Dyslexia is a general term used to describe a common learning disorder in which the affected person’s ability to read and write is impaired. What are the most common causes of dyslexia?
Dyslexia in children
Children affected by dyslexia have difficulty identifying stem words, making it difficult for them to determine the order in which letters should follow each other in words. Children with dyslexia may have normal vision and intellectual abilities, meaning that the condition often goes unnoticed and unrecognised in adolescence and even into adulthood.
Most children with dyslexia can go on to do well in school if they receive emotional support, tutoring and educational programmes tailored to their specific needs. The diagnosis of dyslexia is based on intellectual, psychological, educational, medical, speech and language assessment.
Genetic predisposition
The exact cause of dyslexia is not clear, although it is generally believed that the condition runs in families. As such, dyslexia appears to be a hereditary condition, and children with a family history of literacy learning difficulties are more likely to develop dyslexia than children without such a family history.
Other factors have also been identified that may contribute to the severity of the condition.
For example, six different genes have been identified as potentially increasing the risk of dyslexia. Four of these genes are thought to be involved early in the brain formation process called neuronal migration, which leads to the development of specialised areas of the brain.
Most experts agree that dyslexia is associated with dysfunctions in areas of the left hemisphere brain that are involved in language comprehension, including Wernicke’s motor speech area and sound/speech production, or Broca’s motor speech area.
Acquired dyslexia
In a minority of cases, dyslexia develops after birth, usually as a result of a stroke, brain injury or other form of brain trauma.
Phonological processing
Phonological processing refers to the ability to understand how words are made up of smaller units of sounds or ‘phonemes’.
As infants, people have a natural ability to recognise words, which helps them to learn language. However, these words are often recognised as a single sound rather than being broken down into component sounds. For example, the word “fridge” will be recognised as having a specific sound and will not need to be broken down into the components “lo” – “dó” – “wka” in order for the child to understand it. However, this is not the case when a child is learning to read or write.
Literacy development depends on phonological processing, which is defined as the child’s ability to recognise letters, combine them into phonemes and use these phonemes to form or interpret a word. Brain scans suggest that the cause of dyslexia is a reduced ability to process words in this way due to changes in the development and function of certain parts of the brain.
Causes of developmental dyslexia include:
- genetics,
- micro-damage to the central nervous system,
- lack of mastery of basic reading and writing techniques,
- disorders of the lateralisation process,
- hormonal causes,
- emotional disorders,
- disorders of the pace and rhythm of development.
Sources:
- http://www.psychologia.edu.pl/czytelnia/50-artykuly/699-dysleksja-8211-charakterystyka-zjawiska.html
