What Is Developmental Dyslexia?

Is it just dyslexia?

Dyslexia is a language-based disorder affecting reading.  The underlying cause of dyslexia is a weakness that lies in the phonological part of the language system.  Our phonological skills allow us to hear and understand the sounds that make up our spoken language.  They let us manipulate these sounds and then relate the sounds to the letters or symbols that make up our written language.  This is a lifelong condition that is not acquired and is present from birth.  Since dyslexia is a localized weakness in the phonological system in the brain, children who have dyslexia have difficulty because the phonemes of language are less sharply defined. While this difficulty with phonological skills interferes with decoding, it does not interfere with the other language skills.  This is why bright children with strong language comprehension can be dyslexic.  The language skills needed for comprehension are not impacted.  Intelligence is not affected by dyslexia; many individuals with dyslexia also have IQ scores in the superior or gifted ranges.  

The term developmental dyslexia is also used as a term for what we think of as dyslexia: where the phonological weakness is the primary weakness.  This affects decoding, our ability to sound out words using letter-sound knowledge and letter pattern-sound knowledge, when we try to read single words accurately.  This can continue to affect a child or adult with dyslexia after the single word decoding has been remediated in the form of weak reading fluency.  Fluency is the ability to read with proper phrasing and expression at an appropriate rate.  Individuals who have dyslexia often have difficulty with reading fluency and can benefit from fluency instruction and practice.  

Of the other disorders that affect reading, one similar to developmental dyslexia is a language-learning disability.  A language-learning disability affects both the phonological system and the semantic language system.  This is also a disorder present from birth but it differs in that it affects scores of verbal intelligence.  Due to the difficulty with language, a child with a language-learning disability has difficulty with both the decoding and comprehension.  A child with a language-learning disability will also have difficulties with some other language skills, such as receptive language (understanding), expressive language (communication), retrieval (word finding), or articulation (speech and pronunciation).  

Posted on 10.Oct.21 in Struggling Readers

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