Reading Learning Disorder 

Updated: May 27, 2016
Author: Eric R Crouch, MD; Chief Editor: Caroly Pataki, MD 

Overview

Background

Learning disabilities, which include reading disabilities, are frequently diagnosed in children. Learning disabilities can occur for a variety of reasons and often require a multidisciplinary approach to address some of the more complex problems that can surround the diagnosis. Early diagnosis and referral to qualified educational professionals for evidence-based assessments and therapies offers the best chance for an improvement in quality of life. Learning disabilities are primarily language-based disorders; vision problems do not cause primary dyslexia or learning disabilities. Although there are some vision problems that can interfere with the development of vision, the neurodevelopmental issues surrounding learning disabilities generally involve other areas of neural processing. 

Diagnostic Criteria (DSM5)

In 2013, the American Psychiatric Association released the Fifth Edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM5). In this latest edition, specific learning disorder (SLD) is the umbrella term for mathematics, reading, and written expression disorders. It is now a single, overall diagnosis, incorporating deficits that impact academic achievement. Rather than limiting learning disorders to diagnoses particular to reading, mathematics and written expression, the criteria describe shortcomings in general academic skills and provide detailed specifiers for the areas of reading, mathematics, and written expression. The diagnosis requires persistent difficulties in reading, writing, arithmetic, or mathematical reasoning skills during formal years of schooling.[1]

Specific learning disorder with impairment in reading includes possible deficits in:

  • Word reading accuracy
  • Reading rate or fluency
  • Reading comprehension

Impediments to successful reading may be caused by one or more impairments to the 3 skills necessary for reading: (1) word decoding, as in dyslexia; (2) automaticity of letter and word recognition, but intact decoding of words, as in a reading fluency problem; and (3) understanding the meaning of words, when decoding and fluency function well, as in a reading comprehension disorder.

Dyslexia is an alternative term used to refer to a pattern of learning difficulties characterized by problems with accurate or fluent word recognition, poor decoding, and poor spelling abilities.

Dyslexia is traditionally defined as an unexpected difficulty learning to read despite adequate intelligence, motivation, and educational opportunities. Longitudinal studies have demonstrated an association between dyslexia and language delays. Children may also have developmental problems with either expressive language, receptive language, or both. Such children are more likely to developing reading disorders. Many children with difficulties with reading, expressive language, or receptive language can also develop behavior disturbances in the home or classroom. These behaviors may ultimately impact their psychosocial development.

Pathophysiology

The precise mechanism by which dyslexia develops has not been completely elucidated and numerous theories have been advanced.

Visual perceptual problems

At the beginning of the 20th century, dyslexia was believed to be caused by defects in the visual processing system that reversed and transposed words and letters. This belief persists despite research over the past 30 years that shows children with dyslexia do not have an increased risk of poorer vision than the general population. Attempts to overcome these visual defects through various eye training exercises to improve visual perception of written letters and words has not proven effective in treating dyslexia, dyspraxia, or dyscalculia problems.[2]

The etiology of reading disorders has been shown to involve disruption of phonemic processing. Thus, ocular movements are generally not a contributing factor in dyslexic patients. Even with occlusion, dyslexia persists on testing and most dyslexic patients do not demonstrate impaired oculomotor control. Weak ocular dominance by synoptophore testing has been studied by Stein et al; however, ocular dominance therapy has not proved to be an effective treatment in resolving dyslexia.[3]  Although saccades can be altered in patients with dyslexia, patterns of eye movement are a symptom rather than a distinct cause of dyslexia.[4]  Improved reading can result in improved saccadic eye movements, but therapies directed at improving saccadic eye movements have not shown improvement in reading scores.[5]

The visual system involves cortical function in the occipital and subsequently occipito-parietal and occipito-temporal lobes. The process for deciphering of visual images begins in the retina, is transmitted via the optic nerve, and is ultimately processed in the brain. The processes of visual sequencing, visual perception, and memory do not cause dyslexia.

