HOME

TheInfoList




Dyslexia, also known as reading disorder, is a disorder characterized by difficulty
reading Reading is the process of taking in the sense or meaning of letters, symbols, ''etc.'', especially by sight or touch. For educators and researchers, reading is a multifaceted process involving such areas as word recognition, orthography (spelli ...

reading
in individuals with otherwise unaffected
intelligence Intelligence has been defined in many ways: the capacity for abstraction Abstraction in its main sense is a conceptual process where general rules and concept Concepts are defined as abstract ideas or general notions that occur in the mind, ...
. Different people are affected to different degrees. Problems may include difficulties in
spelling Spelling is a set of conventions that regulate the way of using s (writing system) to represent a language in its . In other words, spelling is the rendering of speech sound (phoneme) into writing (grapheme). Spelling is one of the elements of , ...

spelling
words, reading quickly, , "sounding out" words in the head, pronouncing words when reading aloud and understanding what one reads. Often these difficulties are first noticed at school. When someone who previously could read loses their ability, it is known as "alexia". The difficulties are involuntary and people with this disorder have a normal desire to
learn Learning is the process of acquiring new understanding, knowledge, behaviors, skills, value (personal and cultural), values, attitudes, and preferences. The ability to learn is possessed by humans, animals, and some machine learning, machines; t ...

learn
. People with dyslexia have higher rates of
attention deficit hyperactivity disorder Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by inattention, or excessive activity and impulsivity, which are otherwise not Developmental psychology, appropriate for a person's age. Some indivi ...
(ADHD),
developmental language disorder Developmental language disorder (DLD) is identified when a child has problems with language development that continue into school age and beyond. The language problems have a significant impact on everyday social interactions or educational progress ...
s, and difficulties with numbers. Dyslexia is believed to be caused by the
interaction Interaction is a kind of action that occurs as two or more objects have an effect upon one another. The idea of a two-way effect is essential in the concept of interaction, as opposed to a one-way causal effect. Closely related terms are interac ...
of and environmental factors. Some cases run in families. Dyslexia that develops due to a
traumatic brain injury A traumatic brain injury (TBI), also known as an intracranial injury, is an injury to the brain caused by an external force. TBI can be classified based on severity (ranging from mild traumatic brain injury TBI/concussionto severe traumatic ...
,
stroke A stroke is a medical condition A disease is a particular abnormal condition that negatively affects the structure or function (biology), function of all or part of an organism, and that is not due to any immediate external injury. Di ...

stroke
, or
dementia Dementia manifests as a set of related symptoms, which usually surface when the brain is damaged by injury or disease. The symptoms Signs and symptoms are the observed or detectable signs, and experienced symptoms of an illness, injury, or ...
is called "acquired dyslexia". The underlying mechanisms of dyslexia result from differences within . Dyslexia is diagnosed through a series of tests of memory, vision, spelling, and reading skills. Dyslexia is separate from reading difficulties caused by
hearing Schematic diagram of the human ear Hearing, or auditory perception, is the ability to perceive Sound, sounds through an organ, such as an ear, by detecting Vibration, vibrations as periodic changes in the pressure of a surrounding medium. Th ...
or
vision problem Visual impairment, also known as vision impairment or vision loss, is a decreased ability to see to a degree that causes problems not fixable by usual means, such as glasses Glasses, also known as eyeglasses or spectacles, are vision eyewe ...
s or by insufficient
teaching Education is the process of facilitating learning Learning is the process of acquiring new understanding, knowledge, behaviors, skills, value (personal and cultural), values, attitudes, and preferences. The ability to learn is possessed ...
or opportunity to learn. Treatment involves adjusting teaching methods to meet the person's needs. While not curing the underlying problem, it may decrease the degree or impact of symptoms. Treatments targeting vision are not effective. Dyslexia is the most common
learning disability Learning disability, learning disorder, or learning difficulty (British English) is a condition in the brain that causes difficulties comprehending or processing information and can be caused by several different factors. Given the "difficult ...
and occurs in all areas of the world. It affects 3–7% of the population; however, up to 20% of the general population may have some degree of symptoms. While dyslexia is more often diagnosed in men, it has been suggested that it affects men and women equally. Some believe that dyslexia should be best considered as a different way of learning, with both benefits and downsides.


