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You are here: Home > Information > General Information about Dyslexia > Causes

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A great deal of research has been done in recent years on the cause of dyslexia and it may be that a great deal more needs to be done before we have a definitive answer.  We do know that developmental dyslexia is inherited, only slightly more common in males than females and that one is born with it.  While no conclusive research has been carried out in Ireland to determine how prevalent it is, studies in other countries would suggest that approx. 8-10% of the population are likely to be affected.  It would seem that people with dyslexia share a cluster of genes, which may, it is believed, account for the variations in the nature and extent of specific learning difficulties.

Experts are not agreed, however, on the underlying causes of dyslexia.  The prevalent research considers that a phonological deficit is the root cause of dyslexia.  Evidence from brain imaging suggests that people with dyslexia do not activate the left hemisphere (the language side) in the brain as much when reading as non-dyslexic readers, and that there is less engagement of the areas of the brain which match letters with sounds.

Professor John Stein, Oxford, believes that auditory and visual difficulties are caused by abnormal magnocellular development.  Malfunction in the development of sensory nerves happens at the foetal stage and is said to cause eye convergence difficulties and inhibit steady eye fixation.

Yet another view is that the role of the part of the brain which controls balance (the cerebellum) is crucial and that differences in this area make it difficult for children with dyslexia to acquire automaticity in tasks and may further inhibit the development of language dexterity and motor skills.

Experts do agree that dyslexia describes differences in the way in which the brain processes information, and while there may be differences in the way in which the brain works, this does not imply any abnormality, disease or defect.

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