Learning disability

Overview
In the United States and Canada, the term learning disability (LD) refers to a group of disorders that affect a broad range of academic and functional skills including the ability to speak, listen, read, write, spell, reason and organize information.

A learning disability is not indicative of low intelligence. People with learning disabilities sometimes have difficulty achieving at his or her intellectual level because of a deficit in one or more of the ways the brain processes information.

Overview
- The National Joint Committee for Learning Disabilities (NJCLD) defines the term learning disability as "... a heterogeneous group of disorders manifested by significant difficulties in the acquisition and use of listening, speaking, reading, writing, reasoning or mathematical abilities. These disorders are intrinsic to the individual and presumed to be due to Central Nervous System Dysfunction. Even though a learning disability may occur concomitantly with other handicapping conditions (e.g. sensory impairment, mental retardation, social and emotional disturbance) or environmental influences (e.g. cultural differences, insufficient/inappropriate instruction, psychogenic factors) it is not the direct result of those conditions or influences." - The term referred to a discrepancy between a child’s apparent capacity to learn and his or her level of achievement.

Types of learning disabilities
Learning disabilities can be categorized either by the type of information processing that is affected or by the specific difficulties caused by a processing deficit.

Information Processing Deficits
The National Dissemination Center for Children with Disabilities (NICHY) states that learning disabilities fall into broad categories based on the four stages of information processing used in learning: input, integration, storage, and output.
 * Input
 * This is the information perceived through the senses, such as visual and auditory perception. Difficulties with visual perception can cause problems with recognizing the shape, position and size of items seen. There can be problems with sequencing, which can relate to deficits with processing time intervals or temporal perception.  Difficulties with auditory perception can make it difficult to screen out competing sounds in order to focus on one of them, such as the sound of the teacher's voice. Some children appear to be unable to process tactile input. For example, they may seem insensitive to pain or dislike being touched.


 * Integration
 * This is the stage during which perceived input is interpreted, categorized, placed in a sequence, or related to previous learning. Students with problems in these areas may be unable to tell a story in the correct sequence, unable to memorize sequences of information such as the days of the week, able to understand a new concept but be unable to generalize it to other areas of learning, or able to learn facts but be unable to put the facts together to see the "big picture." A poor vocabulary may contribute to problems with comprehension.


 * Storage
 * Problems with memory can occur with short-term or working memory, or with long-term memory. Most memory difficulties occur in the area of short-term memory, which can make it difficult to learn new material without many more repetitions than is usual. Difficulties with visual memory can impede learning to spell.


 * Output
 * Information comes out of the brain either through words, that is, language output, or through muscle activity, such as gesturing, writing or drawing. Difficulties with language output can create problems with spoken language, for example, answering a question on demand, in which one must retrieve information from storage, organize our thoughts, and put the thoughts into words before we speak. It can also cause trouble with written language for the same reasons. Difficulties with motor abilities can cause problems with gross and fine motor skills. People with gross motor difficulties may be clumsy, that is, they may be prone to stumbling, falling, or bumping into things. They may also have trouble running, climbing, or learning to ride a bicycle. People with small motor difficulties may have trouble buttoning shirts, tying shoelaces, or with handwriting.

Specific learning disabilities
Deficits in any area of information processing can manifest in a variety of specific learning disabilities.
 * Reading disability (ICD-10 and DSM-IV codes: F81.0/315.00)
 * The most common learning disability. Of all students with specific learning disabilities, 70%-80% have deficits in reading. The term "dyslexia" is often used as a synonym for reading disability; however, many researchers assert that there are different types of reading disabilities, of which dyslexia is one. A reading disability can affect any part of the reading process, including difficulty with accurate and/or fluent word recognition, word decoding, reading rate, prosody (oral reading with expression), and reading comprehension.
 * Common indicators of reading disability include difficulty with phonemic awareness -- the ability to blend sounds into words or break up words into their component sounds, and difficulty with matching letters or letter combinations to specific sounds (sound-symbol correspondence).


 * Writing disability (ICD-10 and DSM-IV codes F81.1/315.2)
 * Speech and language disorders can also be called Dysphasia/aphasia (coded F80.0-F80.2/315.31 in ICD-10 and DSM-IV).
 * Impaired written language ability may include impairments in handwriting, spelling, organization of ideas, and composition. The term "dysgraphia" is often used as an overarching term for all disorders of written expression. Others, such as the International Dyslexia Association, use the term "dysgraphia" exclusively to refer to difficulties with handwriting.


 * Math disability (ICD-10 and DSM-IV codes F81.2-3/315.1)
 * Sometimes called dyscalculia, a math disability can cause such difficulties as learning math concepts (such as quantity, place value, and time), difficulty memorizing math facts, difficulty organizing numbers, and understanding how problems are organized on the page.


 * Nonverbal learning disability [this disorder is not listed in the ICD-10]
 * Nonverbal learning disabilities often manifest in motor clumsiness, poor visual-spatial skills, problematic social relationships, difficulty with math, and poor organizational skills. These individuals often have specific strengths in the verbal domains, including early speech, large vocabulary, early reading and spelling skills, excellent rote-memory and auditory retention, and eloquent self-expression.


