Pursuit eye movements in dyslexic children: evidence for an immaturity of brain oculomotor structures?

Background: Dyslexia is a disorder found in 5–10% of school-aged children. Several studies reported visual deficits and oculomotor abnormalities in dyslexic children. The objective of our study was to examine horizontal pursuit performance in dyslexic children, despite its poor involvement in reading. Methods: Eye movements were recorded by video-oculography in 92 children (46 dyslexic children, mean age: 9.77 ± 0.26 and 46 non dyslexic, IQ- and age-matched children). Both the number of catch-up saccades occurring during pursuit task and the gain of pursuit were measured. Results: Catch-up saccades were significantly more frequent in the dyslexic group than in the non-dyslexic group of children. Pursuit performance (in terms of the number of catch-up saccades and gain) significantly improved with increasing age in the non-dyslexic children group only. Conclusions: The atypical pursuit patterns observed in dyslexic children suggest a deficiency in the visual attentional processing and an immaturity of brain structures responsible for pursuit triggering. This finding needs to be validated by neuroimaging studies on dyslexia population

Morning Plasma Melatonin Differences in Autism: Beyond the Impact of Pineal Gland Volume

While low plasma melatonin, a neuro-hormone synthesized in the pineal gland, has been frequently associated with autism, our understanding of the mechanisms behind it have remained unclear. In this exploratory study, we hypothesized that low melatonin levels in ASD could be linked to a decrease of the pineal gland volume (PGV). PGV estimates with magnetic resonance imaging (MRI) with a voxel-based volumetric measurement method and early morning plasma melatonin levels were evaluated for 215 participants, including 78 individuals with ASD, 90 unaffected relatives, and 47 controls. We first found that both early morning melatonin level and PGV were lower in patients compared to controls. We secondly built a linear model and observed that plasma melatonin was correlated to the group of the participant, but also to the PGV. To further understand the relationship between PGV and melatonin, we generated a normative model of the PGV relationship with melatonin level based on control participant data. We found an effect of PGV on normalized melatonin levels in ASD. Melatonin deficit appeared however more related to the group of the subject. Thus, melatonin variations in ASD could be mainly driven by melatonin pathway dysregulation

Meta-analysis of SHANK Mutations in Autism Spectrum Disorders: A Gradient of Severity in Cognitive Impairments.

International audienceSHANK genes code for scaffold proteins located at the post-synaptic density of glutamatergic synapses. In neurons, SHANK2 and SHANK3 have a positive effect on the induction and maturation of dendritic spines, whereas SHANK1 induces the enlargement of spine heads. Mutations in SHANK genes have been associated with autism spectrum disorders (ASD), but their prevalence and clinical relevance remain to be determined. Here, we performed a new screen and a meta-analysis of SHANK copy-number and coding-sequence variants in ASD. Copy-number variants were analyzed in 5,657 patients and 19,163 controls, coding-sequence variants were ascertained in 760 to 2,147 patients and 492 to 1,090 controls (depending on the gene), and, individuals carrying de novo or truncating SHANK mutations underwent an extensive clinical investigation. Copy-number variants and truncating mutations in SHANK genes were present in ∼1% of patients with ASD: mutations in SHANK1 were rare (0.04%) and present in males with normal IQ and autism; mutations in SHANK2 were present in 0.17% of patients with ASD and mild intellectual disability; mutations in SHANK3 were present in 0.69% of patients with ASD and up to 2.12% of the cases with moderate to profound intellectual disability. In summary, mutations of the SHANK genes were detected in the whole spectrum of autism with a gradient of severity in cognitive impairment. Given the rare frequency of SHANK1 and SHANK2 deleterious mutations, the clinical relevance of these genes remains to be ascertained. In contrast, the frequency and the penetrance of SHANK3 mutations in individuals with ASD and intellectual disability-more than 1 in 50-warrant its consideration for mutation screening in clinical practice

Child's cognitive development during the preschool period : an epidemiological approach

Ce travail de Thèse a consisté à étudier le développement cognitif pendant la période préscolaire à partir d'une cohorte longitudinale menée en France en population générale : la cohorte EDEN (N = 2002). Dans le cadre de l'épidémiologie cognitive, nous avons tenté de répondre à diverses questions de recherche dont le dénominateur commun est l'étude de la variabilité interindividuelle dans le développement cognitif. Tout d'abord, nous avons étudié les facteurs pré, péri et post-natals associés aux changements des performances linguistiques entre 2 et 3 ans. Puis, nous avons tenté d'identifier les facteurs environnementaux ayant un effet différentiel sur le développement verbal et non-verbal à 5-6 ans. Ensuite, nous avons exploré l'effet des performances linguistiques à 3 ans sur les symptômes de TDAH à 5-6 ans. Puis, nous avons cherché à déterminer si les enfants avec un haut niveau intellectuel présentaient davantage de difficultés émotionnelles, comportementales et relationnelles pendant la période préscolaire. Enfin, nous avons examiné l'intérêt des repères développementaux au cours des deux premières années de vie pour prédire le QI à 5-6 ans. Les résultats de ces études fournissent des données intéressantes pour les cliniciens ainsi que pour les décideurs de santé publique et contribuent à améliorer la compréhension du développement cognitif normal et pathologique.In this Thesis, we studied the cognitive development of children during the preschool period in a French longitudinal cohort: the EDEN prospective mother-child cohort (N = 2002). In the framework of cognitive epidemiology, we attempted to answer a variety of issues whose common denominator is the study of the sources of inter-individual variability. First, we identified the factors that predict change in language skills in a large sample of children between 2 and 3 years of age. Secondly, we determined whether early predictors of cognitive development affect some cognitive functions more than others. Thirdly, we examined the relationships between children’s language skills and symptoms of hyperactivity/inattention between 3 and 5.5 years. Fourthly, we determined whether high intelligence is associated with emotional, behavioral and social difficulties during the preschool period. Finally, we determined whether the developmental milestones at 4, 8, 12 and months predict children’s IQ at 5.5 years