Phonetic processing

Communication of thought is the goal of all language skills. Psychological, educational, and brain research over the past 20 years has consistently shown that dyslexia is a deficit of language processing. Dyslexia involves deficient decoding of individual linguistic units, called phonemes, which are the smallest detectable sound in a spoken word. Poor abilities in any part of this process (eg, segmenting/blending, speed, memory) adversely affects overall reading ability. A child with dyslexia typically has problems with segmentation, the process of recognizing different phonemes that constitute words or with blending these sounds to make words. A problem with speed or with rapidly naming words or letters interrupts reading fluency. Additionally, visual sequential memory problems interfere with reading comprehension.

Phonemes are the building blocks of the linguistic system and critical to developing spoken language. Phonological processing areas in the brain must break words into phonemic units before an individual can identify, understand, store, or remember them. Phonemic processing occurs automatically, without the speaker or listener consciously processing the information. Speech requires blending the phonemes into complete words, and thus words are heard as seamless, with no breaks. Although the word cat may seem like a single sound, humans can segment it into the 3 component phonemes.

A morpheme is the smallest meaningful speech sounds. Phonemes and morphemes are the fundamental elements of the linguistic system and critical to developing spoken and written language. Graphemes, the smallest unit in written language, contain visual symbols to represent the spoken phoneme. Individuals with dyslexia evidence impaired phonological awareness and as a result cannot adequately pair the visually processed graphemes with their associated phonemes.[6]

Research has shown that reading directly reflects spoken language. The process of reading involves the perception of alphabetic script coded as phonemes (ie, each symbol represents a phoneme). A person must recognize the visual sequence of letters in a specific order and correlate with the proper phonology. An individual must be able to simultaneously segment the letters into sounds and then blend those sounds into words.

This process of associating a grapheme with its phoneme must occur fast enough for reading fluency, and the reader must also remember and retain the words read long enough to recall their meanings. Slow grapheme-phoneme processing appears to be the primary cause of dyslexic reading problems.

The most prominent current hypothesis regarding the neuroanatomic regions of phonological and visual processing is that atypical phonological processing in the prereading years leads to inefficient mapping during the development of reading. Thus, the atypical phonological processing disrupts the development of the functional specialization of the visual areas. The brains of individuals with reading disorders are organized somewhat differently and appear to process the phonological information in a less efficient, more diffuse manner.

Neurophysiology

Neuroimaging has demonstrated variations in the right temporoparietal-occipital region among patients with dyslexia. The specific asymmetries have been located in the angular gyrus and corpus callosum. The angular gyrus is located in parietal lobe, specifically Brodmann’s area 39, and is involved in language, cognition, and mathematics. This may, in part, explain the association between dyslexia and dyscalculia.

Postmortem studies have documented disorganized neuronal migration involving other areas, such as the thalamus, subcortical white matter, and parieto-occipital region. EEG studies have also demonstrated differences between patients with and without dyslexia. Neurologically, positron emission tomography (PET) scan studies suggest that phonological defects in reading strongly relate to decreased activity in the left perisylvian region, including the superior and medial temporal gyri. Additional functional imaging work indicates that anterior regions of the brain are activated during phonological or rhyming tasks.

In addition, the left temporo-occipital region, which is active during the automatic perception and processing of visually presented words in skilled readers, is also implicated in reading problems. A lack of word-specific responsiveness in this region is found in adults with reading impairment. Anatomical lesion analysis has shown that this region is necessary for rapid perception of word forms.

Genetics

Genetic and neurobiological research confirms psychological research in this area. Family studies show that a reading disorder is heritable, is found in clusters in families, and probably reflects autosomal dominant transmission. Research has shown a high familial incidence of dyslexia and concordance among both monozygotic and dizygotic twins. Thus far, research has identified 8 isolated genetic defects among dyslexic patients, and at least another 20 genetic conditions with normal intelligence levels but associated reading disabilities with dyslexic features.

