What Are the Different Types of Dyslexia?

Dyslexia is probably one of the most common neurobehavioral diseases in children, with an incidence of 5% to 18%. Dyslexia may behave differently in different language and writing systems, with a prevalence of about 3% to 10% in primary school children. For a long time, it has been thought that dyslexia mainly affects boys. Slavica et al. Conducted a retrospective cohort study of 5,718 children born between 1976 and 1982. Among them, the incidence of dyslexia in boys was about 2 to 3 times that of girls. In recent years, more data show that the number of men and women is almost equal. In previous statistics, the incidence of boys was higher, which was due to the bias of the sample selection in schools. Some longitudinal studies, whether prospective or retrospective, have suggested that dyslexia is a long-lasting state rather than a short developmental delay. The difference in reading ability between dyslexic and normal readers has remained relatively stable over time.

Cui Yonghua

(Deputy Chief Physician)

Department of Pediatrics, Beijing Anding Hospital, Capital Medical University

Dyslexia is a common learning disability among school-age children, accounting for about 4/5 of learning disabilities. Clinically, dyslexia is divided into acquired dyslexia and developmental dyslexia (DD). Acquired dyslexia refers to dyslexia caused by congenital or acquired brain damage and corresponding visual and hearing impairments. DD refers to the phenomenon that children with normal intelligence have no obvious neurological or organic damage during development, but their reading level is significantly behind their corresponding intellectual level or physiological age. Dyslexia in this article refers to DD.

Western Medicine Name: Dyslexia
Affiliated Department: Gynecology-Pediatrics

The main symptoms: Memorize letter obstacles, miss words when reading aloud
Multiple groups: School-age children
Contagious: Non-contagious

Dyslexia Overview

Advances in the etiology and pathogenesis of dyslexia

Dyslexia Research

Based on years of research on dyslexia, the West has formed three of the most influential theories, namely the theory of speech deficits, the general theory of perceptual deficits, and the cerebellum theory. Speech defect theory believes that DD suffers from speech representation, storage, and / or extraction defects, which in turn affects the form-to-speech conversion, resulting in poor speech skills and impaired reading ability. The general theory of sensory deficits is that dyslexia is caused by basic sensory deficits, including visual processing deficits and auditory processing deficits. Visual processing defects directly affect reading. Defects in auditory processing cause speech defects that affect reading. Cerebellar theory believes that the cerebellar dysfunction of people with dyslexia forms an automatic defect, which in turn affects the form-sound correspondence, resulting in a decline in children's reading ability. The cerebellum has many functions, such as individual motor balance, the formation of automation, blink reflexes, implicit learning, and time estimation.

Among the three major theories of dyslexia in pinyin text, the theory of phonetic defects predominates, that is, phonetic defects are the core defects of dyslexia. In China, Chinese is a non-phonetic text system. There is no form-phoneme correspondence rule. Phonetics cannot be reached directly from glyphs, but they can be communicated by the shape part. Moreover, speech does not necessarily play a necessary intermediary role in semantic access. Therefore, the theory of dyslexia in Pinyin text may not be suitable for people with Chinese dyslexia. Because the study of Chinese dyslexia started late, there is no mature theory.

Dyslexia Brain Research

In the past decade, with the development of technologies such as functional magnetic resonance imaging (fMRI) and event related potentials (ERP), great progress has been made in exploring the neural mechanisms of the dyslexia. Proponents of all three theories have searched for corresponding neurological evidence. The theory of speech deficiency believes that the dysfunction of the left cortex surrounding the left lateral fissure of the brain, especially the left temporal-parietal area and left inferior frontal dysfunction, causes speech defects and reduces reading ability. The general theory of perceptual deficits believes that the impaired visual and auditory processing of people with dyslexia is due to abnormalities in the large cell system. Cerebellar theory believes that the decline in reading ability of people with dyslexia is due to dysfunction of the cerebellum, and neurological studies did find abnormalities in the cerebellum of people with dyslexia.

Dyslexia genetic study

Genetic studies have shown that genetic factors have a great effect on dyslexia, but only if genes that affect dyslexia are found can a positive conclusion be reached. Recently, the Human Gene Naming Committee identified nine susceptibility loci: DYX1-DYX9 (DYX1, 15q21; DYX2, 6p21; DYX3, 2p16-p15; DYX4, 6q13-q16; DYX5, 3p12- q12; DYX6, 18p11; DYX7, 11p15; DYX8, 1p34-p36; DYX9, Xp27). Galaburda et al. [14] summarized 20 years of genetic research and found 4 susceptibility genes-DYX1C1, dyslexia KIAA0319, DCDC2, and ROBO1 interact with proteins encoded by them and are involved in neuronal migration and axon growth. The abnormal expression of these susceptible genes leads to abnormal nerve cell migration and axonal development, affecting the functions of the cerebral cortex and thalamus, further causing defects in perception, movement, and speech, which in turn affects reading.

