Dyslexia

Dyslexia is a learning difficulty that primarily affects the skills involved in accurate and fluent word reading and spelling. 

There are several approaches to definitions that should be noted. These include: 

1. Symptoms-based definitions, e.g. Health Council of the Netherlands, British Psychological Society 
2. A problem that leads to literacy difficulties, e.g. British Dyslexia Association, National Institute of Child Health and Human Development 
3. The 10th revision of the International Classification of Diseases (ICD-10) (World Health Organisation, 2004).

If a child displays several of these indicators at pre-school, they may be dyslexic:

• confusion between directional words, for example, up/down, in/out
• difficulty with sequence, for example bead sequences, later with days of the week or numbers
• persistent jumbled phrases, for example ‘cobbler's club’ for ‘toddler's club’
• difficulty learning nursery rhymes and rhyming words.

Pre-school, non-language indicators include:

• difficulties getting dressed and putting shoes on the correct feet
• enjoys being read to but shows no interest in letters or words
• often accused of not listening or paying attention
• difficulty with catching, kicking, or throwing a ball; and with hopping or skipping
• difficulty with clapping a simple rhythm.

There are many conflicting theories of dyslexia, such as cerebellar (Nicolson et al, 2001) and magnocellular hypotheses (Stein, 2001). Both refer to structural differences. Research has been attempting to identify the underlying cause of those structural differences through brain scans and genetic research.

Reduced processing capability and neural integration of letters and speech sounds have been identified using functional magnetic resonance imaging as a probable significant underlying cause of dyslexia in many cases, explaining up to 40% of the variance in reading performance (Blau et al. 2010). Areas implicated include the anterior superior temporal gyrus, planum temporale or Heschl sulcus, superior temporal sulcus and fusiform gyrus.

Genetic

The research into the genetic origins of dyslexia is, at best, of variable quality because of the nature of identification of the cohorts. Since dyslexia (and reading) involves multiple cognitive processes, it is clear that there cannot be one underlying difficulty, but instead

A child’s behaviour may be an early indicator of learning differences. It can range from shyness and a lack of self esteem to over-confidence. 

In addition, a preschool child who is potentially dyslexic may: 

• know colours but confuse them – for example saying ‘black’ instead of ‘brown’ 
• have an early lisp 
• struggle to remember the label for known objects – for example table, chair 
• confuse directional words like up/down, in/out 
• find it hard to learn nursery rhymes or even rhyming words 
• have a problem with sequences – for example coloured beads – and later with days of the week or numbers.

Further support, information and advice is available from: 

The British Dyslexia Association 

www.bda-dyslexia.org.uk

References

Blau V, Reithler J, van Atteveldt N et al. Deviant processing of letters and speech sounds as proximate cause of reading failure: a functional magnetic resonance imaging study of dyslexic children. Brain. 2010;133(Pt 3):868-79. https://doi.org/10.1093/brain/awp308

Nicolson RI, Fawcett AJ, Dean P. developmental dyslexia: the cerebellar deficit hypothesis. Trend Neurosci. 2001; 24(9):508-11. https://doi.org/10.1016/s0166-2236(00)01896-8

Stein J. The magnocellular theory of developmental dyslexia. Dyslexia. 2001;7(1):12-36. https://doi.org/10.1002/dys.186

World Health Organisation. ICD_10 Version:2019. 2019. https://icd.who.int/browse10/2019/en#/ (accessed 6 December 2022)