Classification

Dyslexia is divided into developmental and acquired forms. This article is primarily about ''developmental dyslexia'', i.e., dyslexia that begins in early childhood. Acquired dyslexia occurs subsequent to neurological insult, such as
traumatic brain injury A traumatic brain injury (TBI), also known as an intracranial injury, is an injury to the brain caused by an external force. TBI can be classified based on severity (ranging from mild traumatic brain injury TBI/concussionto severe traumatic ...
or
stroke A stroke is a medical condition A disease is a particular abnormal condition that negatively affects the structure or function (biology), function of all or part of an organism, and that is not due to any immediate external injury. Di ...

stroke
. People with acquired dyslexia exhibit some of the signs or symptoms of the developmental disorder, but requiring different assessment strategies and treatment approaches.


Signs and symptoms

In early childhood, symptoms that correlate with a later diagnosis of dyslexia include delayed onset of speech and a lack of phonological awareness. A common myth closely associates dyslexia with mirror writing and reading letters or words backwards. These behaviors are seen in many children as they learn to read and write, and are not considered to be defining characteristics of dyslexia. School-age children with dyslexia may exhibit signs of difficulty in identifying or generating rhyming words, or counting the number of syllables in words–both of which depend on
phonological awareness Phonological awareness is an individual's awareness of the phonological Phonology is a branch of that studies how languages or dialects systematically organize their sounds (or constituent parts of signs, in sign languages). The term also r ...
. They may also show difficulty in segmenting words into individual sounds or may blend sounds when producing words, indicating reduced
phonemic awareness Phonemic awareness is a subset of phonological awareness in which listeners are able to hear, identify and manipulate phonemes, the smallest mental units of sound that help to differentiate units of meaning (morphemes). Separating the spoken word ...
. Difficulties with word retrieval or naming things is also associated with dyslexia. People with dyslexia are commonly poor spellers, a feature sometimes called dysorthographia or
dysgraphia Dysgraphia is a deficiency in the ability to write, primarily handwriting Handwriting is the writing done with a writing instrument, such as a pen or pencil, in the hand. Handwriting includes both block letters, printing and cursive styles and ...

dysgraphia
, which depends on orthographic coding. Problems persist into adolescence and adulthood and may include difficulties with summarizing stories, memorization, reading aloud, or learning foreign languages. Adults with dyslexia can often read with good comprehension, though they tend to read more slowly than others without a learning difficulty and perform worse in
spelling Spelling is a set of conventions that regulate the way of using s (writing system) to represent a language in its . In other words, spelling is the rendering of speech sound (phoneme) into writing (grapheme). Spelling is one of the elements of , ...

spelling
tests or when reading nonsense words–a measure of phonological awareness.


Associated conditions

Dyslexia often co-occurs with other learning disorders, but the reasons for this comorbidity have not been clearly identified. These associated disabilities include: *
Dysgraphia Dysgraphia is a deficiency in the ability to write, primarily handwriting Handwriting is the writing done with a writing instrument, such as a pen or pencil, in the hand. Handwriting includes both block letters, printing and cursive styles and ...

Dysgraphia
: A disorder involving difficulties with writing or typing, sometimes due to problems with
eye–hand coordination Hand-eye coordination (also known as eye-hand coordination) is the coordinated control of Eye movement (sensory), eye movement with hand movement and the Visual perception, processing of visual input to guide reaching and grasping along with the u ...
; it also can impede direction- or sequence-oriented processes, such as tying knots or carrying out repetitive tasks. In dyslexia, dysgraphia is often multifactorial, due to impaired letter-writing
automaticity Automaticity is the ability to do things without occupying the mind with the low-level details required, allowing it to become an automatic response pattern or habit (psychology), habit. It is usually the result of learning, repetition (learning), ...
, organizational and elaborative difficulties, and impaired visual word forming, which makes it more difficult to retrieve the visual picture of words required for spelling. *
Attention deficit hyperactivity disorder Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder Neurodevelopmental disorders are a group of disorders that affect the development of the nervous system, leading to abnormal brain function which may affect ...
(ADHD): A disorder characterized by problems sustaining attention, hyperactivity, or acting impulsively. Dyslexia and ADHD commonly occur together. Approximately 15% or 12–24% of people with dyslexia have ADHD; and up to 35% of people with ADHD have dyslexia. *
Auditory processing disorder Auditory processing disorder (APD), rarely known as King-Kopetzky syndrome or auditory disability with normal hearing (ADN), is an umbrella term for a variety of disorders that affect the way the brain processes auditory information. Individuals w ...
: A listening disorder that affects the ability to process auditory information. This can lead to problems with auditory memory and auditory
sequencing In genetics Genetics is a branch of biology concerned with the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) Though heredity had been observed for millennia, Gregor Mendel, Moravia, Moravian scientist ...

