Practitioner Review: Multilingualism and neurodevelopmental disorders – an overview of recent research and discussion of clinical implications

Language and communication skills are essential aspects of child development, which are often disrupted in children with neurodevelopmental disorders. Cutting edge research in psycholinguistics suggests that multilingualism has potential to influence social, linguistic and cognitive development. Thus, multilingualism has implications for clinical assessment, diagnostic formulation, intervention and support offered to families. We present a systematic review and synthesis of the effects of multilingualism for children with neurodevelopmental disorders and discuss clinical implications. Methods We conducted systematic searches for studies on multilingualism in neurodevelopmental disorders. Keywords for neurodevelopmental disorders were based on Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition categories as follows; Intellectual Disabilities, Communication Disorders, Autism Spectrum Disorder (ASD), Attention‐Deficit/Hyperactivity Disorder, Specific Learning Disorder, Motor Disorders, Other Neurodevelopmental Disorders. We included only studies based on empirical research and published in peer‐reviewed journals. Results Fifty studies met inclusion criteria. Thirty‐nine studies explored multilingualism in Communication Disorders, 10 in ASD and two in Intellectual Disability. No studies on multilingualism in Specific Learning Disorder or Motor Disorders were identified. Studies which found a disadvantage for multilingual children with neurodevelopmental disorders were rare, and there appears little reason to assume that multilingualism has negative effects on various aspects of functioning across a range of conditions. In fact, when considering only those studies which have compared a multilingual group with developmental disorders to a monolingual group with similar disorders, the findings consistently show no adverse effects on language development or other aspects of functioning. In the case of ASD, a positive effect on communication and social functioning has been observed. Conclusions There is little evidence to support the widely held view that multilingual exposure is detrimental to the linguistic or social development of individuals with neurodevelopmental disorders. However, we also note that the available pool of studies is small and the number of methodologically high quality studies is relatively low. We discuss implications of multilingualism for clinical management of neurodevelopmental disorders, and discuss possible directions for future research.UK Arts & Humanities Research Council. Grant Number: AH/N004671/

Brain dynamics of meal size selection in humans.

Although neuroimaging research has evidenced specific responses to visual food stimuli based on their nutritional quality (e.g., energy density, fat content), brain processes underlying portion size selection remain largely unexplored. We identified spatio-temporal brain dynamics in response to meal images varying in portion size during a task of ideal portion selection for prospective lunch intake and expected satiety. Brain responses to meal portions judged by the participants as 'too small', 'ideal' and 'too big' were measured by means of electro-encephalographic (EEG) recordings in 21 normal-weight women. During an early stage of meal viewing (105-145ms), data showed an incremental increase of the head-surface global electric field strength (quantified via global field power; GFP) as portion judgments ranged from 'too small' to 'too big'. Estimations of neural source activity revealed that brain regions underlying this effect were located in the insula, middle frontal gyrus and middle temporal gyrus, and are similar to those reported in previous studies investigating responses to changes in food nutritional content. In contrast, during a later stage (230-270ms), GFP was maximal for the 'ideal' relative to the 'non-ideal' portion sizes. Greater neural source activity to 'ideal' vs. 'non-ideal' portion sizes was observed in the inferior parietal lobule, superior temporal gyrus and mid-posterior cingulate gyrus. Collectively, our results provide evidence that several brain regions involved in attention and adaptive behavior track 'ideal' meal portion sizes as early as 230ms during visual encounter. That is, responses do not show an increase paralleling the amount of food viewed (and, in extension, the amount of reward), but are shaped by regulatory mechanisms

Sub-threshold autism traits: The role of trait emotional intelligence and cognitive flexibility.

Theory and research suggests that features of autism are not restricted to individuals diagnosed with autism spectrum disorders (ASDs), and that autism-like traits vary throughout the general population at lower severities. The present research first investigated the relationship of autism traits with trait emotional intelligence and empathy in a sample of 163 adults aged between 18 and 51 years (44% male). It then examined performance on a set of tasks assessing social cognition and cognitive flexibility in 69 participants with either high or low scores on ASD traits. Results confirm that there is pronounced variation within the general population relating to ASD traits, which reflect similar (though less severe) social-cognitive and emotional features to those observed in ASDs

Ret receptor tyrosine kinase sustains proliferation and tissue maturation in intestinal epithelia.

Expression of the Ret receptor tyrosine kinase is a defining feature of enteric neurons. Its importance is underscored by the effects of its mutation in Hirschsprung disease, leading to absence of gut innervation and severe gastrointestinal symptoms. We report a new and physiologically significant site of Ret expression in the intestine: the intestinal epithelium. Experiments in Drosophila indicate that Ret is expressed both by enteric neurons and adult intestinal epithelial progenitors, which require Ret to sustain their proliferation. Mechanistically, Ret is engaged in a positive feedback loop with Wnt/Wingless signalling, modulated by Src and Fak kinases. We find that Ret is also expressed by the developing intestinal epithelium of mice, where its expression is maintained into the adult stage in a subset of enteroendocrine/enterochromaffin cells. Mouse organoid experiments point to an intrinsic role for Ret in promoting epithelial maturation and regulating Wnt signalling. Our findings reveal evolutionary conservation of the positive Ret/Wnt signalling feedback in both developmental and homoeostatic contexts. They also suggest an epithelial contribution to Ret loss-of-function disorders such as Hirschsprung disease

Resistance to autosomal dominant Alzheimer's disease in an APOE3 Christchurch homozygote: a case report.

We identified a PSEN1 (presenilin 1) mutation carrier from the world's largest autosomal dominant Alzheimer's disease kindred, who did not develop mild cognitive impairment until her seventies, three decades after the expected age of clinical onset. The individual had two copies of the APOE3 Christchurch (R136S) mutation, unusually high brain amyloid levels and limited tau and neurodegenerative measurements. Our findings have implications for the role of APOE in the pathogenesis, treatment and prevention of Alzheimer's disease