Mirko Uljarević, Napoleon Katsos, Kristelle Hudry and Jenny L. Gibson
Language and communication skills are essential aspects of child development, which are often disrupted in children with neurodevelopmental disorders. Child psychiatrists, psychologists and others working in allied disciplines generally have pre- or post-registration training in assessment of linguistic development; however, practitioners may be less familiar with what to expect from a multilingual child, especially when a neurodevelopmental disorder is present or suspected.
Multilingualism has potential to influence approaches to assessment of parent–child relationships, developmental assessment, diagnostic formulation, intervention and educational support. Multilingual parents of children with neurodevelopmental disorders report concerns over whether or not to raise their children to be multilingual. Investigation of potential benefits and challenges of multilingualism for children with neurodevelopmental disorders is therefore not only a significant research area, but also one which has important clinical implications.
Clinical decision-making should in principle be informed by the latest evidence; however, this is not an easy task for practitioners, given the sheer volume of published research. Moreover, existing research on multilingualism and neurodevelopmental disorders varies widely in terms of its aims, focus and methodology, and much of the relevant research lies in journals which are not typically accessed by those working in frontline services. Therefore, in our practitioner review, we intend to provide an accessible, systematic review and integration of current findings on multilingualism and neurodevelopmental disorders. Our aim is to provide a snapshot of the current state-of-the-art in research that would help inform the practice of relevant professions.
We begin with an overview of international research on the language development of multilingual, typically developing children. We also alert practitioners to the debate surrounding recently emerging findings which suggest multilingualism may be associated with improved performance on of measures of executive function and social cognition. These topics are then discussed with reference to clinical practice and The World Health Organization International Classification of Functioning, Disability and Health (ICF, WHO, 2007), before moving on to a systematic review of multilingualism in neurodevelopmental disorders.
Our review identified 51 studies and showed that the literature to-date has mostly focused on Communication Disorders (38) and Autism Spectrum Disorder (ASD) (10), with just two studies investigating multilingualism and Intellectual Disability. Many studies had problematic designs as they compared multilingual individuals with neurodevelopmental disorders to multi- or monolingual typically developing individuals, making it difficult to isolate effects of multilingualism per se.
Nevertheless, studies which found a disadvantage for multilingual children with neurodevelopmental disorders were rare. In fact, when restricting our attention to those studies which compared a multilingual group with developmental disorders to a monolingual group with similar disorders, the findings consistently show no adverse association with language development or other aspects of functioning. Encouragingly, in the case of ASD a positive effect on communication and social functioning has been observed. Qualitative research identified from this review also underscores the value of multilingualism for participation in religious, family and community life. We also invite practitioners to consider the potential value of encouraging parent–child interaction in the parent's mother tongue as a way to maximize potential for parent–child synchrony, sensitive responding and fostering warmth. However, this latter point is yet to be empirically established.
We conclude with discussion of implications for clinical practice and for future research. The evidence indicates that assumptions about the potential difficulties (and benefits) of multilingualism for individuals with developmental disorders should be challenged within communities of professional practice. We encourage practitioners to consider multilingualism within the broader framework of a social model of disability and with reference to children's rights under the United Nations Convention on the Rights of the Child. Finally, we identify gaps in the literature as well as methodological issues which will require attention in future research.
In summary, we believe this review will be a useful and thought-provoking resource for an evidence-informed approach to working and researching with multilingual families with children with neurodevelopmental disorders.