sequencing
. Many people with dyslexia have auditory processing problems, and may develop their own logographic cues to compensate for this type of deficit. Some research suggests that auditory processing skills could be the primary shortfall in dyslexia. *
Developmental coordination disorder Developmental coordination disorder (DCD), also known as developmental motor coordination disorder, developmental dyspraxia or simply dyspraxia, is a chronic neurological disorder A neurological disorder is any disorder of the nervous system ...
: A neurological condition characterized by difficulty in carrying out routine tasks involving balance, fine-
motor control Motor control is the regulation of movement in organisms In biology, an organism () is any organic, life, living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified ...
,
kinesthetic Proprioception ( ), also referred to as kinaesthesia (or kinesthesia), is the sense Sense relates to any of the systems and corresponding organs involved in sensation, i.e. the physical process of responding to Stimulus (physiology), stimuli and ...
coordination, difficulty in the use of speech sounds, problems with
short-term memory Short-term memory (or "primary" or "active memory") is the capacity for holding, but not manipulating, a small amount of information in mind The mind is the set of faculties responsible for mental Phenomenon, phenomena. Often the term is also ...
, and organization.


Causes

Researchers have been trying to find the neurobiological basis of dyslexia since the condition was first identified in 1881. For example, some have tried to associate the common problem among people with dyslexia of not being able to see letters clearly to abnormal development of their visual nerve cells.


Neuroanatomy

Neuroimaging Neuroimaging or brain imaging is the use of various techniques to either directly or indirectly Medical imaging, image the neuroanatomy, structure, function, or pharmacology of the nervous system. It is a relatively new discipline within medicine ...
techniques, such as
functional magnetic resonance imaging Functional magnetic resonance imaging or functional MRI (fMRI) measures brain activity by detecting changes associated with . This technique relies on the fact that cerebral blood flow and neuronal activation are coupled. When an area of the brai ...

functional magnetic resonance imaging
(
fMRI Functional magnetic resonance imaging or functional MRI (fMRI) measures brain activity by detecting changes associated with blood flow Hemodynamics American and British English spelling differences#ae and oe, or haemodynamics are the Fluid dynami ...

fMRI
) and
positron emission tomography Positron emission tomography (PET) is a functional imaging technique that uses radioactive substances known as radiotracers to visualize and measure changes in Metabolism, metabolic processes, and in other physiological activities including blo ...
(PET), have shown a correlation between both functional and structural differences in the brains of children with reading difficulties. Some people with dyslexia show less electrical activation in parts of the left hemisphere of the brain involved with reading, such as the
inferior frontal gyrus The inferior frontal gyrus (IFG), (gyrus frontalis inferior), is the lowest positioned gyrus of the frontal gyri, of the frontal lobe, and is part of the prefrontal cortex. Its superior border is the inferior frontal sulcus (which divides it from ...

inferior frontal gyrus
,
inferior parietal lobule The inferior parietal lobule (subparietal district) lies below the horizontal portion of the intraparietal sulcus, and behind the lower part of the postcentral sulcus. Also known as Geschwind’s territory after Norman Geschwind, an American ne ...
, and the middle and . Over the past decade, brain activation studies using PET to study language have produced a breakthrough in the understanding of the neural basis of language. Neural bases for the visual
lexicon A lexicon is the vocabulary A vocabulary is a set of familiar words In linguistics, a word of a spoken language can be defined as the smallest sequence of phonemes that can be uttered in isolation with semantic, objective or pragmatics, pra ...

lexicon
and for auditory verbal
short-term memory Short-term memory (or "primary" or "active memory") is the capacity for holding, but not manipulating, a small amount of information in mind The mind is the set of faculties responsible for mental Phenomenon, phenomena. Often the term is also ...
components have been proposed, with some implication that the observed neural manifestation of developmental dyslexia is task-specific (i.e., functional rather than structural). fMRIs of people with dyslexia indicate an interactive role of the
cerebellum The cerebellum (Latin for "little brain") is a major feature of the hindbrain The hindbrain or rhombencephalon is a developmental Development of the human body is the process of growth to maturity. The process begins with fertilization ...

cerebellum
and cerebral cortex as well as other brain structures in reading. The cerebellar theory of dyslexia proposes that impairment of cerebellum-controlled muscle movement affects the formation of words by the tongue and facial muscles, resulting in the
fluency Fluency (also called volubility and eloquency) is the property of a person A person (plural people or persons) is a being that has certain capacities or attributes such as reason Reason is the capacity of consciously applying logic Logic ...
problems that some people with dyslexia experience. The cerebellum is also involved in the of some tasks, such as reading. The fact that some children with dyslexia have motor task and balance impairments could be consistent with a cerebellar role in their reading difficulties. However, the cerebellar theory has not been supported by controlled research studies.


