Classifying Specific Learning Disabilities: A Detailed Overview

When a child consistently struggles to read words their peers handle with ease, or cannot get their thoughts onto paper despite knowing exactly what they want to say, it raises an important question: is this simply a learning curve, or something more specific? Specific Learning Disabilities (SLDs) are neurodevelopmental conditions that affect how individuals acquire and use particular academic skills – not because of a lack of intelligence or effort, but because of how their brains process certain types of information. Getting the classification right is the first step to getting the support right.

What are specific learning disabilities? 🔗

According to the American Psychiatric Association, specific learning disorders are neurodevelopmental disorders typically diagnosed during the early school-age years, though they may not become apparent until academic demands increase. They are characterized by a persistent impairment in at least one of three major areas: reading, written expression, and/or math. An estimated 5 to 15% of school-age children struggle with a learning disability.

It is worth clarifying a common point of confusion: a “learning disorder” is a diagnostic term used by a licensed professional such as a psychologist, while “learning disability” is a legal term used by public schools based on assessments and documentation. In the U.S., the Individuals with Disabilities Education Act (IDEA) defines what a learning disability is. The concepts overlap significantly, but they operate in different systems – medical and educational respectively.

How SLDs are classified: the DSM-5 framework 🔗

The most widely used clinical classification system for SLDs is the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), published by the American Psychiatric Association. In 2013, the DSM-5 changed the diagnostic criteria for Specific Learning Disorder (SLD) to combine all three learning disorders – reading, mathematics, and written expression – into one overarching diagnosis. Rather than treating each domain as a separate condition, the DSM-5 uses a single diagnosis with “specifiers” to describe which academic area is affected.

These specifiers characterize the specific manifestations of learning difficulties at the time of assessment in three major academic domains: reading, writing, and mathematics. This approach better reflects the reality that many individuals experience difficulties across more than one domain, and that the boundaries between these domains are often blurry in practice.

SLD with impairment in reading (dyslexia) 🔗

The specifier “with impairment in reading” is added to the SLD diagnosis when a person demonstrates significant impairment in one or more reading subskills, including word reading accuracy, reading rate or fluency, and/or reading comprehension. Dyslexia may be used as an alternative term that refers to problems with word reading fluency or word reading accuracy, decoding, and spelling.

Dyslexia is the most prevalent form of SLD. In studies where every student is examined, as many as 21.5% are found to be dyslexic; in contrast, schools report less than 4 to 5%. This gap reveals how significantly the condition is underidentified in real-world educational settings. An estimated 80% of those with learning disorders have an impairment in reading, and dyslexia affects approximately 20% of the population – males and females equally.

SLD with impairment in written expression (dysgraphia) 🔗

The impaired subskills of SLD with impairment in written expression include spelling accuracy, grammar and punctuation accuracy, and clarity and organization of written expression. This goes beyond poor handwriting. It reflects difficulty in translating thoughts into coherent written language – a challenge that affects academic performance across virtually all subjects, not just writing classes.

Dysgraphia, the commonly used term for this condition, involves both motor and cognitive difficulties. A student may know what they want to write but struggle to coordinate the physical and linguistic processes needed to produce it accurately and fluently.

SLD with impairment in mathematics (dyscalculia) 🔗

The SLD specifier “with impairment in mathematics” applies to individuals who demonstrate significantly below-average skills in number sense, memorization of arithmetic facts, accurate or fluent calculation, and/or accurate math reasoning. The term “dyscalculia” describes difficulties with learning number-related concepts, processing numerical information, learning arithmetic facts, or using symbols and functions to perform accurate or fluent calculations.

The ICD-based criteria specify that a child’s arithmetical performance should be significantly below the level expected on the basis of age, general intelligence, and school placement, and performance is best assessed through an individually administered standardized test of arithmetic. Dyscalculia can also affect a child’s understanding of time, money management, and spatial reasoning – making it a challenge that extends well beyond the classroom.

Diagnostic criteria: what must be established 🔗

Diagnosing an SLD is not a single-step process. The DSM-5 requires that a student meet four criteria: persistent difficulties in reading, writing, arithmetic, or mathematical reasoning skills; academic skills that are well below average; learning difficulties that begin during the school-age years; and difficulties that significantly interfere with academic achievement, occupational performance, or daily living – and cannot be better explained by developmental, neurological, sensory, or motor disorders.

On the question of severity, difficulties must persist and fail to improve as expected, despite the provision of targeted, evidence-based intervention for at least six months. The difficulties must be assessed using standardised achievement tests and found to be at a level significantly lower than most individuals of the same age.

The DSM-5 considers “low achievement scores” to be at least 1.5 standard deviations below the population mean for age, though a more lenient threshold may be used when learning difficulties are supported by converging evidence from clinical assessment, academic history, school reports, or test scores.

