Oral language deficits in familial dyslexia: A meta-analysis and review.

Margaret J Snowling,Monica Melby-Lervåg

doi:10.1037/bul0000037

Abstract

This article reviews 95 publications (based on 21 independent samples) that have examined children at family risk of reading disorders. We report that children at family risk of dyslexia experience delayed language development as infants and toddlers. In the preschool period, they have significant difficulties in phonological processes as well as with broader language skills and in acquiring the foundations of decoding skill (letter knowledge, phonological awareness and rapid automatized naming [RAN]). Findings are mixed with regard to auditory and visual perception: they do not appear subject to slow motor development, but lack of control for comorbidities confounds interpretation. Longitudinal studies of outcomes show that children at family risk who go on to fulfil criteria for dyslexia have more severe impairments in preschool language than those who are defined as normal readers, but the latter group do less well than controls. Similarly at school age, family risk of dyslexia is associated with significantly poor phonological awareness and literacy skills. Although there is no strong evidence that children at family risk are brought up in an environment that differs significantly from that of controls, their parents tend to have lower educational levels and read less frequently to themselves. Together, the findings suggest that a phonological processing deficit can be conceptualized as an endophenotype of dyslexia that increases the continuous risk of reading difficulties; in turn its impact may be moderated by protective factors.

Highlights

Oral Language Deficits in Familial Dyslexia: a Meta-analysis and Review Literacy skills are the key to educational attainments and these in turn promote access to career opportunities and employment
The methodology has distinct advantages over the more standard case-control approach; first it is free of clinical bias since children are recruited before they enter formal reading instruction; second, it allows us to disentangle possible causes of dyslexia from its consequences; third, and arguably most importantly, it is the only methodology that can allow the identification of risk factors in the preschool period, together with likely protective factors
Methodological Issues This review has identified a number of methodological issues that limit the conclusions that can be drawn from studies of children at family risk of dyslexia

Summary

Introduction

Oral Language Deficits in Familial Dyslexia: a Meta-analysis and Review Literacy skills are the key to educational attainments and these in turn promote access to career opportunities and employment. Consistent with this, the Diagnostic and Statistical Manual of the American Psychiatric Association (DSM-5; American Psychiatric Association, 2013) groups together reading disorders (dyslexia), mathematical disorders and disorders of written expression under a single overarching diagnosis of Specific Learning Disorder within the broader category of Neurodevelopmental Disorders It has been known for many years that dyslexia, like other neurodevelopmental disorders, runs in families and studies of large twin samples demonstrate that reading and the. The current review is organized around four of the main questions which family-risk studies have addressed: the prevalence of dyslexia in children with a first-degree-affected

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