Challenges to the existing paradigm view dyslexia as largely determined by genetic load with the additional perspective that expression of the phenotype is on a continuum with the disability on one end and intact reading skills on the other. Given increasing evidence that environment can modify expression of phenotype, the possibility is being explored that the genetic diathesis could be manipulated by enrichment experience to express the nonpathologic aspect of the dyslexia phenotype.[7]

Epidemiology

Frequency

United States

The prevalence of specific learning disoder across the academic domains of reading, writing, and mathematics is 5%-15% among school-age children across different languages and cultures.[1] Children with delays can be diagnosed with attention deficit disorders, brain dysfunction, sensory integration issues, dyslexia, dyspraxia, and dyscalculia. On occasion, a child may have more than one condition present. Dyslexia accounts for the majority of learning disabilities.[8]   

Data from epidemiological studies indicate as many as 40% of all early elementary school students in the United States have some initial difficulty learning to read; however, many of these children ultimately develop normal reading proficiency. Among older elementary students, up to 15-20% of children have significant problems and demonstrate difficulty with reading fluency, comprehension, and spelling.[9] Developmental delays, emotional disturbance, inadequate education, and sensory disabilities can also lead to academic failures and delays and should be investigated.

Reading disorder rates show no racial differences. For approximately the past 30 years, public schools have included the intelligence quotient (IQ) as part of their assessment for severe reading problems. A learning disability has been defined as a significant discrepancy between a child's IQ and reading achievement score. For example, if a child has an IQ in the 50th percentile and a reading score in the 20th percentile, that child would be considered to have a reading discrepancy. Care should be taken with children with below-average IQ scores and poor reading performance, as such children can be misdiagnosed as reading disabled or delayed.

However, the 2004 version of the federal Individuals with Disabilities Education Act (IDEA) no longer requires states to use the discrepancy score criteria (eg, if the IQ is 20 points higher than the reading achievement score, the discrepancy is significant) to identify reading disabilities. All that is now required to identify a learning disability is a significant delay and a poor response to a reading intervention. How each state interprets this law in the public school is still being developed. Because states develop their own rules, some states may retain the discrepancy criteria.

Sex

Boys are 1.5 times more likely to be referred for reading problems. Although epidemiological studies in the past demonstrated roughly equal reading scores for girls and boys, more recent studies have demonstrated a wider variance in reading performance among male students.[10]

Language

Dyslexia can occur in any language. There have even been cases of differential dyslexia in which a child can be more dyslexic in one language than another. Dyslexia may be more prevalent in English-speaking countries.

Prognosis

Children with learning disabilities can achieve academic success through a multidisciplinary approach that targets and manages the complex aspects associated with the condition. Children with learning disabilities can be challenging, and addressing the issues is not always simple. With appropriate accommodations and support, children with learning disabilities can achieve academic progress. Patient advocacy is important to ensuring the child's issues are appropriately addressed through an individualized educational plan (IEP).

Patient Education

Children with concerns for learning disabilities, such as dyslexia, dyscalculia, and dyspraxia, should be referred for multi-disciplinary evaluation with emphasis on educational, psychological, neurodevelopmental pediatrics, and medical assessments.

Broad-based support in the school and home including individualized care and evidence-based therapies should be utilized in maximizing children's neurodevelopment. These interventions can be combined with neuropsychological and medical treatments as needed.

Children with learning disabiliites who are thought to have poor visual development or oculomotor control should be referred to an ophthalmologist with experience with pediatric patients. Routine vision screening assessments will not necessarily detect learning disabilties since vision problems are not a primary cause of dyslexia.

Primary care physicians should help coordinate the multidisciplinary approach and refer children for evidence-based treatments.

Educators should make accommodations for patients with learning disablities and assist them in receiving individualized support in their school systems.

 

 

Presentation

History

Delayed early language development, difficulty segmenting words or recognizing the differences between similar sounds, and a family history of reading disability all indicate a potential learning problem. Reading disorders also correlate highly with attention deficit hyperactivity disorder (ADHD); accordingly, all children with ADHD should be screened for reading problems.[11]

Physical

Specific learning disorders are often not detected until school age. The evaluation may include ADHD testing, developmental evaluation, hearing and vision screenings, and child may ultimately be delayed in the diagnosis of a learning disorders. A multidisciplinary approach is often best in discerning the correct diagnosis and treatment plan.

The pediatrician, child psychiatrist, ophthalmologist, neurologist, psychologist, and developmental pediatrician all play important roles in the diagnosis of children with learning disabilities. Ideally, the clinicians are familiar with various metabolic and genetic syndromes because these conditions can often present with developmental delays and learning difficulties in school.

