Differentiating Specific Learning Disabilities from Other Disorders

When a child struggles to read, write, or do math despite consistent effort and instruction, the first instinct might be to label it a learning problem – but the real question is: what kind? Diagnosing a Specific Learning Disability (SLD) is not as simple as observing a child fall behind in school. Clinicians and educators must work through a rigorous process of differential diagnosis – systematically ruling out other explanations before confirming that a true SLD is present. Getting this right matters enormously, because the right diagnosis leads to the right support.

What is differential diagnosis in the context of SLD? 🔗

Differential diagnosis is the process by which a clinically significant problem is evaluated and distinguished from other conditions that may present with similar features. In the case of SLD, this means systematically examining whether a child’s learning difficulties stem from the disability itself – or from another underlying condition that simply looks like one. According to the American Psychiatric Association, SLD is a neurodevelopmental disorder characterized by persistent impairment in reading, written expression, or mathematics – but the diagnosis requires that these difficulties meet specific criteria and cannot be better explained by other factors.

The DSM-5 criteria for SLD involve four criteria (A through D), all of which must be satisfied. Criterion D, specifically, captures all exclusionary factors – stating that learning difficulties must not be better accounted for by general low intelligence, sensory deficits, other medical or neurological conditions, lack of language proficiency, psychosocial adversity, or inadequate educational instruction.

Exclusion criteria: what SLD must not stem from 🔗

Before an SLD diagnosis can be confirmed, professionals must rule out several primary causes of poor academic performance. These are not minor technicalities – they are the foundation of accurate diagnosis.

Vision and hearing impairments 🔗

A child who cannot see the board clearly or hear the teacher well will inevitably struggle academically. These sensory deficits must be screened and ruled out before considering SLD. Research published in PMC emphasizes that the differential diagnostic process must rule out sensory conditions, approaching assessment by taking into account documentation of the child’s health history, unique developmental profile, and detailed test interpretation in a multidimensional context to determine the precise causes of learning impairment. A child who struggles to read because of uncorrected visual impairment does not have SLD – they need glasses and perhaps remedial support, not a learning disability classification.

Intellectual disability 🔗

SLD and intellectual disability (formerly called mental retardation) are considered mutually exclusive diagnoses – an IQ in the range required for a diagnosis of intellectual disability is listed among the exclusionary criteria for learning disabilities. This distinction is important: a child with an intellectual disability has a broad, generalized impairment in cognitive functioning and adaptive behavior, whereas a child with SLD has a narrow, specific impairment in one or more academic domains while general intelligence remains within normal limits. In SLD, adaptive impairment is restricted to domains influenced by reading, math, and writing skills, and does not result in a general lack of independence or difficulty with daily living activities.

Environmental deprivation and inadequate instruction 🔗

A child who has had limited access to quality education, who has experienced significant socioeconomic disadvantage, or who has been raised in a language-impoverished environment may fall behind academically – but this is not an SLD. The National Joint Committee on Learning Disabilities (NJCLD) has clearly stated that intellectual limitations, sensory impairments, and adverse emotional, social, and environmental conditions may be the primary cause of low achievement and must not be confused with SLD. Similarly, children who are English language learners face a particular challenge: academic difficulties may arise primarily because they are learning content while simultaneously mastering a second language – a situation that requires careful consideration so that students are not misidentified as having SLD simply due to limited English proficiency.

The ICD-10 framework echoes these exclusions, specifying that SLD is not simply a consequence of a lack of opportunity to learn, nor of any acquired brain trauma or disease, and that the impairment must be specific – not solely explained by lower general intelligence. Additionally, learning difficulties that rapidly improve with increased support at home or school are less likely to represent a true SLD.

Co-existing conditions: when other disorders share the picture 🔗

One of the most clinically challenging aspects of SLD diagnosis is that several other conditions can co-exist with it, mimic it, or even mask it. Distinguishing these overlapping presentations requires careful, multi-source assessment.

ADHD and SLD: a frequent and complex overlap 🔗

ADHD and SLD are both classified as neurodevelopmental disorders in the DSM-5, and they frequently occur together. Research indicates that around 25% of children with SLD have a comorbid ADHD diagnosis, and conversely, studies suggest that 31-45% of children with ADHD also have a specific learning disability. This overlap creates a genuine diagnostic challenge: a child struggling in reading or writing may appear inattentive – not because they have ADHD, but because the academic task is frustrating and beyond their current ability. The inattention is secondary to the SLD, not a primary disorder of attention.

Clinical guidelines recommend that a comprehensive psychoeducational assessment be completed to tease apart the primary diagnosis, or to confirm whether both disorders are comorbid. A key distinction: children with ADHD show performance deficits – they have the skill but fail to apply it consistently – while children with SLD show true skill deficits that persist regardless of effort or motivation. Because ADHD significantly interferes with cognitive testing, it is standard clinical practice to treat ADHD first before proceeding with intelligence assessment, so that ADHD symptoms do not confound IQ test results.

