 English-learning children) completed assessments of rise time discrimination at 10 and/or 60 months, phonological awareness, phonological memory, rapid automatised naming (RAN), letter knowledge, and language skills (receptive vocabulary and grammatical awareness). Results: Longitudinal analyses showed significant time-lagged correlations between rise time sensitivity at 10 months and both RAN and letter knowledge at 60 months. Rise time sensitivity at 60 months was significantly poorer in those children re-grouped as 60mDR, and rise time sensitivity was significantly related to concurrent phonological awareness, RAN, letter knowledge, and receptive vocabulary, but not to tests of grammatical awareness. Conclusions: The data support the view that children’s rise time sensitivity is significantly related to their pre-reading phonological abilities. These findings are discussed in terms of Temporal Sampling theory. Full article

Children with dyslexia are at elevated risk of internalising and externalising mental health concerns. Our aim was to scope the extent and nature of the literature investigating factors which may influence this association. We systematically searched the peer-reviewed and grey literature with no restrictions on the date. We included both qualitative and quantitative studies. Inclusion criteria included: (1) a focus on childhood (≤18 years) reading/learning difficulties; (2) internalising and/or externalising symptoms; and (3) a potentially modifiable third factor (e.g., self-esteem). Ninety-eight studies met the inclusion criteria. We organised the studies according to individual, family, and community-level third factors. Whilst a range of third factors were identified, relatively few researchers tested associations between the third factor and mental health in the context of dyslexia. Furthermore, there was a focus on primary rather than secondary school experience and a reliance, in many cases, on teacher/parent perspectives on children’s mental health. Future researchers are encouraged to explore links between socio-emotional skills, coping strategies, school connectedness, and mental health in the context of dyslexia. Research of this nature is important to assist with the identification of children who are more (or less) at risk of mental health concerns and to inform tailored mental health programs for children with dyslexia. Full article

The study of the multiple processes involved in learning how to read can contribute towards the early detection of good and bad readers. However, it is necessary to take into consideration different biopsychosocial risk factors (pre- and perigestational, neonatal, medical, developmental and family-related) that may have a significant impact on neurodevelopment, producing atypical cognitive development that could lead to the presence of reading difficulties. The objective of this study was to identify the main psycholinguistic abilities involved in the early reading performance and analyse their relationship to biopsychosocial risk factors. A total of 110 subjects between the ages of 4 and 7 years old and enrolled in state-run schools in Spain participated in the study. Significant correlations were found between different psycholinguistic abilities and certain biopsychosocial risk factors (having had hyperbilirubinemia, having obtained a score lower than 9 on the Apgar test, having had language problems or a sibling with dyslexia). This relationship should be taken into account in the study of learning difficulties as a potential indicator to predict later reading development and even the presence of developmental dyslexia. Full article

Although allophonic speech processing has been hypothesized to be a contributing factor in developmental dyslexia, experimental evidence is limited and inconsistent. The current study compared the categorization of native similar sounding vowels of typically developing (TD) children and children at familial risk (FR) of dyslexia. EEG response was collected in a non-attentive passive oddball paradigm from 35 TD and 35 FR Dutch 20-month-old infants who were matched on vocabulary. The children were presented with two nonwords “giep” [ɣip] and “gip” [ɣIp] that contrasted solely with respect to the vowel. In the multiple-speaker condition, both nonwords were produced by twelve different speakers while in the single-speaker condition, single tokens of each word were used as stimuli. For both conditions and for both groups, infant positive mismatch response (p-MMR) was elicited, and the p-MMR amplitude was comparable between the two groups, although the FR children had a later p-MMR peak than the TD children in the multiple-speaker condition. These findings indicate that FR children are able to categorize speech sounds, but that they may do so in a more effortful way than TDs. Full article