Genetics

Research into potential genetic causes of dyslexia has its roots in post-autopsy examination of the brains of people with dyslexia. Observed anatomical differences in the
language center In neuroscience and psychology, the term language center refers collectively to the areas of the brain which serve a particular function for speech processing and Speech production, production. Language is a core system, which gives humans the capa ...

language center
s of such brains include microscopic
cortical Cortex or cortical may refer to: Science Anatomy * Cortex (anatomy), the outermost or superficial layer of an organ * Cortex (hair), the middle layer of a strand of hair * Adrenal cortex, the portion of the adrenal gland that produces cortisol and ...
malformations known as ectopias, and more rarely,
vascular The blood vessels are the components of the circulatory system The circulatory system, also called the cardiovascular system or the vascular system, is an Biological system, organ system that permits blood to circulate and transport nutrien ...
micro-malformations, and
microgyrus A microgyrus is an area of the cerebral cortex that includes only four cortical layers instead of six. Microgyria are believed by some to be part of the genetic lack of prenatal development which is a cause of, or one of the causes of, dyslexia. ...
—a smaller than usual size for the gyrus. The previously cited studies and others suggest that abnormal cortical development, presumed to occur before or during the sixth month of
fetal A fetus or foetus (; plural fetuses, feti, foetuses, or foeti) is the unborn offspring that develops from an animal embryo An embryo is the early stage of development of a multicellular organism A multicellular organism is an organism tha ...

fetal
brain development, may have caused the abnormalities. Abnormal cell formations in people with dyslexia have also been reported in non-language cerebral and subcortical brain structures. Several genes have been associated with dyslexia, including DCDC2 and KIAA0319 on
chromosome 6 Chromosome 6 is one of the 23 pairs of chromosome A chromosome is a long DNA molecule with part or all of the genome, genetic material of an organism. Most eukaryotic chromosomes include packaging proteins called histones which, aided by ...

chromosome 6
, and DYX1C1 on
chromosome 15 Chromosome 15 is one of the 23 pairs of chromosome A chromosome is a long DNA molecule with part or all of the genetic material of an organism. Most eukaryotic chromosomes include packaging proteins called histones which, aided by chape ...
.


Gene–environment interaction

The contribution of gene–environment interaction to reading disability has been intensely studied using
twin studies Twin studies are studies conducted on identical or fraternal twins. They aim to reveal the importance of environmental and genetic influences for traits, phenotype In genetics Genetics is a branch of biology Biology is the ...
, which estimate the proportion of variance associated with a person's environment and the proportion associated with their genes. Both environmental and genetic factors appear to contribute to reading development. Studies examining the influence of environmental factors such as parental education and teaching quality have determined that genetics have greater influence in supportive, rather than less optimal, environments. However, more optimal conditions may just allow those genetic risk factors to account for more of the variance in outcome because the environmental risk factors have been minimized. As environment plays a large role in learning and memory, it is likely that
epigenetic In biology, epigenetics is the study of heritability, heritable phenotype changes that do not involve alterations in the DNA sequence. The Ancient Greek, Greek prefix ''wikt:epi-, epi-'' ( "over, outside of, around") in ''epigenetics'' implies f ...
modifications play an important role in reading ability. Measures of
gene expression Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product that enables it to produce end products, protein or non-coding RNA, and ultimately affect a phenotype, as the final effect. The ...

gene expression
,
histone modifications Image:Nucleosome structure.png, 300px, Schematic representation of the assembly of the core histones into the nucleosome. In biology, histones are highly Base_(chemistry), basic proteins abundant in lysine and arginine residues that are found in euk ...
, and
methylation In the chemical sciences, methylation denotes the addition of a methyl group A methyl group is an alkyl derived from methane, containing one carbon atom chemical bond, bonded to three hydrogen atoms — CH3. In chemical formula, fo ...

methylation
in the human periphery are used to study epigenetic processes; however, all of these have limitations in the extrapolation of results for application to the human brain.


