Original paper: Comorbidities in preschool children at family risk of dyslexia
While a number of models have been proposed that implicate the inter-relationship between motor, cognitive and language domains on children’s developmental outcomes (e.g. Pennington, 2004), research evidence on the interplay of these skills early in development has been limited. Difficulties in one or more of these developmental domains may reflect the early symptoms of one or more developmental conditions. Their interplay is of particular interest because developmental disorders rarely occur in isolation from each other. Most children with Development Coordination Disorder (DCD), Attention Deficit Hyperactivity Disorder (ADHD), Autism Spectrum Disorder (ASD) and language impairment show symptoms of other conditions either at a clinical or sub-clinical level. Children with DCD for example frequently show difficulties in visuo-spatial working memory and with tasks that require cognitive planning in a similar pattern to that displayed by many children with ADHD. Similarly children with ADHD frequently show impaired fine and gross motor skills in comparison to their peers. The importance of this study, conducted by researchers Debbie Gooch, Charles Hulme, Hannah Nash and Margaret Snowling, lies in being one of the first to examine the interplay of motor, language and cognitive skills from an early stage of development. It contributes significantly to understanding the impact of co-occurring symptoms for developmental outcomes of children with developmental disorders. Before I outline what I think are the most pertinent contributions this paper makes to the literature, let us explore what the study involved.
Gooch and colleagues examined the co-occurrences between motor skills, executive function and language skills in children at family risk of dyslexia. A longitudinal design enabled reporting of data across two developmental time points when the children were around 3½ and 4½ years. The sample involved a 2 x 2 design focused on family risk of dyslexia and the presence of language impairment and thus comprised groups of children with; family risk only, language impairment only, family risk and language impairment and typically developing children. The researchers reported that difficulties in executive function, attention and motor skills were associated with language impairment rather than risk status associated with familial dyslexia. Critically these findings were reported across objective measures and parent reports, and observed at both time points, suggesting these impairments are stable across this period.
The first, and most basic, implication of this study relates to this finding of a relationship between these domains and language impairment. As the researchers conclude “comorbidity between developmental disorders can be observed in the preschool years”. This finding has contributed to growing evidence that supports associations between cognitive, motor and language domains that impact developmental outcomes, here reported early in development.
The second implication of this study concerns follow-on findings drawn from the use of an ongoing longitudinal research programme with the children included in the current sample. Gooch et al. (2014) ask a series of questions that follow from their findings that are subsequently answered in further published work by the research team. For example, what role does executive functions play in children’s development outcomes? Gooch et al. (2016) report a strong stability in both children’s language skills and executive function from preschool into the early school years. Their findings suggest that children’s executive function skills, but not their language skills, predict attention and behaviour with development. Another paper by the group (Thompson et al., 2015) suggests that good executive function provides some compensation for the impact of low ‘readiness’ for learning to read. Similarly, motor skills were observed to be associated with literacy development at one time point (age 6) which the authors reasonably argue may reflect the positive impact of having a good pencil grip at that age.
While the researcher’s central focus was to examine the relationship between language and reading, I would argue that an important implication of the Gooch et al. (2014) study is the finding that early motor skills are related to the development of good reading skills. The authors reported that pre-school motor skills indeed predicted unique variance in reading skills. The mechanisms of this relationship are not explored within the Gooch et al. (2014) study and it cannot be inferred as to whether this reflects a causal relationship or arises from some other factor that impacts both motor skills and literacy. Nonetheless, the finding is important in light of a recent study that links impaired motor skills observed early in development with academic outcomes much later in development in adolescence.
Harrowell et al. (2018) reported poor academic outcomes in adolescents aged 16 years who as children scored lower than 5th percentile on movement assessments. These 16 year olds achieved a median of 2 GCSE’s in comparison to a median of 7 by their peers, even after adjustment for gender, socio-economic status and IQ. The significance of this finding is emphasised by the methodological design adopted. This prospective cohort design linked data from the Avon Longitudinal Study of Parents and Children (ALSPAC) to data from national exam results (General Certificate of Secondary Education), comparing 254 adolescents who met the criteria for DCD with 5425 controls. These findings of poor academic outcomes in adolescents who showed poor motor skills in early childhood suggests that the link between early motor skills and literacy reported by Gooch et al. (2014) in the pre-school years is sustained across development and may extend to a broad range of academic subjects.
Early observation of the link between motor development and literacy within the Gooch et al. (2014) study highlights the potential role for early intervention in children with impaired motor skills to ease the development of later academic difficulties. This is likely to involve a range of intervention types. The poor academic outcomes for children with early motor control difficulties is astounding considering the severity and breadth at which they are reported and the fact they cannot be accounted for by gender, IQ and socio-economic status. These findings collectively emphasise the need for further research to help understand the range of strengths and weaknesses in children with motor difficulties and the mechanisms which underpin the relationship between early motor skills and academic learning. We also need to identify appropriate early interventions to facilitate successful academic learning in this significantly large proportion, what is in fact 5%, of our population.
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