This paper reviews the observations of the Jyväskylä Longitudinal Study of Dyslexia (JLD). The JLD is a prospective family risk study in which the development of children with familial risk for dyslexia (N = 108) due to parental dyslexia and controls without dyslexia risk (N = 92) were followed from birth to adulthood. The JLD revealed that the likelihood of at-risk children performing poorly in reading and spelling tasks was fourfold compared to the controls. Auditory insensitivity of newborns observed during the first week of life using brain event-related potentials (ERPs) was shown to be the first precursor of dyslexia. ERPs measured at six months of age related to phoneme length identification differentiated the family risk group from the control group and predicted reading speed until the age of 14 years. Early oral language skills, phonological processing skills, rapid automatized naming, and letter knowledge differentiated the groups from ages 2.5–3.5 years onwards and predicted dyslexia and reading development, including reading comprehension, until adolescence. The home environment, a child’s interest in reading, and task avoidance were not different in the risk group but were found to be additional predictors of reading development. Based on the JLD findings, preventive and intervention methods utilizing the association learning approach have been developed. Full article

Developmental dyslexia is a frequently diagnosed reading disorder, found in 4–10% of the population, characterised by reading difficulty despite normal intelligence and educational opportunities. A large and methodologically diverse body of literature suggests that the origins of developmental dyslexia are biological, but the exact nature of the underlying mechanisms remains under debate. Several neurobehavioural studies support the view that an impairment in phonological processing, namely in segmenting and manipulating the language constituents, is the core deficit of dyslexia. Other studies focus on possible visual deficits in dyslexia, particularly on a subsystem of the visual pathways (magnocellular theory of dyslexia). Finally, it has been found that dyslexics present difficulties in processing brief stimuli in rapid temporal sequences.This“temporal processing impairment” theory of dyslexia encompasses several systems (visual, auditive, motor) and could account for the phonological deficits, the visual deficits as well as other symptoms often associated with dyslexia. The relative contribution of the deficits underlined by these three principal hypotheses in the aetiology of dyslexia remains unknown and needs further investigation. This paper reviews, in light of these cognitive hypotheses, the neurobiological results provided by selected structural and functional magnetic resonance imaging (MRI) studies. MRI offers a high spatial resolution and contrast, without the risk of radiation exposure. It has therefore become the preferred imaging technique for children and adolescents. The two goals of this review are (1) to demonstrate how MRI studies contribute to our understanding of the mechanisms underlying developmental dyslexia and (2) to update clinicians on the methodological issues pertaining to image acquisition and analysis, promoting critical reading of future MRI studies. Historically, neuropathological studies were the first to lay claim for a neurological basis of dyslexia. These postmortem analyses on a small number of dyslexic subjects revealed microscopic cortical anomalies as well as abnormal patterns of hemispheric asymmetry. Their results, even if controversial, suggested a possible abnormality in dyslexics’ prenatal brain development and inspired the subsequent in vivo imaging studies. Though initial studies pointed to a pathological rightward asymmetry or symmetry of the planum temporale (superior surface of the temporal lobe, related to language functions), recent findings suggest more subtle differences regarding the tissue composition of the temporal lobe as well as a more widespread variation in neuroanatomy. Several functional imaging studies provide converging evidence that a disruption in multiple cortical regions impairs the dyslexics during reading. Specifically, underactivation of a left posterior cortical region (temporo-parieto-occipital cortex) has been observed among different dyslexic populations during phonological tasks. Moreover, an overactivation of the homologous regions in the right hemisphere and the inferior frontal gyrus was attributed to a compensating strategy in the dyslexic group. It has been hypothesised that a deficit of connectivity between these cortical regions could be an additional neural basis for dyslexia.This hypothesis is supported by structural studies that found abnormalities in the corpus callosum and, using diffusion tensor magnetic resonance imaging, in the microstructure of the white matter. In the last years, functional MRI studies investigated the more controversial magnocellular and temporal processing deficit theories of dyslexia. The combination of various neuroimaging techniques will allow future studies to specify the biological markers underlying developmental dyslexia and to better relate them to the different subtypes of developmental dyslexia. An understanding of the neurological mechanisms of dyslexia will ultimately promote more targeted treatments and improve the life of affected individuals and their families.
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