Dyslexia

Original Editor - Maram Salem Top Contributors - Maram Salem

Introduction

Dyslexia is a prevalent learning disorder of neurobiological origin. It is characterised by a person's difficulty with reading, writing, and spelling. This is due to improper decoding with phonological processing (i.e., the use of sounds of one's language to process spoken and written language), which consequently affects one's ability to read, speak, spell, and learn a second language. People with dyslexia can also demonstrate poor spelling abilities. It is one the most common learning disabilities to affect children.

Definition

People with developmental dyslexia demonstrate difficulty with reading, word recognition, and spelling despite exhibiting age-appropriate intelligence and sensory abilities.Comprehension is usually intact. People with dyslexia will have trouble matching and combining letters on a page to sound out words (decoding). When this first step is disrupted, combining letter sounds and words to read sentences because complex. Fluency in reading becomes difficult. This struggle has no impact and is not reflective of the overall intelligence of the individual.

Children and adults with dyslexia have difficulty quickly and correctly hearing, storing, recalling, and making different speech sounds. They also have difficulty with spelling and rapid visual-verbal responding.This becomes more evident with failed attempts to blend letters to sound out words, incorrect spelling, and difficulty verbalising letters and words when prompted.

Dyslexia is a brain-based disorder. Parts of the brain responsible for detection and processing of auditory stimuli/sounds are affected. Children born with dyslexia are more likely to have family members with the impairment (compared to other children). It is important to note that dyslexia does not affect the brain's structure, its intellectual capabilities, creativity, or emotional wellbeing of a person.

Prevalence

The prevalence of dyslexia varies by country. In the United States, it is estimated that dyslexia affects 20% of the population and represents 80-90% of all those with learning disabilities. In the United Kingdom, 10% of the population is believed to be dyslexic. There is a relatively small male skewed dominance diagnosed with dyslexia than female (1.5-3:1).One possible reason for this slightly higher prevalence in boys is that boys are subject to screening for other comorbidities, such as ADHD.

Dyslexia occurs in people of all backgrounds at all ages and intellectual levels.

Co-morbidities

Co-morbidites, or the presence of 2 or more medical conditions, can occur with dyslexia. As previously mentioned, ADHD is a common co-morbidity, as well as language impairment and speech sound disorder. Language impairment is defined as difficulty with the development of structural language (e.g., grammar and vocabulary). Speech sound disorder is the ability to effectively and accurately produce the sounds of one's language.

Etiology

Research suggests that dyslexia has a genetic component and tends to run in families. If one or both parents has dyslexia, it is likely one of their children will have dyslexia due to inherited genes.Other risk factors include premature birth, low birth weight, and foetal exposure to environmental toxins.

Characteristics/Clinical Presentation

Diagnosis is based on subjective medical and social history, clinical observation, and a psychological assessment. There is no biological marker or chemical test to diagnose dyslexia. If there is a gap between a person's reading ability and their cognitive ability, dyslexia should heavily be considered. Early intervention is key to assisting children catch up to their age-level peers. Developmentally, children later diagnosed with dyslexia demonstrated difficulty with vocabulary and syntax acquisition as early as 36 months. Typically, by 5 years of age, more apparent and evident problems emerge with expressive vocabulary and letter knowledge.

When entering kindergarten, children with dyslexia will demonstrate difficulty with phonemes (smallest unit of speech distinguishing one word from another, such as: tap, tag, tan). Children in first grade will demonstrate difficulty with sight words, which are common words that children recognise without having to sound them out due to their frequent recurrence (e.g., the, he, at, there, my, two).

Educators and teachers provide strong feedback to parents and are pivotal with bringing forward any concerns regarding a child's reading abilities.

Medical Management

Dyslexia is a lifelong condition that does have a specific medication regimen or dietary supplementation. Depending on the age of the child and their respective grade level, a child can receive supportive services to assist them with reading. Research indicates that teaching should be completed by a tutor or reading specialist in smaller groups rather than larger groups of children.Lessons should focus on one of two phonemes per lesson and build up slowly on newly acquired skills.Evidence indicates that after school tutoring helps improve a child's reading potential significantly.

During the early years, phonics are introduced. Once mastered, children move on to reading comprehension. Following this achievement, kids progress to accuracy and speed of reading where words can be read quickly while simultaneously comprehending the objective of the text. Reading "maintenance" continues in the later school years. Modifications can be made in the classroom setting for children with dyslexia.

Physiotherapy Intervention

Although dyslexia is primarily addressed with further educational and speech related interventions, physiotherapy may be warranted. Depending on what co-morbidities are present with dyslexia, physiotherapy intervention may be warranted. For example, if a child is diagnosed with dyslexia and has developmental coordination disorder, physiotherapy may be warranted to address any functional deficits or anomalies.

There has been research done to determine if physical activity addresses any deficits children or adults with dyslexia may have. Generally, physical activity helps improve the reading ability of children at risk for dyslexia. Researchers believe it may have something to do with enhancing postural stability and dexterity, both skills necessary for reading. Little headway has been made as to why this physiological response occurs at the brain level.