Language

The orthographic complexity of a language directly affects how difficult it is to learn to read it. Paulesu, Eraldo; Brunswick, Nicola and Paganelli, Federica (2010). "Cross-cultural differences in unimpaired and dyslexic reading: Behavioral and functional anatomical observations in readers of regular and irregular orthographies. Chapter 12 i
Reading and Dyslexia in Different Orthographies
. Eds. Nicola Brunswick, Siné McDougall, and Paul de Mornay Davies. Psychology Press.
English and French have comparatively "deep" phonemic orthographies within the
Latin alphabet The Latin alphabet or Roman alphabet is the collection of letters originally used by the ancient Romans In historiography Historiography is the study of the methods of historian ( 484– 425 BC) was a Greek historian who lived ...

Latin alphabet
writing system A writing system is a method of visually representing verbal communication Communication (from Latin Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communic ...
, with complex structures employing spelling patterns on several levels: letter-sound correspondence, syllables, and
morpheme A morpheme is the smallest meaningful lexical itemIn lexicography, a lexical item (or lexical unit / LU, lexical entry) is a single word, a part of a word, or a chain of words ( catena) that forms the basic elements of a language's lexicon A ...
s. Languages such as Spanish, Italian and Finnish primarily employ letter-sound correspondence—so-called "shallow" orthographies—which makes them easier to learn for people with dyslexia.
Logograph In a written language A written language is the representation of a spoken or gestural language by means of a writing system. Written language is an invention in that it must be taught to children, who will pick up spoken language or sign ...
ic writing systems, such as
Chinese characters Chinese characters, also called ''hanzi'' (), are logogram In a written language A written language is the representation of a spoken or gestural language A language is a structured system of communication used by humans, ...
, have extensive symbol use; and these also pose problems for dyslexic learners.


Pathophysiology

For most people who are right-hand dominant, the left hemisphere of their brain is more specialized for
language processing Language processing refers to the way humans use words to communicate ideas and feelings, and how such communications are processed and understood. Language processing is considered to be a uniquely human ability that is not produced with the same ...

language processing
. With regard to the mechanism of dyslexia, fMRI studies suggest that this specialization is less pronounced or absent in people with dyslexia. In other studies, dyslexia is correlated with anatomical differences in the
corpus callosum The corpus callosum (Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the Roman Repu ...

corpus callosum
, the bundle of nerve fibers that connects the left and right hemispheres. Data via diffusion tensor MRI indicate changes in connectivity or in gray matter density in areas related to reading and language. Finally, the left
inferior frontal gyrus The inferior frontal gyrus (IFG), (gyrus frontalis inferior), is the lowest positioned gyrus of the frontal gyri, of the frontal lobe, and is part of the prefrontal cortex. Its superior border is the inferior frontal sulcus (which divides it from ...

inferior frontal gyrus
has shown differences in phonological processing in people with dyslexia. Neurophysiological and imaging procedures are being used to ascertain phenotypic characteristics in people with dyslexia, thus identifying the effects of dyslexia-related genes.


Dual route theory

The dual-route theory of
reading Reading is the process of taking in the sense or meaning of letters, symbols, ''etc.'', especially by sight or touch. For educators and researchers, reading is a multifaceted process involving such areas as word recognition, orthography An ...
aloud was first described in the early 1970s. This theory suggests that two separate mental mechanisms, or cognitive routes, are involved in reading aloud. One mechanism is the lexical route, which is the process whereby skilled readers can recognize known words by sight alone, through a "dictionary" lookup procedure. The other mechanism is the nonlexical or sublexical route, which is the process whereby the reader can "sound out" a written word. This is done by identifying the word's constituent parts (letters,
phonemes In phonology Phonology is a branch of linguistics Linguistics is the scientific study of language, meaning that it is a comprehensive, systematic, objective, and precise study of language. Linguistics encompasses the analysis of ...

phonemes
,
graphemes In linguistics Linguistics is the science, scientific study of language. It encompasses the analysis of every aspect of language, as well as the methods for studying and modeling them. The traditional areas of linguistic analysis include ...
) and applying knowledge of how these parts are associated with each other, for example, how a string of neighboring letters sound together. The dual-route system could explain the different rates of dyslexia occurrence between different languages (e.g., the consistency of phonological rules in the Spanish language could account for the fact that Spanish-speaking children show a higher level of performance in non-word reading, when compared to English-speakers).


