The biochemical and cognitive explanation of developmental dyslexia

Abstract

There is increasing evidence that biochemistry, genetics and cognitive deficits play a part in the etiology of developmental dyslexia (DD). The developmental dyslexia\reading disability (RD) that is part of a larger heterogeneous group of learning disorders, and characterized by unexpected problems in academic performance, despite average intelligence. However, controversy still surrounds both the identification and management of this condition, and while its etiology is recognized as being complex and multifactorial, yet little progress has been made in elucidating predisposing factors at the biological level. The purpose of this review is to explore the possibility of dyslexia that falls within biochemical and cognitive spectrum of disorder. Based on the biochemical evidence, there is a necessity for further research into the role of fatty acids in developmental dyslexia that contributed with an abnormal metabolism of HUFA in fetal brain development, or the maintenance of normal brain function. Currently, the molecular geneticists have been seeking to identify the actual genes underlying developmental dyslexia. Nine loci were found to be associated with susceptibility to dyslexia (DYX1 to DYX9). Those have contained important four candidate genes associated with dyslexia that would aid in distinguishing between children whose reading problems are caused primarily by cognitive deficits with biological origin. Accordingly, the cognitive deficits of dyslexia will be presented in the domains of phonological, auditory processing, visual, magnocellular and automaticity/cerebellar deficit theories. Understanding the biochemical and cognitive basis of dyslexia may help us plan our future research.

Keywords

Dyslexia - biochemistry - cognitive - phonological - auditory - visual - magnocellular - automaticity/cerebellar - multifactorial deficit model