Dyslexia clinical manifestations

Dyslexia in general clinical manifestations

In the alphabet writing system, the early stages of dyslexia may be manifested as obstacles such as recitation of letters, speaking the correct names of letters, sectioning of words, pronunciation analysis or classification. After that, I showed inadequacy in spoken reading: missed words, added words, misspelled words, misspelled words, replaced words when reading aloud, slow reading speed, long pauses or failure to correctly segment the words. There are also shortcomings in reading comprehension. You cannot recall what you have read, you cannot draw conclusions or inferences from the materials you read, and use common sense to answer questions in special stories you read. You cannot use the information in the stories. In the Chinese system, dyslexia is also manifested as: misreading of tones, pronunciation of similar structures (such as "fox" and "solitary"), misreading of polysyllabic words, and misreading of one of two words. Some children with dyslexia may also show some language deficits and cognitive impairments before school. For example, when copying pictures, they often cannot distinguish the relationship between the theme and the background. They cannot analyze the combination of figures, nor can they integrate the parts of the figure into a whole. School age may be accompanied by language skills disorders, spelling disorders, dyskinesias, etc .; often accompanied by ADHD and behavioral problems. More people with combined immunity and autoimmune disease than the normal population. There are many left-handed people, and the positive rate of nervous system software sign is high.

Dyslexia Course

It usually starts in infancy or childhood, and is obvious at 6-7 years old. Dyslexia can sometimes be compensated for in the lower grades. Significant increase only after 9 years of age. In mild cases, reading will gradually catch up after treatment, and there will be no signs of dyslexia in adulthood. In severe cases, despite treatment, many signs of the disorder persist for life. ^[1-5]

Dyslexia diagnosis

Refer to DSM-IV-TR for diagnostic descriptions and criteria for dyslexia.

Dyslexia description

Diagnostic features

The basic characteristic of dyslexia is that its reading achievement (such as reading correctness, speed, or comprehension ability in individualized standard tests) is significantly lower than its expected level of actual age, intelligence, and education (standard A). It can significantly affect an individual's academic achievement or activities that require reading skills in daily life (Criterion B). If an individual has other sensory defects, he or she may have difficulty reading beyond the level caused by sensory defects (criterion C). If there are neurological or other medical or sensory conditions, it should be diagnosed as axis III. Individuals with dyslexia (also known as dyslexia) have distortions, substitutions, or omitted sounds when reading aloud; at the same time, they have slower and misunderstanding characteristics when reading aloud and silently.

Accompanying Features and Defects

Mathematical and textual expression disorders often occur concurrently with dyslexia, and very few individuals experience situations in which there is only one of the two disorders without dyslexia.

Gender characteristics

60% to 80% of dyslexia is male. Existing referral procedures may be biased towards identifying male individuals, as they are more often accompanied by explicit disruptive behaviors along with learning disabilities. When we use more careful and rigorous criteria to diagnose dyslexia than based on the traditional school referral and diagnosis process, the incidence is more consistent between men and women.

Prevalence

Because many studies have focused on the prevalence of learning disabilities rather than on individual reading, math, and text expression disorders, the prevalence of dyslexia is difficult to establish. It is estimated that four out of every five individuals with a learning disability have a reading deficit, including individuals who develop alone or with a disability in mathematical writing. Its prevalence in the United States is about 4% of school-age children. In other countries where more stringent criteria are used to diagnose dyslexia, this prevalence may be reduced.

Course of disease

Although dyslexia (such as the inability to distinguish or recognize common letters from their pronunciation) may occur during kindergarten, dyslexia is rarely diagnosed at the end of kindergarten or just before elementary school, as it is rarely seen in schools Teach reading before the times. Especially when people with dyslexia are accompanied by a high IQ, such children's performance in the lower grades is usually within or close to the level of this grade, and dyslexia may not be obvious until the fourth grade or later. A relatively high proportion of individuals have a good prognosis with early diagnosis and early intervention. Dyslexia can persist into adulthood.

Dyslexia diagnostic criteria

A. Reading achievement such as reading correctness or comprehension in the individual standardized test is significantly lower than the expected performance of their actual age, intelligence, or education level.

B. The situation in Standard A significantly affects the individual's academic achievement or activities that require reading skills in daily life.

C. If an individual has other sensory defects, their reading difficulties will far exceed the levels caused by their sensory defects.

Note: If neurological or other medical or sensory problems occur, it should be diagnosed as axis III. ^[6-8]

Dyslexia treatment

Developmental dyslexia is a form of learning disorder, and its ultimate purpose is to correct it. With the deepening of research, people have a deep understanding of developmental dyslexia, and have formed some effective methods of correction and treatment. At present, the following models are used to correct developmental dyslexia:

Dyslexia intervention

Behavioral intervention basically uses the principle of operational conditioning to increase or decrease the frequency of target behaviors through appropriate environmental control of events associated with certain target behaviors of children. The significance of controlling the environment is to provide opportunities for specific behaviors. When conducting behavioral interventions, first of all, a detailed analysis of the premise and consequences of behaviors is often required. This is often based on direct observations. Secondly, in identifying those problems that may cause or strengthen the problems we want to overcome, the main test must create A stable, structured intervention environment; again, the rules of intervention must be clear and consistent, appearing in as positive a form as possible, and not in a single prohibited form. In addition, the requirements for children with dyslexia should be few and clear for a period of time, and feedback should be guaranteed at any time.