Severity levels 🔗

Once diagnosed, SLD is classified at three levels of severity: mild, where some difficulties exist in one or two academic areas but may be compensated with accommodations; moderate, where significant difficulties require some specialized teaching and support; and severe, where even with accommodations, academic tasks may not be performed with efficiency. Specifying severity matters because it directly shapes the type and intensity of support a person needs.

The shift away from IQ-discrepancy models 🔗

One of the most significant changes introduced by the DSM-5 was the removal of the IQ-achievement discrepancy requirement – a model where a learning disability could only be diagnosed if a child’s academic performance fell significantly below what their measured IQ would predict. Previous DSM definitions used this “IQ-discrepancy model,” which allowed a child to be diagnosed with a learning disability only if there was a substantial difference between their tested general intelligence and their academic achievement. The new criteria mean that more children should have access to the reading interventions they need, including those with lower IQ scores above 70.

The DSM-5 definition of SLD states that diagnostic criteria do not depend upon comparisons with overall IQ, consistent with changes in the U.S. reauthorized IDEA regulations. This reflects a more inclusive and equitable approach to identification – one that focuses on functional impairment rather than the gap between potential and performance.

The challenges of diagnosing SLDs 🔗

Even with a clear framework in place, diagnosing SLDs accurately remains genuinely difficult. Several overlapping factors complicate the process.

Differential diagnosis and comorbidity 🔗

Differential diagnosis is necessary to distinguish learning disabilities from other disorders, syndromes, and factors that can interfere with academic skills. Intellectual limitations, sensory impairments, and adverse emotional, social, and environmental conditions may be the primary cause of low achievement and should not be conflated with SLD.

Specific learning disorders will not be diagnosed if there is a more plausible explanation for the difficulties – for example, if the individual has an intellectual disability, a sensory impairment, chronic absenteeism, inadequate proficiency in the language of instruction, or has not received appropriate instruction. These exclusion criteria are essential but also make diagnosis a nuanced, labour-intensive process.

Late and missed identification 🔗

Early identification of learning disabilities is crucial for providing timely interventions and improving educational outcomes. However, numerous challenges, including late diagnosis and ineffective screening methods, hinder timely identification.

Resource shortages worsen this problem significantly. The National Association of School Psychologists recommends schools hire one psychologist per 500 students, but the current national average for the 2022-2023 school year was one psychologist for every 1,119 students – meaning many students with learning disabilities may go undiagnosed, delaying appropriate supports and services.

Traditional screening methods also often fail to identify students who represent ethnic and racial minorities, leading to a disproportionate number of white and middle- to upper-class students receiving a diagnosis. This inequity in identification has lasting consequences for those who are left without support.

Psychometric data alone is not enough 🔗

Under DSM-5, psychometric data alone are insufficient for a diagnosis of SLD. A much closer collaboration is required between educators, clinicians, and parents, drawing on formal and informal school records, academic portfolios, instructional history, and information from psychoeducational and clinical assessments.

This shift reflects a more holistic understanding of learning difficulties – one that recognises that a test score does not capture the full picture of a child’s strengths, history, and context.

Why individualized assessment matters 🔗

Even after a diagnosis is made, the work is far from over. A diagnosis may explain the causes of a student’s learning difficulties, but it does not provide sufficient information about the type of services they may need, because learning disabilities affect individuals differently, even those with the same diagnosis. Each student should be assessed for individual learning strengths and challenges to identify appropriate supports.

A full evaluation for a learning disability includes a medical and neurological exam to rule out other causes, a review of developmental, social, and school performance, and usually involves a team of specialists – a psychologist, a special education expert, and a speech-language pathologist.

A key direction in the field is to move assessment from a static process focused on eligibility for services and diagnosis to a dynamic process oriented toward treatment and enhanced outcomes. Interventions should be explicit, customized, and address all of the individual child’s instructional needs, regardless of special education eligibility status or label.

The ultimate goal of classification is not to label a child but to understand them well enough to help them. An accurate, individualized assessment translates directly into better-targeted instruction, more meaningful accommodations, and a realistic pathway to success – in school and beyond. Though there is no cure for SLD, specific learning disorders can be successfully managed throughout one’s life, and people with SLDs can go on to become skilled learners, building on strengths that are often associated with their learning differences.

What do you think? Given that SLD classification has shifted away from IQ-discrepancy models toward a more holistic, multidisciplinary approach – do you think current school systems are equipped to implement this kind of thorough, individualized assessment for every child who needs it? And how might earlier identification change the long-term outcomes for individuals with SLDs who currently go undiagnosed well into adolescence or adulthood?

References

1. https://www.psychiatry.org/patients-families/specific-learning-disorder/what-is-specific-learning-disorder
2. https://www.psychiatry.org/File%20Library/Psychiatrists/Practice/DSM/APA_DSM-5-Specific-Learning-Disorder.pdf