The pediatrician is best suited to oversee the management of other consultants and correlating the clinical findings. The pediatric psychiatrist is capable of performing a detailed series of tests to evaluating specific reading and learning disorders. The assessment also involves measuring the overall intelligence, reading accuracy, and comprehension. Mood and behavioral disorders are ruled out. The developmental pediatrician can assess spelling age, mathematical age, and visual and auditory perception. Specific testing, such as WISC and GORT testing, can be useful in comparing the child with age-matched peers. Both verbal and performance scales should be assessed to determine spatial organization, visual perception, and associative learning skills.

The pediatric ophthalmologist can assess the visual acuity, visual fields, ocular alignment, convergence and accommodative amplitudes, and sensorimotor evaluation of stereopsis and fusion. If age appropriate, color vision should also be assessed to alert parents and teachers of achromatopsia. Additionally, organic ocular disease, such as amblyopia, opacities of the visual axis, and retinopathies and optic neuropathies can be ruled out by the pediatric ophthalmologist. Refractive errors, if medically indicated, can be corrected with glasses. If fusional disease is present, cortical fusion disorders and motor fusion disorders can be addressed by the pediatric ophthalmologist. If age appropriate, convergence insufficiency should be ruled out.

The pediatric neurologist can assess gross motor skills, deep tendon reflexes, and diseases impacting cerebellar or extrapyramidal pathways.

Causes

Disrupted development of the neuroanatomic regions associated with phonemic segmentation are the primary etiology of reading disorders. Ocular movements and ocular dominance generally do not play any significant role in the development of dyslexia. Patients with dyslexia can demonstrate word reversals, substitutions, and skipping words. These symptoms have been shown to be based in deficiencies within the linguistic centers rather than visual processing disorders.[5]  Currently, there is insufficient and conflicting evidence regarding a disruption in the magnocelluluar visual system causing learning disabilities.

Dyslexia involves a difficulty for the child in the areas of reading, writing, and spelling. The learning disability disorders primarily involve problems in phonological skills and word decoding skills. The development of phonological skills ideally occurs in concert with the development of reading skills. However, there are different types of phonological skills and these particular skills are different relative weighting across different languages. A child with dyslexia may learn some phonological skills but remain lacking in others. These skills are then combined with writing (orthographic system). Memory of these two complementary systems of phonological skils and written skills must then be correctly practiced and reproduced. A disruption within this sequence of events is a prinicipal source of the learning disabilities demonstrated. Language development in the oral form plays a critical role in the language development of the written form. Reading and writing require more active learning than speaking alone does. In the process of reading and writing, children must decipher the alphabetic structure, acquire the correct corresponding symbolism, and determine the appropriate meaning. Many patients with dyslexia have a problem with the processing of the sound structure of the language. This is called a phonemic deficit.[12]  In more advanced cases, children may also exhibit a second deficit with specific letters, numbers, symbols, or pictures. As such, the child can appear to have or may actually have problems with attention and memory. This can sometimes lead to misdiagnosis of other conditions, such as ADHD. Alternatively, other co-existing diagnoses may result in providers and educators overlooking cases of concomitant dyslexia.

 

DDx

Diagnostic Considerations

Developmental delays can occur in various genetic syndromes. Genetics conditions, such as Sotos, tuberous sclerosis, neurofibromatosis, should be ruled out. The coarse features and corneal clouding of mucopolysaccharidoses should also be excluded as poor academic performance can be associated with developmental delays. Metabolic conditions should also be considered, such as hypothyroidism and diabetes. Agenesis of the corpus callosum, optic nerve hypoplasia, and septo-optic dysplasia should be ruled out as part of multi-disciplinary evaluation. The pediatric neurologist can determine if ventriculomegaly or neurodegenerative disorders are present.

Convergence insufficiency disorders should be ruled out in the evaluation of a child with poor or delayed reading and prescribed orthoptic treatment as initial treatment of any convergence insufficiency.

