Diseases and Disorders

Dyslexia: A Summary

Alexander Skvortsov


Introduction

The ability to communicate with other creatures is and has been an enormous advantage to any species that can master it. From primitive mating calls to more complex whistles to full-fledged language, communication allows for organisms to work with each other, accomplishing as a unit what could not be done as an individual. Much of human societal evolution would be impossible without language; not the agricultural revolution, nor urban development, or any other major human social accomplishment. Among other advanced mental capabilities, the capacity to communicate through the use of a complex alphabet is integral to humanity. In today’s modern society, this ability to communicate is more important than ever.  This ability is hindered by dyslexia, a learning disorder which may heavily impair comprehension and expression of language, experienced by approximately 15% of the population.

 

Overview and Symptoms

    Dyslexia is a developmental learning disorder. The primary manifestation of which is a difficulty learning and comprehending language, particularly written language, and is characterized by abnormal difficulties with reading despite average or above average performance on various other intellectual and academic metrics. Students with dyslexia will often appear to be brighter, more intellectually developed, and conceptually advanced than their non-dyslexic peers; however, their reading level often places below grade average. For these reasons, dyslexia is traditionally classified as a cognitive process disorder rather than an intelligence disorder: Dyslexics do not seem to exhibit intellectual impairments as a character or their disease.

    As with most conditions, severity of dyslexia can vary from a minor inconvenience to a debilitating impairment. Onset of dyslexia almost always occurs from early childhood, and can be often noticed by excessively slurred speech, confusion while reading, problems in regards to phonological awareness: the ability to understand and comprehend sounds, and the almost universally present difficulties with reading. In rare cases of adult-onset dyslexia, the disease is generally trauma-related, or appears in accordance with another neurological disease.

 

Causes

    Dyslexia is considered to have basis in both genetics and neurology. Studies have shown that dyslexia commonly runs in families, with over 50% of cases thought to be inherited [1]. Genetic causes for dyslexia have been discovered in about 9 genes [1] on Chromosomes 6 and 15 [2]. Neurological discrepancies have been discovered as well. Post-mortem studies have noted anatomical differentiations between the brains of dyslexics and those of non-dyslexics, particularly in the corpus callosum, which links the two cerebral hemispheres. Also in the planum temporale, a triangular area which forms the core of Wernicke’s area, and it is thought to be heavily involved in processing of language. Anatomical differences have also been found by fMRI scans throughout the left hemisphere [2].

 

Diagnosis

    Diagnosis of dyslexia can often be difficult due to lack of a clear, objective definition. Trouble with reading often occurs on a spectrum, with no definitive differentiation between dyslexia and natural issues with reading. Various characteristics that seem to indicate dyslexia are often misleading. For example, people often associate conditions such as seeing or reading backwards with dyslexia. However, these symptoms are actually quite common with young children just learning to read [3]. Characteristics of dyslexia include prolonged trouble reading, despite average achievement in other fields, and other literary issues. Dyslexia should be evaluated by an educational psychologist, neurologist, or other qualified medical professional.

 

Pathophysiology

    The process of reading is a complicated combination of two distinct neural operations: orthological reading and phonological reading. Orthological reading is based upon direct association of a word with a concept, and is very direct. Orthological processes are most often used for commonly used words. Phonological reading, in contrast, uses a conversion of written text into sounds, combination of sounds, and then association of the resulting word with a concept. Research suggests that a subset of dyslexia, phonological dyslexia, is rooted in mis development of the phonological reading system [2].

    Research points to three major neural areas associated with reading: Broca’s Area, Wernicke’s Area, and the Left Occipito-Temporal region. Studies have demonstrated that children suffering from dyslexia show considerably less activation in these three areas while reading than children without dyslexia. The Left Occipital-Temporal region seems to be especially different in dyslexics as compared to non-dyslexics.

 

Prognosis

    Although dyslexia can severely impact lives of affected individuals, it can be overcome to a degree in most cases. While the disease is not curable, there exist a variety of treatment plans focused primarily around reshaping a child’s education and introduction to reading. A large effort is often required; however, progress can often be made. Individuals suspecting themselves, relatives, or friends of having dyslexia should consult a trained educational psychologist, neurologist, or other medical professional.


References


  1. Debunking the myths about dyslexia. (2016). University Of Michigan. http://dyslexiahelp.umich.edu/dyslexics/learn-about-dyslexia/what-is-dyslexia/debunking-common-myths-about-dyslexia. Retrieved: 11/23/2016

  2. Siegel, L. S. (2006). Perspectives on dyslexia. Paediatrics and Child Health, 11(9), 581–587. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2528651/. Retrieved:

  3. What causes dyslexia? Dyslexia, http://www.dyslexic.org.uk/about-dyslexia/what-causes-dyslexia. Retrieved: 11/23/2016

Alexander Skvortsov

Alexander Skvortsov


Hello world!