Dyslexia
Introduction[edit | edit source]
Dyslexia is a prevalent learning disability of neurobiological in origin. It is characterized by a child's difficulty with reading, writing, and spelling. The difficulty is due to 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.[1] People with dyslexia can also demonstrate poor spelling and decoding abilities.[2] It is the most common neurocognitive disorder.
Definition[edit | edit source]
People with developmental dyslexia demonstrate difficulty with reading, word recognition, and spelling despite exhibiting age-appropriate intelligence and sensory abilities.[3]People with dyslexia are unable to decipher or decode what they are reading. Comprehension is usually intact. People with dyslexia will have trouble matching and combining letters on a page to sound out words. 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.[4]
Children and adults with dyslexia have difficulty with phonological processing, or the ability to quickly and correctly hear, store, recall, and make different speech sounds. They also have difficulty with spelling and rapid visual-verbal responding.[4]This becomes more evident with failed attempts to blend letters to sound out words, incorrect spelling, and difficulty verbalizing 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.[5]
Prevalence[edit | edit source]
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.[1] In the United Kingdom, 10% of the population is believed to be dyslexic.[6] There is a relatively small male skewed dominance diagnosed with dyslexia than female (1.5-3:1).[3]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[edit | edit source]
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 or problems 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.[3]
Etiology[edit | edit source]
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.[7]Other risk factors include premature birth, low birth weight, and fetal exposure to environmental toxins.
Characteristics/Clinical Presentation[edit | edit source]
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.[8]
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 recognize without having to sound them out due to their frequent recurrence (e.g., the, he, at, there, my, two).[8]
Educators provide strong feedback and are pivotal with bringing forward any concerns regarding a child's reading abilities.
Physical Therapy Intervention[edit | edit source]
Resources[edit | edit source]
References[edit | edit source]
- ↑ 1.0 1.1 The Yale Center for Dyslexia and Creativity. Dyslexia FAQ [Internet]. Yale Dyslexia. 2017. Available from: https://dyslexia.yale.edu/dyslexia/dyslexia-faq/
- ↑ International Dyslexia Association. Definition of Dyslexia [Internet]. International Dyslexia Association. 2002. Available from: https://dyslexiaida.org/definition-of-dyslexia/
- ↑ 3.0 3.1 3.2 Peterson RL, Pennington BF. Developmental dyslexia. The lancet. 2012 May 26;379(9830):1997-2007.
- ↑ 4.0 4.1 Shaywitz S. Yale Dyslexia [Internet]. Yale Dyslexia. 2017. Available from: https://dyslexia.yale.edu/dyslexia/what-is-dyslexia/
- ↑ Defining Dyslexia [Internet]. National Center on Improving Literacy. 2017. Available from: https://improvingliteracy.org/brief/defining-dyslexia
- ↑ British Dyslexia Association. Dyslexia - British Dyslexia Association [Internet]. British Dyslexia Association. 2019. Available from: https://www.bdadyslexia.org.uk/dyslexia
- ↑ Dyslexia: What It Is & What Causes It | ABF [Internet]. American Brain Foundation. Available from: https://www.americanbrainfoundation.org/diseases/dyslexia/
- ↑ 8.0 8.1 Munzer T, Hussain K, Soares N. Dyslexia: neurobiology, clinical features, evaluation and management. Translational Pediatrics. 2020 Feb;9(Suppl 1):S36.
