2.4 Language and literacy abilities of children with NF1
2.4.5 Summary and rationale for current studies
There is a large body of research describing the high frequency of academic difficulties experienced by children with NF1 with reading skills being the most commonly investigated. The estimated rates of dyslexia in children with NF1 range from 8.6% to 67% depending on the criteria used and highlight the need for a uniform approach to diagnosis. While it is evident that children with NF1 are at high risk of reading difficulties there are still a number of questions that remain.
While there is evidence to suggest that school-age children with NF1 display significant difficulties in literacy precursor skills such as phonological awareness (Chaix et al., 2017), no studies have investigated the phonological skills of young children with NF1. Further, only one study has included an objective measure of a significant preliteracy skill, letter-word identification in young children (40 months old) with NF1 (Lorenzo et al., 2013). Results of this study indicated that their performance on a letter/word identification task was significantly poorer than unaffected children. In combination, these studies provide preliminary evidence that preliteracy skills may be impaired in young children with NF1. There is evidence to suggest that the preschool period and first year of schooling is a significant period for the development of preliteracy abilities such as phonological skills and letter-sound knowledge (Blaiklock, 2004; Lonigan et al., 2009; Whitehurst & Lonigan, 1998). This suggests that five to six years may be a critical time period to assess children’s
is needed and ultimately would allow for early literacy intervention for those children who are potentially at a higher risk of later reading difficulties.
To date, there has been little investigation into the specific impairments that may underlie reading difficulties in school-age children with NF1. Models of reading, such as the DRM (Coltheart et al., 2001), describe the individual components that are needed for adequate word reading ability, thereby providing a systematic method of assessing reading subskills and identifying difficulties. For example, the DRM proposes that that in order to adequately decode words (using the sublexical reading route) children require the following subskills: the ability to correctly identify letters, to produce the appropriate sounds corresponding to these letters, and finally to blend these sounds together to produce the word (Coltheart et al., 2001). While Watt et al. (2008) used the DRM as a framework to identify dyslexia in children with NF1, the majority of whom were classified as having phonological dyslexia (i.e. sublexical impairment), they did not examine the underlying subskills and factors that may have contributed to this impairment. Further the relatively small sample size and lack of a control group in this study limits the generalisability of the results. To improve our understanding of the reading difficulties frequently experienced by children with NF1, it is essential to further investigate the specific types of reading impairment (i.e. sublexical, lexical) in children with NF1 and associated weaknesses in underlying subskills.
In addition, the relationship between reading difficulties and other cognitive impairments in children with NF1 is not well defined. Findings from one study (Cutting & Levine, 2010) suggest a possible link between visuospatial weaknesses and reading deficits. Further Cutting and Levine (2010) reported that ADHD
symptomatology was not significantly related to reading outcomes. In contrast another study identified higher rates of ADHD in children with reading impairments (Hyman et al., 2006). Additional investigation into the relationship between
weaknesses in visuospatial functioning, attention and reading is needed. Moreover, little is known about the impact of executive abilities such as working memory on reading in NF1. In the general population, children with poorer working memory are at higher risk of reading difficulties (Wang & Gathercole, 2013). Considering the high incidence of working memory deficits reported in NF1 (Payne et al., 2012) the
relationship between working memory and reading abilities in NF1 warrants further investigation.
Finally, despite the high incidence of reading and reading-related difficulties reported in children with NF1, there has only been one study examining the effects of a reading intervention. In the general population, the potential lifelong negative implications of dyslexia are widespread including increased risk of emotional and behavioural
problems, as well as poorer academic and occupational outcomes (Arnold et al., 2005; Castles et al., 2018; Daniel et al., 2006; 2015). This indicates the significant need for further investigation into effective treatment options for reading difficulties in NF1. Also additional research is needed assessing treatment effects (immediate and long- term), not only on those abilities specifically being targeted by the reading
intervention (i.e. word reading), but also on those more distal such as reading fluency, spelling and comprehension.
In addition, further examination of the cognitive factors that may impact on the efficacy of reading interventions would be beneficial. The only reading treatment study conducted to date found that a small group of children with NF1 and reading
difficulties responded better to a reading intervention with fewer visuospatial
demands as opposed to an intervention with more kinaesthetic demands (Barquero et al., 2015). The authors concluded that reading interventions that rely less on
visuospatial skills are better suited to children with NF1 (Barquero et al., 2015). However, it should be noted that the relationship between children’s response to treatment and their visuospatial functioning was not specifically examined.
Furthermore in this study, contrary to a previous finding (Cutting & Levine, 2010), children with NF1 and reading difficulties did not display distinct visuospatial deficits compared to an idiopathic group of children with reading difficulties (Barquero et al., 2015). Further exploration of the impact of visuospatial weaknesses and other
cognitive deficits (i.e. working memory, language) on treatment outcomes is needed.
In the following sections of this thesis are two published papers and a manuscript which aim to address these gaps in our knowledge by providing a detailed description of the literacy abilities of children with NF1, from preschool through to later school years, and to trial a treatment for children with reading difficulties. The first published paper is a cross-sectional study which aims to describe the preliteracy abilities of young children (aged 5-6 years) with NF1 compared to an unaffected control group. The second paper is a manuscript describing a cross-sectional study investigating the reading abilities and related cognitive skills of school-age children (7-12 years) compared to unaffected controls. In addition, children from this study identified as having reading difficulties were invited to participate in the intervention described in the third paper. The third published paper describes a reading intervention for school- age children with NF1 (7-12 years) and reading difficulties. Collectively, these studies
aim to contribute to a better understanding of the reading profile of children with NF1, and to establish the efficacy of reading intervention in this population.