- Dyslexia cognitive-behavioral intervention

Cognitive-behavioral intervention emphasizes that children with dyslexia develop an active, self-regulating learning style. Cognitive behaviorists believe that individuals can control their own behavior, and the appearance of behavior does not depend solely on environmental stimuli or behavioral consequences. During the reading process, the negative and passive performance of children with dyslexia hinders their potential development. The cognitive-behavioral intervention model advocates cognitive strategy training or self-directed training for children with dyslexia.

(1) Cognitive strategy training

Studies have found that an important problem for children with learning disabilities is that they lack certain effective cognitive strategies or do not choose appropriate strategies. The basic process of cognitive strategy training is as follows: evaluate the current strategies of children with dyslexia, identify the disadvantages of these children, and establish the target strategies to be trained; explain the target strategies to children; demonstrate the use of target strategies Speech rehearsal; Provide low-difficulence materials, conduct controlled exercises and give feedback; Provide reading materials with age-difficult children with dyslexia, practice and give feedback; evaluate strategies for children with dyslexia, And guide children to learn how to choose the appropriate strategy according to the task; realize the transfer in actual learning.

(2) Self-directed training

The central idea of self-directed training is to train children to actively use self-directed speech to monitor their behavior until a certain task is completed. This training should guide children with dyslexia to set reading goals. The goals set should be specific and challenging. Such clear and realistic goals can stimulate the reading motivation of children with dyslexia and focus on the tasks that must be completed. Progress in pursuing desired goals also promotes one's sense of accomplishment. The identification of self-directed speech is also important in training. This self-directed speech can be voiced or silent, and is used to guide or regulate one's behavior. The content and order of speech depends on the task to be accomplished, but sentences are best created by children with dyslexia themselves. During the reading process, children with dyslexia need to look at the use of reading strategies and some specific behavioral performances, and run through the previously prepared self-speech. Self-speaking guided reading activities are carried out in accordance with steps and established strategies, and serve as a reminder and urge correction when errors or deviations occur. Before letting children monitor themselves, trainers need to explain how. In the first few times, the trainer needs to observe the child's self-monitoring situation, praise the child's correct behavior in time, and then gradually withdraw external monitoring.

The main characteristics of cognitive-behavioral training are as follows: try to guide children as active participants in their own learning process; attach importance to the use of demonstration target strategies and methods; and use children's external speech as an intermediary. These characteristics can ensure that children with dyslexia control their reading and learning process and change their original negative and reactive style.

Dyslexia functional training

This training is also mental process training. This is a learning disorder intervention method designed from the assumption of the pathological mechanism of psychological process disorder. The founders of this model believe that learning relies on advanced functions of the nervous system, and the realization of these advanced functions is based on psychological processes such as basic perception. Therefore, training basic mental processes can improve brain function and thus academic performance. In recent years, in countries and regions such as Japan and Taiwan, a method of functional training of the nervous system called "sensory integration training" has been used to a certain extent. This method was developed by Iris. She regards the integration of sensory information, that is, sensory integration as a key function of the nervous system, and believes that sensory integration disorders with vestibular system disorders as the core cause patients with poor control of muscle movement, lack of spatial cognition, and input of physical sensory information. Impaired processing, resulting in obstacles to listening, reading, writing, calculating and communication, and making it difficult to benefit from general intervention training. Only through sensory integration training to improve the organization of sensory information can the problem of dyslexia be overcome.

Dyslexia peer guidance

Peer coaching is the method by which students teach students. This is a new training model that emerged in the mid-1980s. In terms of cognition, peer guidance stimulates the motivated learners' learning. Their attitudes to learning have changed, they are interested in the subject being taught, and they may even change their attitudes towards learning and school. In terms of socialization, the mentee learned a lot of interpersonal skills from peer mentors, improved peer relationships, and promoted the development of self-awareness. The specific process of this model is: first select some children as mentors and introduce them to their dyslexic peers; then conduct special training for the mentor to teach them the content and methods that need to be taught to dyslexic peers; Then arrange peer coaching activities, usually at least once a week. This model can be one-to-one, but more often it takes the form of several mentors and peers working together. Teachers are not only responsible for the formation of peer groups and training mentors, but also for further training of the mentors, or additional guidance for the mentees.

The peer guidance method is not applicable to all learning content and children. It cannot be used for difficult course content and children with significant externalized behavior problems.

Dyslexia biochemistry and medication

Biochemical and drug treatment is the use of medication to control and improve the physical condition of children with dyslexia, and then improve their learning status. A lot of research has been done on the after-effects of drug treatment, and it has been found that these drugs have a certain effect in treating dyslexia, but their therapeutic effect is limited and should be used with caution.

The above several correction modes have their own advantages and disadvantages, and the teaching intervention for children with dyslexia should not be limited to only one correction mode, but should be compatible and inclusive. ^[9-16]