Diagnosis

Dyslexia is a heterogeneous, dimensional learning disorder that impairs accurate and fluent word reading and spelling. Typical—but not universal—features include difficulties with phonological awareness; inefficient and often inaccurate processing of sounds in oral language (''phonological processing''); and verbal working memory deficits.Snowling, Margaret J. ''Dyslexia: A Very Short Introduction''. Oxford University Press, 2019. Dyslexia is a
neurodevelopmental disorder Neurodevelopmental disorders are a group of disorders that affect the development of the nervous system, leading to abnormal brain function which may affect emotion Emotions are biological states associated with all of the nerve systems brou ...
, subcategorized in diagnostic guides as a ''learning disorder with impairment in reading'' (ICD-11 prefixes "developmental" to "learning disorder"; DSM-5 uses "specific"). Dyslexia is not a problem with
intelligence Intelligence has been defined in many ways: the capacity for abstraction Abstraction in its main sense is a conceptual process where general rules and concept Concepts are defined as abstract ideas or general notions that occur in the mind, ...
. Emotional problems often arise secondary to learning difficulties. The
National Institute of Neurological Disorders and Stroke The National Institute of Neurological Disorders and Stroke (NINDS) is a part of the U.S. National Institutes of Health The National Institutes of Health (NIH) () is the primary agency of the United States government responsible for biomedical ...

National Institute of Neurological Disorders and Stroke
describes dyslexia as "difficulty with phonological processing (the manipulation of sounds), spelling, and/or rapid visual-verbal responding". The British Dyslexia Association defines dyslexia as "a learning difficulty that primarily affects the skills involved in accurate and fluent word reading and spelling" and is characterized by "difficulties in phonological awareness, verbal memory and verbal processing speed". ''Phonological awareness'' enables one to identify, discriminate, remember (
working memory Working memory is a cognitive system with a limited capacity that can hold information temporarily. Working memory is important for reasoning and the guidance of decision-making and behavior. Working memory is often used synonymously with short-te ...
), and mentally manipulate the sound structures of language—
phonemes In phonology Phonology is a branch of linguistics Linguistics is the scientific study of language, meaning that it is a comprehensive, systematic, objective, and precise study of language. Linguistics encompasses the analysis of ...

phonemes
, onsite-rime segments, syllables, and words.


Assessment

* Strive for a multidisciplinary team approach involving the child's parent(s) and teacher(s); school psychologist; pediatrician; and, as appropriate, speech and language pathologist (speech therapist); and
occupational therapist Occupational Therapists (OTs) are health care professionals specializing in occupational therapy Occupational therapy (OT) is a profession within healthcare Health care, health-care, or healthcare is the maintenance or improvement of health ...
. * Possess a thorough familiarity with typical ages children reach various general developmental milestones (write first name; draw a square), and domain-specific milestones, such as phonological awareness (recognize rhyming words; identify the initial sounds in words). * Avoid over-reliance on tests. Careful observation of the child in the school and home environments, and sensitive, comprehensive parental interviews are just as important as tests. * Take advantage of the empirically supported "response to intervention" (RTI) approach, which "... involves monitoring the progress of a group of children through a programme of intervention rather than undertaking a static assessment of their current skills. Children with the most need are those who fail to respond to effective teaching, and they are readily identified using this approach."