 * Dyspraxia
 * Sometimes called motor planning, dyspraxia refers to a variety of difficulties with motor skills. Dyspraxia can cause difficulty with single step tasks such as combing hair or waving goodbye, multi-step tasks like brushing teeth or getting dressed, or with establishing spatial relationships such as being able to accurately position one object in relation to another.

Difficulties that often co-occur with learning disabilities include difficulty with memory, social skills and executive functions (such as organizational skills and time management).
 * Disorders of speaking and listening

Diagnosis
The presence of a learning disability is sometimes suspected by a child's parents long before problems are seen at school. However, the issues typically become visible when a child begins having difficulty at school. Difficulty learning to read is often one of the first signs that a learning disability is present.

Learning disabilities are often identified by school psychologists, clinical psychologists, and neuropsychologists through a combination of intelligence testing, academic achievement testing, classroom performance, and social interaction and aptitude. Other areas of assessment may include perception, cognition, memory, attention, and language abilities. The resulting information is used to determine whether a child is achieving at his or her potential.

The DSM-IV, and many school systems and government programs have defined learning disabilities on the basis of a discrepancy between IQ scores and achievement scores. Although the discrepancy model has dominated the school system for many years, there has been substantial criticism of this approach (eg, Aaron, 1995, Flanagan and Mascolo, 2005) among researchers. Recent research has provided little evidence that a discrepancy between formally-measured IQ and achievement is a clear indicator of LD (Fletcher, 2003). Furthermore, diagnosing on the basis of a discrepancy does not predict the effectiveness of treatment. Low academic achievers who do not have a discrepancy with IQ (ie their IQ scores are also low) appear to benefit from treatment just as much as low academic achievers who do have a discrepancy with IQ (ie their IQ scores are higher).

Much current research has focused on a treatment-oriented diagnostic process known as response to intervention (RTI). Researcher recommendations for implementing such a model include early screening for all students, placing students having difficulty in research-based early intervention programs, and closely monitoring the progress of identified students to determine whether increasingly intense intervention results in adequate progress (Fletcher, 2003). Those who do not respond adequately to intervention can then be referred for further assistance through special education. A primary benefit of such a model is that it would not be necessary to wait for a child to be sufficiently far behind to qualify for assistance (Lyon, et al, 2001). This may enable more children to receive assistance before experiencing significant failure, which may in turn result in fewer children who need intensive and expensive special education services.

Assessment
Many normed assessments can be used in evaluating skills in the primary academic domains: reading, not including word recognition, fluency, and comprehension; mathematics, including computation and problem solving; and written expression, including handwriting, spelling and composition.

The most commonly used comprehensive achievement tests include the Woodcock-Johnson III (WJ III), Weschler Individual achievement Test II (WIAT II), the Wide Range Achievement Test III (WRAT III), and the Stanford Achievement Test–10th edition. These tests include measures of many academic domains that are reliable in identifying areas of difficulty.

In the reading domain, there are also specialized tests that can be used to obtain details about specific reading deficits. Assessments that measure multiple domains of reading include Gray's Diagnostic Reading Tests–2nd edition (GDRT II) and the Stanford Diagnostic Reading Assessment. Assessments that measure reading subskills include Gray's Oral Reading Test IV – Fourth Edition (GORT IV), Gray's Silent Reading Test, Comprehensive Test of Phonological Processing (CTOPP), Tests of Oral Reading and Comprehension Skills (TORCS), Test of Reading Comprehention 3 (TORC-3), Test of Word Reading Efficiency (TOWRE), and the Test of Reading Fluency. A more comprehensive list of reading assessments may be obtained from the Southwest Educational Development Laboratory.

Of course, assessment of learning disabilities requires the consideration of more than test scores. The purpose of assessment is to determine what is needed for intervention, which also requires consideration of contextual variables and whether there are comorbid disorders that must also be identified and treated, such as behavioral issues or language delays.

Treatment and Intervention
Poor academic achievement can be addressed with a variety of interventions. Although the underlying processing difficulty is usually considered to be a lifelong disorder, academic skills themselves can be improved with targeted interventions. Some (adjustments, equipment and assistants) are designed to accommodate or help compensate for the disabilities while others (specialized instruction) are intended to make improvements in the weak areas. Practice is a particularly important component in developing competence, regardless of the starting point. Children who start out with a weakness in a basic skill, such as reading, may miss out on the necessary practice because of the need to catch up with their chronological age peers. Thus a small weakness can snowball into a larger problem.

Interventions include:


 * Mastery Model:
 * Learners work at their own level of mastery.
 * Practice
 * Gain fundamental skills before moving onto the next level
 * Note: this approach is most likely to be used with adult learners or outside the mainstream school system.