 

Workup

Other Tests

Children with normal reading processes spontaneously begin to decode and segment words at age 4-6 years. The most reliable indicator of a reading difficulty is the inability to decode single words. The 3 components of phonological processing that predict reading ability are (1) awareness of different phonemes (eg, ability to follow instructions such as pronouncing cup without the /k/ sound), (2) ability to name objects, letters, or numbers quickly, and (3) working memory (ie, ability to accurately repeat sentences, words, or strings of numbers). Although assessment of intellectual ability, IQ, and achievement level is included in a standard school assessment of reading, these data are unreliable predictors of overall reading ability. Phonological processing ability is the best predictor of reading.

In most public schools, an educational diagnostician, an educator trained as a reading specialist, and a school psychologist are the professionals charged with evaluation. Outside public schools, a child psychologist, an educational diagnostic specialist, or a child neuropsychologist is usually best able to examine a child with a reading disability.

Under the 2004 IDEA, greater emphasis is placed on "response to intervention" than is placed on testing. Thus, most schools now initially provide a more intense level of instruction when a child in kindergarten or first grade falls behind in reading. If the child does not respond to this intervention, formal testing is performed. However, under the 2004 IDEA, the parent may request (in writing) testing at any time, and the school must comply within the specific state rules and time frame. In other words, parents can insist on testing.

 

Treatment

Medical Care

Appropriate referrals to a special education (SPED) setting, specialized tutoring setting, or both can prove important for long-term progress and improved reading performance. Once the learning disorder of dyslexia or dyscalculia have been recognized and delineated, various methods of treatment should be used to assist the child's academic development. Remedial teachers, speech and language therapists, and occupational therapists can all be very valuable in the management of children with learning disorders and may also further refine the spectrum of clinical findings for the pediatrician. Remedial help has been found to have some benefit for dyslexic children, although the research is not universally supportive.

Various treatments regarding ocular dominance, eye teaming, and scotopic sensitivity have been applied to children with reading disorders. Evidence-based clinical research over the past 30 years has determined many of these alternative treatments to be ineffective. The physiological basis of dyslexia is not materially impacted by treatments that do not address the underlying neuroanatomic dysfunction in the phonemic processing.

The pediatric ophthalmologist and pediatric neurologist must explain to the parents that dyslexia is not a disorder of the visual system but rather is a disability in processing separate from the visual pathways to the occipital cortex and is based in neurophysiological maldevelopment of various regions of language development. Visual training, including eye muscle exercises, ocular pursuits, and training with or without bifocals does not benefit children with dyslexia, dyscalculia, or other learning disorders. Tinted lenses or Irlen lenses have also been unhelpful for children with dyslexia.

Balance board training, crawling exercises, and perceptual training have also been ineffective for children with dyslexia and other learning disorders. Some of these controversial methods can even result in delayed diagnosis or delayed treatment for the affected child.

Children with a concomitant diagnosis of ADHD or hyperactivity may benefit from pharmaceutical treatment. However, the parents should be cautioned to realize that such treatments, although they may improve behavior and attention, are not directly associated with improvements in academic performance. The child still requires specific treatments tailored to the management of the dyslexia. Children with associated psychiatric disorders, including depression, anxiety, aggression, or oppositional behavior, can be managed by the child psychiatrist. Many children with dyslexia can become depressed due to the psychosocial impact of being taught separately from peers or the imposed academic expectations of parents who do not yet realize the child has a learning disorder.

Consultations

School consultations

The 2004 IDEA requires public schools to provide free and appropriate evaluations and education for children with learning disabilities. Because as many as 20% of all children may have phonologically based reading problems, not all children are evaluated by the school.

If a parent or health care provider suspects a significant reading problem, the parent should make a formal request (ie, a dated letter) for evaluation to the school and request to develop an appropriate individual education plan (IEP). With parental permission, a second letter from a health care provider requesting the evaluation often helps; however, the parent must make the initial request. Although state and local school district regulations differ, most districts must comply with a request for evaluation within 60 school days.

SPED services provided for a child with a reading disability typically include some time each day in a small group with a reading specialist. The child spends the remainder of the day in a standard classroom.

In addition to SPED, many elementary schools also offer the Title I enhanced reading program, which is designed to address the reading needs of economically disadvantaged children. In schools that offer the Title I program, a parental request for those services is often the sole requirement. No formal assessment is required for participation in Title I, although assessment might help some children. In many school districts, all reading programs in kindergarten and first and second grades are administered through the Title I mechanism; SPED is reserved for reading problems in the higher grades.