Anxiety and SLD 🔗

Anxiety is another condition that can both accompany and complicate the diagnosis of SLD. A child who has been struggling academically for years often develops significant anxiety around school tasks – test anxiety, fear of reading aloud, avoidance of homework. This anxiety may become so prominent that it appears to be the primary problem. Research highlights that anxiety can limit the effectiveness of standalone academic interventions, meaning that if the anxiety is not addressed alongside the SLD, treatment outcomes are poorer. Clinicians must determine whether anxiety is a consequence of the learning difficulties, a co-occurring independent disorder, or the primary driver of academic underperformance. Studies comparing children with SLD and ADHD find that children with SLD tend to score higher on anxiety measures, suggesting that anxiety is a particularly common emotional companion to learning difficulties.

Other conditions to consider 🔗

The differential diagnostic net must also account for autism spectrum disorder (ASD), conduct disorders, depression, language disorders, and auditory processing disorders – all of which can affect academic performance in ways that superficially resemble SLD. Before a diagnosis of SLD is made, clinicians are expected to rule out neurological disorders, motor impairments, emotional issues, and language barriers as primary causes of poor academic performance. Each of these conditions has its own diagnostic criteria, presentation patterns, and treatment pathways – and confusing them with SLD leads to misclassification and inappropriate support.

The role of professionals in the diagnostic process 🔗

Given how many conditions can look like SLD, accurate diagnosis depends on a comprehensive, multi-disciplinary assessment – not a single test or a teacher’s observation alone.

Comprehensive assessment: what it involves 🔗

The American Psychiatric Association states that an SLD diagnosis is made through a combination of observation, clinical interviews, family history, school reports, and standardized neuropsychological testing. A full neuropsychological evaluation typically includes measures of intelligence, academic achievement, attention, memory, processing speed, language abilities, visual-spatial skills, fine motor skills, and social-emotional functioning. Such an evaluation allows a clinician to differentially diagnose SLD, ADHD, and other conditions, and to understand the neurodevelopmental underpinnings of a child’s learning difficulties in a comprehensive, rather than piecemeal, way.

Collaboration between clinicians and educators 🔗

The International Dyslexia Association notes that the DSM-5 criteria require much closer collaboration between educators, clinicians, and parents than previous editions did. Psychometric data alone is no longer sufficient for a DSM-5 SLD diagnosis – the assessment must draw on formal and informal school records, academic portfolios, instructional history, and input from multiple informants including parents and teachers. This means that the diagnostic process is inherently collaborative: a school psychologist brings data about academic performance and classroom behavior, while a clinical neuropsychologist can conduct more complex cognitive testing, and a physician rules out medical causes such as seizure disorders or motor impairments.

Why accurate diagnosis matters 🔗

The NJCLD has warned that inappropriate diagnostic practices have contributed to the misclassification of individuals – both incorrectly including people whose problems are not attributable to SLD, and incorrectly excluding those whose difficulties genuinely are SLD. Both errors are harmful. A child incorrectly labeled with SLD may miss appropriate intervention for the actual cause of their difficulties. A child with genuine SLD who goes undiagnosed may spend years struggling in a system that doesn’t understand their needs. The goal of differential diagnosis is not to create barriers to diagnosis – it is to ensure that each child receives a precise, evidence-based explanation for their difficulties, and with it, the most effective support possible.

What do you think? If two children show identical reading difficulties in the classroom, what factors do you believe are most important in distinguishing whether one has a true SLD and the other does not? And how should schools and clinicians better collaborate to prevent children from being either over-diagnosed or under-diagnosed with SLD?

References

1. https://www.ncbi.nlm.nih.gov/books/NBK207533/
2. https://www.psychiatry.org/patients-families/specific-learning-disorder/what-is-specific-learning-disorder
3. https://dyslexiaida.org/dsm-5-changes-in-diagnostic-criteria-for-specific-learning-disabilities-sld1-what-are-the-implications/
4. https://pmc.ncbi.nlm.nih.gov/articles/PMC10795803/
5. https://www.asha.org/policy/tr1994-00140/
6. https://pmc.ncbi.nlm.nih.gov/articles/PMC6345134/
7. https://pmc.ncbi.nlm.nih.gov/articles/PMC10756621/
8. https://caddra.ca/pdfs/caddraGuidelines2011Chapter02.pdf
9. https://nasenjournals.onlinelibrary.wiley.com/doi/abs/10.1111/1471-3802.12633
10. https://www.medicalhomeportal.org/clinical-practice/education-and-schools/specific-learning-disability