Épidémiologie du développement cognitif de l'enfant pendant la période préscolaire

In this Thesis, we studied the cognitive development of children during the preschool period in a French longitudinal cohort: the EDEN prospective mother-child cohort (N = 2002). In the framework of cognitive epidemiology, we attempted to answer a variety of issues whose common denominator is the study of the sources of inter-individual variability. First, we identified the factors that predict change in language skills in a large sample of children between 2 and 3 years of age. Secondly, we determined whether early predictors of cognitive development affect some cognitive functions more than others. Thirdly, we examined the relationships between children’s language skills and symptoms of hyperactivity/inattention between 3 and 5.5 years. Fourthly, we determined whether high intelligence is associated with emotional, behavioral and social difficulties during the preschool period. Finally, we determined whether the developmental milestones at 4, 8, 12 and months predict children’s IQ at 5.5 years.Ce travail de Thèse a consisté à étudier le développement cognitif pendant la période préscolaire à partir d'une cohorte longitudinale menée en France en population générale : la cohorte EDEN (N = 2002). Dans le cadre de l'épidémiologie cognitive, nous avons tenté de répondre à diverses questions de recherche dont le dénominateur commun est l'étude de la variabilité interindividuelle dans le développement cognitif. Tout d'abord, nous avons étudié les facteurs pré, péri et post-natals associés aux changements des performances linguistiques entre 2 et 3 ans. Puis, nous avons tenté d'identifier les facteurs environnementaux ayant un effet différentiel sur le développement verbal et non-verbal à 5-6 ans. Ensuite, nous avons exploré l'effet des performances linguistiques à 3 ans sur les symptômes de TDAH à 5-6 ans. Puis, nous avons cherché à déterminer si les enfants avec un haut niveau intellectuel présentaient davantage de difficultés émotionnelles, comportementales et relationnelles pendant la période préscolaire. Enfin, nous avons examiné l'intérêt des repères développementaux au cours des deux premières années de vie pour prédire le QI à 5-6 ans. Les résultats de ces études fournissent des données intéressantes pour les cliniciens ainsi que pour les décideurs de santé publique et contribuent à améliorer la compréhension du développement cognitif normal et pathologique

Réflexions diagnostiques et thérapeutiques sur une série de cas d'enfants et d'adolescents présentant des troubles du comportement associés à un retard mental et confiés à l'Aide Sociale de l'Enfance

LE KREMLIN-B.- PARIS 11-BU Méd (940432101) / SudocSudocFranceF

Effect of siblings on numeracy and literacy skills, and the mediating role of parental interactions in the DEPP cohort

Previous studies show a correlation between sibship structure (for example, number of siblings) and language development of children, with the number of older siblings frequently being negatively associated with language development (Peyre et al. 2016, Havron et al. 2019). Sibship structure has also been more generally related with academic achievement and adult earnings (Black et al., 2005), even when socioeconomic status and other early predictors of cognitive development are adjusted. Recently, we have shown that this effect is mediated in part by parental investment: parents with more children tend to have lower parental investment in the target child, which is correlated with a lower language development of the child (Gurgand et al in prep). This is in line with Blake’s resource-dilution model (Blake, 1981), which states that a family has limited resources to distribute amongst their children. Thus, the more children there are, the fewer resources available per child – the presently relevant resources being time spent and activities with the child. These results are also consistent with the confluence model (Zajonk & Markus, 1975), which states that a child’s intellectual environment is made up of the average intellectual ability in the family, and as children have lower intellectual abilities than adults, having more children in the family brings the average down. Other sibship characteristics have been shown to be related to language, although not always with a clear relation. For example, the age difference between siblings has sometimes been positively associated with better educational achievement for older and younger siblings (Powell & Steelman 1990, 1993 for older and younger siblings, Buckles & Munnich 2012 for older siblings and Karwath et al. 2014 for younger siblings). Finally, the effect of sibling sex is still not completely clear, as some studies find a negative relation between having a brother and language development, compared to having a sister or no siblings (Jakiela et al., 2020, Havron et al., 2019), while other studies do not find this relation to be significant (Havron et al., submitted, Gurgand et al., in prep). In this study, we plan to examine these sibship characteristics’ associations with other domains than language development, namely literacy and numeracy. Using school data collected in first and fifth grade, we are interested in whether there is an effect of siblings (sex, number of older and younger siblings) on literacy skills, and whether this effect can also be found for numeracy skills. We hypothesize that the potential effect of siblings may be larger on literacy than on numeracy (as oral language better predicts literacy than numeracy). We also ask whether the association is mediated by parental investment. Finally, we wonder whether the language spoken by the parents moderates these possible relations