Intervention strategies

Reading problems affect many children; however, skillful early intervention at school or home can help ameliorate mild reading difficulties. The following strategies apply both to early intervention and to remedial work for an older child who reads poorly:

  • Phonemic awareness tasks in kindergarten include rhyming, making discriminations between similar but different words, blending sounds into words, isolating sounds from words, and segmenting words. These tasks prepare the child for reading, and all have shown some effectiveness in research settings.

  • Explicitly teaching children about segmenting and blending words has proven more effective in teaching reading than programs that do not explicitly teach those skills.

  • In first grade, explicit instruction in how the most common sounds are spelled enhances both reading and spelling skills.

  • Showing children how to sound out words and providing texts they can decode helps in practicing and retaining learned sound-spelling relationships.

Some schools do not emphasize these processes. The only option for children in these schools is to find an appropriate reading tutor or after-school reading programs. Programs that use the Orton-Gillingham or Lindamood-Bell methods have some success teaching students with reading disorders. Both systems emphasize sound recognition and sound-symbol relationships as the basis for reading.

Parents should evaluate private reading clinics and should also inquire about reading clinics offered by local colleges of education. Helpful software programs are also available to teach phonemic recognition; programs such as Reader Rabbit or Blues Clues can be effective adjuncts to tutoring and classroom intervention.

 

Medication

Medication Summary

For children with ADHD, appropriate stimulant treatment is indicated; otherwise, no medical treatment is suggested for reading problems.

 

Follow-up

Prognosis

Although parents assume that intervention will help their child catch up with peers, this notion is unsubstantiated by research data. In a Yale longitudinal study, persistently poor readers (ie, children identified in the early grades by their poor phonemic processing) continued to read more poorly than their nondisabled peers.[9] Although these children did learn to read, they continued to lag significantly behind peers throughout high school in decoding, reading rate, and accuracy. Despite poor scores in these areas, their overall reading comprehension scores were only mildly delayed. With persistent intervention and considerable personal effort, these children can achieve an adequate literacy level to function in society, although their reading abilities may still lag behind the skills of their peers.

Comorbidities

A widespread dilemma for physicians is when a child is failing in school and is suspected of having a reading disability, yet the school suspects the child has ADHD. Often, both educators and physicians delay evaluations and diagnosis while awaiting results from the other discipline. Although ADHD and a reading disorder are perceived as independent, significant overlap is observed.[11] In nonreferred epidemiological studies, children with a reading disorder are twice as likely as other children to have ADHD; the rate of such dual incidence approaches 15%. Conversely, individuals diagnosed with ADHD are also twice as likely to have phonological awareness problems directly related to a reading disorder; 36% of patients with ADHD have this difficulty. Comorbidity rates in clinically referred samples are higher, approaching 40% for both groups.

Social maladjustment is also more common in children with a reading disorder. Prevalence rates of anxiety, withdrawal, and depression are much higher than in peers without this disorder. Social problems become more pronounced as children age because they fall further behind in reading skills and in other subjects that require reading ability. Most children who have severe oppositional and conduct disorders have significant reading problems, which are often overlooked as school personnel attempt to cope with the conduct problems. Given that 40-60% of children with dyslexia suffer from depressive, anxiety or ADHD, and that the rate of suicidal behavior is higher in adolescents with dyslexia, children with reading disabilities should be screened for these psychiatric comorbidities.[13]

Children rarely have a single learning disability. Multiple learning disabilities can be expected because reading, spelling, listening, speaking, and writing all involve manipulations of the same linguistic system. Children who have difficulty with reading typically have difficulty with spelling. These difficulties are quite frustrating to parents and students. Parents commonly report working on spelling lists for hours to perfect performance the night before a test, only to have the child fail the test the next morning.

Logically, children who have difficulty spelling single words also have difficulty organizing and expressing more complex thoughts in writing. These children also tend to have difficulty with grammar and syntax. Difficulties become more pronounced in higher grades as instructors place more emphasis on written explanations. Reading disorders can also directly affect mathematics performance and grades, especially when children are required to read and understand word or story problems.