Assessment tests

There is a wide range of tests that are used in clinical and educational settings to evaluate the possibility that a person might have dyslexia. If initial testing suggests that a person might have dyslexia, such tests are often followed up with a full diagnostic assessment to determine the extent and nature of the disorder. Some tests can be administered by a teacher or computer; others require specialized training and are given by psychologists. Some test results indicate how to carry out teaching strategies. Because a variety of different cognitive, behavioral, emotional, and environmental factors all could contribute to difficultly learning to read, a comprehensive evaluation should consider these different possibilities. These tests and observations can include: * General measures of cognitive ability, such as the
Wechsler Intelligence Scale for Children The Wechsler Intelligence Scale for Children (WISC) is an individually administered intelligence test for children between the ages of 6 and 16. The Fifth Edition (WISC-V; Wechsler, 2014) is the most recent version. The WISC-V takes 45 to 65 minu ...
, Woodcock-Johnson Tests of Cognitive Abilities, or Stanford-Binet Intelligence Scales. Low general cognitive ability would make reading more difficult. Cognitive ability measures also often try to measure different cognitive processes, such as verbal ability, nonverbal and spatial reasoning, working memory, and processing speed. There are different versions of these tests for different age groups. Almost all of these require additional training to give and score correctly, and are done by psychologists. According to Mather and Schneider (2015), a confirmatory profile and/or pattern of scores on cognitive tests confirming or ruling-out reading disorder has not yet been identified. * Screening or evaluation for mental health conditions: Parents and teachers can complete rating scales or behavior checklists to gather information about emotional and behavioral functioning for younger people. Many checklists have similar versions for parents, teachers, and younger people old enough to read reasonably well (often 11 years and older) to complete. Examples include the Behavioral Assessment System for Children, and the Strengths and Difficulties Questionnaire. All of these have nationally representative norms, making it possible to compare the level of symptoms to what would be typical for the younger person's age and biological sex. Other checklists link more specifically to psychiatric diagnoses, such as the Vanderbilt ADHD Rating Scales or the Screen for Child Anxiety Related Emotional Disorders (SCARED). Screening uses brief tools that are designed to catch cases with a disorder, but they often get false positive scores for people who do not have the disorder. Screeners should be followed up by a more accurate test or diagnostic interview as a result. Depressive disorders and anxiety disorders are two-three times higher in people with dyslexia, and attention-deficit/hyperactivity disorder is more common, as well. * Review of academic achievement and skills: Average spelling/reading ability for a dyslexic is a percentage ranking <16, well below normal. In addition to reviewing grades and teacher notes, standardized test results are helpful in evaluating progress. These include group administered tests, such as the
Iowa Tests of Educational DevelopmentThe Iowa Tests of Educational Development (ITED) are a set of standardized tests given annually to Secondary education in the United States, high school students in many schools in the United States, covering Grades 9 to 12. The tests were created by ...
, that a teacher may give to a group or whole classroom of younger people at the same time. They also could include individually administered tests of achievement, such as the Wide Range Achievement Test, or the Woodcock-Johnson (which also includes a set of achievement tests). The individually administered tests again require more specialized training.


Screening

Screening procedures seek to identify children who show signs of possible dyslexia. In the preschool years, a family history of dyslexia, particularly in biological parents and siblings, predicts an eventual dyslexia diagnosis better than any test. In primary school (ages 5–7), the ideal screening procedure consist of training primary school teachers to carefully observe and record their pupils' progress through the phonics curriculum, and thereby identify children progressing slowly. When teachers identify such students they can supplement their observations with screening tests such as the ''Phonics screening check'' used by United Kingdom schools during
Year one The term "Year One" in political history usually refers to the institution of radical, revolutionary change. This usage dates from the time of the French Revolution The French Revolution ( ) refers to the period that began with the Estat ...
. In the medical setting, child and adolescent psychiatrist M. S. Thambirajah emphasizes that " ven the high prevalence of developmental disorders in school-aged children, all children seen in clinics should be systematically screened for developmental disorders irrespective of the presenting problem/s." Thambirajah recommends screening for developmental disorders, including dyslexia, by conducting a brief developmental history, a preliminary psychosocial developmental examination, and obtaining a school report regarding academic and social functioning.


Management

Through the use of compensation strategies, therapy and educational support, individuals with dyslexia can learn to read and write. There are techniques and technical aids that help to manage or conceal symptoms of the disorder. Reducing stress and anxiety can sometimes improve written comprehension. For
dyslexia intervention Management of dyslexia depends on a multiple of variables; there is no one specific strategy or set of strategies which will work for all who have dyslexia. Some teaching is geared to specific reading skill areas, such as phonetic decoding; wher ...
with alphabet-writing systems, the fundamental aim is to increase a child's awareness of correspondences between
grapheme In linguistics Linguistics is the scientific study of language A language is a structured system of communication used by humans, including speech (spoken language), gestures (Signed language, sign language) and writing. Most langu ...

grapheme
s (letters) and
phoneme In phonology and linguistics, a phoneme is a unit of sound that distinguishes one word from another in a particular language. For example, in most List of dialects of English, dialects of English, with the notable exception of the West Midlan ...
s (sounds), and to relate these to reading and spelling by teaching how sounds blend into words. Reinforced collateral training focused on reading and spelling may yield longer-lasting gains than oral phonological training alone. Early intervention can be successful in reducing reading failure. Research does not suggest that specially-tailored fonts (such as Dyslexie and ) help with reading. Children with dyslexia read text set in a regular font such as
Times New Roman Times New Roman is a serif In , a serif () is a small line or stroke regularly attached to the end of a larger stroke in a letter or symbol within a particular or family of fonts. A or "font family" making use of serifs is called a serif ty ...

Times New Roman
and
Arial Arial, sometimes marketed or displayed in software as Arial MT, is a sans-serif In typography Typography is the art and technique of arranging type to make written language A written language is the representation of a spoken ...