 * Direct Instruction:
 * Highly structured, intensive instruction
 * Emphasizes carefully planned lessons for small learning increments
 * Scripted lesson plans
 * Rapid-paced interaction between teacher and students
 * Correcting mistakes immediately
 * Achievement-based grouping
 * Frequent progress assessments


 * Classroom adjustments:
 * Special seating assignments
 * Alternative or modified assignments
 * Modified testing procedures


 * Special equipment:
 * Electronic spellers and dictionaries
 * Word processors
 * Talking calculators
 * Books on tape


 * Classroom assistants:
 * Note-takers
 * Readers
 * Proofreaders


 * Special Education:
 * Prescribed hours in a special class
 * Placement in a special class
 * Enrollment in a special school for learning disabled students

Sternberg has argued that early remediation can greatly reduce the number of children meeting diagnostic criteria for learning disabilities. He has also suggested that the focus on learning disabilities and the provision of accommodations in school fails to acknowledge that people have a range of strengths and weaknesses, and places undue emphasis on academic success by insisting that people should receive additional support in this arena but not in music or sports.

Causes and Risk Factors
The causes for learning disabilities are not well understood, and sometimes there is no apparent cause for a learning disability. However, some causes of neurological impairments include:


 * Heredity -- Learning disabilities often run in the family.
 * Problems during pregnancy and birth -- Learning disabilities can result from anomalies in the developing brain, illness or injury, fetal exposure to alcohol or drugs, low birth weight, oxygen deprivation, or by premature or prolonged labor.
 * Accidents after birth -- Learning disabilities can also be caused by head injuries, malnutrition, or by toxic exposure (such as heavy metals or pesticides).

Impact on Affected Individuals
Individuals with a learning disability may isolate themselves from society as they may feel:


 * Ashamed of the types of difficulties they struggle with, such as poor literacy skills, attention or memory difficulties
 * Fear of failure, criticism, ridicule or rejection
 * Fear that others may think that they are stupid or incapable
 * Ashamed that they are unable to read or that they have poor handwriting
 * Left out of every day discussions due to lack of understanding
 * Depressed
 * Alone

Impact on society
Statistical and demographic studies show that society pays a high cost for untreated learning disabilities because of the disproportionate number of individuals with LD who are unemployed, receive public assistance, who commit crimes, who go to juvenile courts, who are held in a juvenile detention facility, and who go to prison.


 * Unemployment
 * About 75% of unemployed adults are illiterate.


 * Welfare


 * According to a study conducted by the Center for Law and Social Policy, 25%-35% of former participants in a federal welfare-to-work program had learning disabilities, 85% of whom had not been identified as learning disabled by the public schools.


 * The New York State Rehabilitation Association estimates that 25%-40% of individuals with learning disabilities receive public assistance.


 * Rhode Island found that 21 percent of a sample of new welfare applicants between May 1997 and February 1998 had a learning disability.


 * Gender issues


 * Research shows that as many girls as boys have learning disabilities, but that girls are less aggressive and outspoken in elementary school, resulting in girls who have learning disabilities unidentified and untreated.  However, according to the National Institute for Literacy, about three boys are determined to have a learning disability for every girl who is so determined. Dr. Reid Lyon of the National Institutes of Health explains that girls display fewer disruptive behaviors in elementary school than boys, so girls with learning disabilities are often unnoticed and untreated.


 * The failure of some schools to identify learning disabilities among young girls is one explanation researchers offer for the significant number of welfare recipients with learning disabilities.  According to the an issues brief prepared by the National Governors’ Association, the significant number of welfare recipients with learning disabilities can be explained in part by the failure of some schools to identify learning disabilities among young girls.


 * Crime and prison population


 * Approximately 80% of prison inmates are reported to be functionally illiterate.   These inmates cannot read or write well enough to find an intersection on a map, apply for a Social Security card, or write a simple letter.


 * Researchers found that a majority of inmates who were reading below high school levels showed signs of moderate to severe decoding and word recognition problems. That is, they had dyslexia, a reading disability.


 * Approximately 40% of youth held in detention facilities have some form of learning disability, such as dyslexia.

Contrast with other conditions
People with an IQ lower than 70 are usually characterized as having mental retardation (MR), mental deficiency, or cognitive impairment and are not included under most definitions of learning disabilities, because their learning difficulties are related directly to their low IQ scores.

Attention-deficit hyperactivity disorder (ADHD) is often studied in connection with learning disabilities, but it is not actually included in the standard definitions of learning disabilities. An individual with ADHD may struggle with learning, but he or she can often learn adequately once successfully treated for the ADHD. A person can have ADHD but not learning disabilities or have learning disabilities without having ADHD. The conditions can co-occur (see Comorbidity). In order to understand the difference, imagine that someone with a learning disability is affected in only one or a few areas. However, people with ADHD are often affected in all areas. ADHD is also caused by chemical imbalances rather than the physical differences in the brain that cause Dyslexia.

Some research is beginning to make a case for ADHD's being included in the definition of LDs, since it is being shown to have a strong impact on "executive functions" required for learning (planning, organization, etc). This has not as yet affected any official definitions.