The dyslexia It is a specific difficulty of learning of neurobiological origin that occurs in children and adults. It is characterized by a difficulty in Accuracy / fluency of word recognition and poor spelling and decoding skills.
In addition, it may Other secondary consequences such as problems of comprehension or reduction of the reading experience that may hinder the acquisition of vocabulary and Acquisition of other basic knowledge (International Dyslexia Association, 2016).
The terms Reading learning disorder Y dyslexia they're synonyms. In general, all children learn to Read without specific difficulties; But approximately 25% may experience some type of acquisition problem at some point in their stage school. However, only a very small group is diagnosed dyslexia (Matute, Ardila and Roselli, 2010).
The main characteristic of dyslexia is the difficulty in learning to read, despite this, not all children who have problems Develop this learning are diagnosed with dyslexia (Matute, Ardila and Roselli, 2010).
Although it affects a significant part of the child population and is considered one of the most alarming causes of school failure, there is no Generalized agreement about their etiology, cognitive mechanisms involved, and even about their categorical characterization (Artigas-Pallarés, 2009).
Current scientific trends suggest that this disorder has an obvious neurobiological and genetic basis and that at the cognitive level is a consequence Of a failure in the phonological processing that we perform of the information (López-Escribano, 2007).
What is dyslexia?
Already at the end of the 19th century, the first observations were made of people of child age who presented difficulties in learning the Reading (Matute, Ardila and Rosselli, 2010).
It is in this period when the first descriptions of patients who after a brain injury acquire a disorder of the reading, What was he called alexia (Matute, Ardila and Rosselli, 2010).
On the other hand, Orton's research during the first decades of the last century, highlighted the tendency to rotations and investments of Symbols, observed in many of the children with learning problems of reading. In addition, he pointed out the prevalence of lefthander in these children or the Existence of a mixed laterality (Matute, Ardila and Rosselli, 2010).
In the final decades of the twentieth century, the first definition of dyslexia that gives a clinical status, from which three points Essential Matute, Ardila and Rosselli, 2010):
- The socio-cultural and school context are not responsible for the specific reading disorder.
- There are difficulties in the cognitive sphere that affect the learning of reading.
- The disorder has a biological origin.
In these ways, all these characteristics have been defined in the current definition of dyslexia:
"Dyslexia is a specific learning disorder whose origin is neurobiological. HE
Characterized by difficulties in accuracy and / or fluency in word recognition and poor spelling and decoding skills. These difficulties typically result from a deficit in the phonological component of language that is often unexpected in relation to other cognitive habilyties And to the school instruction received. Secondary consequences include problems in reading comprehension and reduced reading experience that limit vocabulary growth and information management" (International Dyslexia Association, 2016).
Dyslexia affects those who have it throughout their lives; However, the impact can be modified at different stages. Can make it difficult Achievement of academic success and in severe ways, may require special educational accommodations or additional support services (International Dyslexia Association, 2016).
Therefore, dyslexia is a type of disorder that specifically affects a person's reading ability. These individuals often Reading level lower than expected for their age level and overall intellectual performance (National Institute of Neurological Disorders and Stroke, 2015).
Although it is a heterogeneous disorder, the characteristics common to all people with dyslexia are (National Institute of Neurological Disorders and Stroke, 2015):
- Difficulties in phonological processing (manipulation of sounds).
- Spelling.
- Rapid verbal / visual response.
How many people have dyslexia?
Learning Disorder in Reading accounts for approximately 80% of the cases of people with learning disabilities. Different studies Have pointed out that this is the most prevalent learning disorder (Matute, Ardila and Roselli, 2010).
The international dyslexia association points out in the United States approximately 13-14% of the school-age population has some Condition susceptible of special education. Of these, about half, are characterized by learning disorders and in addition, 85% Present difficulties in reading and language learning (International Dyslexia Association, 2016).
Despite this, it is estimated that around 15-20% of the population as a whole, present some symptoms of dyslexia, of which not all will be Diagnosed with this condition (International Dyslexia Association, 2016).
In general, it is accepted that dyslexia presents a prevalence of between 5 to 17.5% and that can be observed in different countries. Despite this, The specific characteristics of a language and its orthographic system may have different effects on the presence of this disorder (Matute, Ardila And Roselli, 2010).
In the case of the Spanish-speaking population, it is considered that the prevalence of dyslexia may be less because the linguistic system is quite Simple and regular (Matute, Ardila and Rosselli, 2010).
On the other hand, it has been observed that dyslexia occurs more frequently in children than in girls, with a ratio of 1.5 to 1 (Matute, Ardila and Roselli, 2010).
As for the age, there are notable variations in the different theoretical positions. On the one hand, the delay hypothesis considers the delay in Reader performance disappears as age and school level increases, while the deficit hypothesis considers that this reading deficit is going to Maintain throughout life (Matute, Ardila and Roselli, 2010).
Dyslexia can occur in people of all origins and even intellectual levels (International Dyslexia Association, 2016). In spite of Prevalence can also be affected by children's contact with written texts, the development of metalinguistic awareness, the Recognition of letters or the ability of phonological segmentation (Matute, Ardila and Roselli, 2010).
Causes of dyslexia
Studies in the area of learning disorders show that dyslexia appears to have a complex genetic and environmental basis. In lines In general, genetic factors may account for between 30-70% of the variability of reading ability (Benitez-Burraco, 2007).
The family history of the disorder is considered the most important risk factor. In particular, one study has shown that between 35-40% of First-degree relatives of children with dyslexia are also affected by this disorder. In addition, almost 30% of families in Diagnosed to any of its members, presents at least one other affected member (Matute, Ardila and Roselli, 2010).