Arial
just as quickly, and they show a preference for regular fonts over specially-tailored fonts. Some research has pointed to increased
letter-spacing Examples of headline letter spacing In typography Typography is the art and technique of arranging type to make written language A written language is the representation of a spoken or gestural language A language is a structu ...
being beneficial. There is currently no evidence showing that music education significantly improves the reading skills of adolescents with dyslexia.


Prognosis

Dyslexic children require special instruction for word analysis and spelling from an early age. The prognosis, generally speaking, is positive for individuals who are identified in childhood and receive support from friends and family. The New York educational system (NYED) indicates "a daily uninterrupted 90-minute block of instruction in reading", furthermore "instruction in phonemic awareness, phonics, vocabulary development, reading fluency" so as to improve the individual's reading ability.


Epidemiology

The percentage of people with dyslexia is unknown, but it has been estimated to be as low as 5% and as high as 17% of the population. While it is diagnosed more often in males, some believe that it affects males and females equally. There are different definitions of dyslexia used throughout the world, but despite significant differences in writing systems, dyslexia occurs in different populations. Dyslexia is not limited to difficulty in converting letters to sounds, and Chinese people with dyslexia may have difficulty converting
Chinese character Chinese characters, also called ''hanzi'' (), are logogram In a written language A written language is the representation of a spoken or gestural language A language is a structured system of communication used by humans, ...

Chinese character
s into their meanings. The Chinese vocabulary uses logographic, monographic, non-alphabet writing where one character can represent an individual phoneme. The phonological-processing hypothesis attempts to explain why dyslexia occurs in a wide variety of languages. Furthermore, the relationship between phonological capacity and reading appears to be influenced by orthography.


History

Dyslexia was clinically described by Oswald Berkhan in 1881, but the term ''dyslexia'' was coined in 1883 by Rudolf Berlin, an ophthalmologist in Stuttgart.Berlin, Rudolf. [No title.] ''Medicinisches Correspondenzblatt des Württembergischen Ärztlichen Landesvereins'' [Correspondence Sheet of the Württemberg Medical Association] 53 (1883): 209.Webster's Third New International Dictionary. "History and Etymology for dyslexia", s.v. "mwod:dyslexia, dyslexia, noun". Springfield, MA: Merriam-Webster, 1961, rev. 2016. He used the term to refer to the case of a young boy who had severe difficulty learning to read and write, despite showing typical intelligence and physical abilities in all other respects. In 1896, W. Pringle Morgan, a British physician from Seaford, East Sussex, published a description of a reading-specific learning disorder in a report to the ''British Medical Journal'' titled "Congenital Word Blindness". The distinction between phonological versus surface types of dyslexia is only descriptive, and without any etiological assumption as to the underlying brain mechanisms. However, studies have alluded to potential differences due to variation in performance.


Society and culture

As is the case with any disorder, society often makes an assessment based on incomplete information. Before the 1980s, dyslexia was thought to be a consequence of education, rather than a neurological disability. As a result, society often misjudges those with the disorder. There is also sometimes a workplace stigma and negative attitude towards those with dyslexia. If the instructors of a person with dyslexia lack the necessary training to support a child with the condition, there is often a negative effect on the student's learning participation. Since at least the 1960s in the UK, the children diagnosed with developmental dyslexia have consistently been from privileged families. Although half of prisoners in the UK have significant reading difficulties, very few have ever been evaluated for dyslexia. Access to some special educational resources and funding is contingent upon having a diagnosis of dyslexia. As a result, when Staffordshire and Warwickshire proposed in 2018 to teach reading to all children with reading difficulties, using techniques proven to be successful for most children with a diagnosis of dyslexia, without first requiring the families to obtain an official diagnosis, dyslexia advocates and parents of children with dyslexia were fearful that they were losing a privileged status.


Research

Most dyslexia research relates to alphabetic writing systems, and especially to European languages. However, substantial research is also available regarding people with dyslexia who speak Arabic, Chinese, Hebrew, or other languages. The outward expression of individuals, with reading disability and regular poor readers is the same in some respects.


See also

* Dyscalculia, difficulty comprehending numbers and math * Learning to read * Orton-Gillingham


References


Further reading

* * * * * * * * * * * * * * * * * *


External links

{{Authority control Dyslexia, Educational psychology Literacy Learning to read Specific developmental disorders Reading (process), *Dyslexia Wikipedia medicine articles ready to translate Wikipedia neurology articles ready to translate Special education Writing