On the other hand, regarding the percentage of variability that does not correspond to the genetic level, some exogenous factors of origin have been identified, Among which are: the presence of complications during pregnancy or childbirth; The disease of some type of infection during the Embryonic; Hormonal alterations, epilepsy , Among others (Matute, Ardila and Rosselli, 2010).
In addition, different structural and functional neuroimaging studies have shown differences in both the way of functioning and development Of people with dyslexia (International Dyslexia Association, 2016).
Through different Positron emission tomography (PET) and functional magnetic resonance imaging (MRI) has shown abnormalities Cortical microscopes that reduce the connectivity between different areas of the cerebral cortex . In addition, these techniques locate the location of Dysfunctional brain areas in two areas of the left hemisphere : Parietal-temporal region and the temporo-occipital region (Matute, Ardila and Roselli, 2010).
In addition, there are compensatory mechanisms related to areas near the lower frontal gyrus of the two hemispheres, in addition to the region Occipital-temporal, related to word recognition (Matute, Ardila and Roselli, 2010).
What are the effects of dyslexia?
The impact of specific reading disorder is different for each person and depends heavily on severity and interventions The main problems that people with dyslexia have are difficult to recognize words, Reading fluency and in some cases difficulty in spelling and writing (International Dyslexia Association, 2016).
In many cases, they may also present problems in expressive language even if they are exposed to good models of language in their family contexts and School. Difficulties may arise in expressing oneself clearly or in order to understand the totality of messages emitted by others (International Dyslexia Association, 2016).
Although it is difficult to recognize or identify some of these language problems on a number of occasions, they may trigger consequences Important at school, work or social level. In addition, can also affect the person image itself, many students come to Feeling less capable, underestimating both their abilities and their potential abilities (International Dyslexia Association, 2016).
What cognitive and lingual components affect dyslexia?
The analysis of the neuropsychological processes involved in the development of dyslexia, we must refer to the level of comorbidity. In general, Reading disorder is most frequently associated with writing disorder or writing. They will share common characteristics and (Dementia, low self-esteem, efficacy, etc.) (Matute, Ardila and Roselli, 2010).
In addition, if we refer to the etiological diagnosis, dyslexia may appear to be associated with medical diseases, so that cognitive difficulties And linguistics will be associated with the syndrome in question (Matute, Ardila and Roselli, 2010).
In relation to the cognitive components involved in dyslexia, a large number of theories have been proposed that involve deficits in the Rapid auditory processing, visual processing, cerebellar involvement, automation deficit, magnocellular system deficit, in The processing of temporal order or motor deficits. However, currently the phonological awareness to be the clearest predictor of the Reading skills (Matute, Ardila and Rosselli, 2010).
In addition, there are also other cognitive and / or linguistic functions that relate to reading learning: ability to decode Visual stimuli, naming speed, vocabulary amplitude, operative memory capacity, Attention Y concentration (Matute, Ardila and Rosselli, 2010).
When is a child suffering from dyslexia?
The diagnostic criteria Diagnostic and Statistical Manual of Mental Disorders I-V , Refer to the following conditions:
Criterion A : A reading performance (ie, accuracy, speed or reading comprehension assessed by standardized tests administered Individually), which is substantially lower than expected in terms of chronological age, intelligence quotient and schooling Typical of the individual's age. Oral reading is characterized by distortions, substitutions or omissions; Both oral and silent reading are Characterized by slowness and errors in understanding.
Criterion B : Altering reading significantly interferes with academic performance or certain activities of daily living that require
Reading skills.
Criterion C : If a sensory deficit is present, difficulties in reading exceed those usually associated with it. If there is an illness Neurological or medical impairment or a sensory deficit, should be coded in Axis III.
Is it possible to treat dyslexia?
Dyslexia is a type of disorder that is going to present throughout the life of the people who suffer it. With an efficient intervention, in Many of the cases develop an optimal learning of reading and writing (International Dyslexia Association, 2016).
Early identification and early treatment is essential to achieve control of deficits and successful adaptation to different levels Academics.
In many cases it will be necessary the intervention of a specialized therapist who uses different multisensory strategies for the work with the Reading difficulties. It is important that the intervention is performed through a systematic method involving several senses (International Dyslexia Association, 2016).
Students with dyslexia often require repeated feedback and a high amount of practice to develop correctly and Effective word recognition skills (International Dyslexia Association, 2016).
Academic modifications are often applied to facilitate curriculum success. Students with dyslexia often require more time To complete assignments or note-taking aids (International Dyslexia Association, 2016).
References
- Artigas-Pallarés, J. (2009). Dyslexia: disease, disorder or something different. Rev Neurol, 48 (2), 63-39.
- Benitez-Burraco. (2007). Molecular bases of dyslexia. Rev Neurol, 45 (8), 491-502.
- GOING. (2016). Dyslexia Basic . Retrieved from the Internatinoal Dyslexia Association: http://eida.org/
- López-Escribano, C. (2007). Contributions of neuroscience to the diagnosis and educational treatment of developmental dyslexia. Rev Neurol, 44
(3), 173-180. - Rosselli, Mónica; Matute, Esmeralda; Alfredo, Ardila;. (2010). Neuropsychology of Child Development. Mexico: The Modern Manual.
- Soriano-Ferrer, M. (2004). Educational implications of the cognitive deficit of evolutionary dyslexia. Rev Neurol, 38 (1), 47-52.