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Specific Learning Disorder (SLD) - 'Inability to read, write, or calculate' is a brain characteristic -

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"I can't remember kanji no matter how many times I practice," "I freeze up when it's time to read aloud," "I just can't do calculations." Many parents are worried after seeing their children struggle in these ways.

When a child has specific, extreme difficulties in learning despite having no intellectual delays, it may not be due to "laziness" or "lack of practice," but rather related to characteristics of the brain's information processing. Medically, this condition is called "Specific Learning Disorder (SLD)," and in educational settings, it is referred to as "Learning Disabilities (LD)."

With proper understanding and support tailored to the child, the path to learning can be opened. In this article, from the perspective of a pediatric neurologist, I have compiled the information necessary for parents to take their "next step," including the brain science background of SLD, the diagnostic process in Japan, evidence-based support methods, and how to request reasonable accommodations at school.


📌 What you will learn in this article

  • What is Specific Learning Disorder (SLD)? - 3 types and the brain science background

  • Prevalence in Japan and what the MEXT survey revealed

  • Why is there high comorbidity with other neurodevelopmental disorders like ADHD and ASD?

  • The diagnostic process and testing tools available in Japan (STRAW-R, KABC-II, etc.)

  • Evidence-based support methods - What can be done at home and at school

  • Concrete examples of reasonable accommodations and what parents should know


🔹 What is Specific Learning Disorder (SLD)?

Specific Learning Disorder (SLD) is a neurodevelopmental disorder (developmental disability) that refers to a state where, despite having no delays in general intellectual ability, only specific learning areas such as reading, writing, and calculation are significantly lower than the level expected for the child's age and intelligence. DSM-5-TR (American Psychiatric Association, 2022) calls it "Specific Learning Disorder," while Japan's Act on Support for Persons with Developmental Disabilities calls it "Learning Disabilities (LD)," both referring to the same concept.

The important point is that the cause of SLD is a functional characteristic of the central nervous system, and it is not caused by "the child's lack of effort" or "the parents' way of raising them." We consider the possibility of SLD when there are no problems with vision or hearing, and learning difficulties persist despite being provided with an appropriate educational environment.

What experts look for
In diagnosing SLD, the "discrepancy between intellectual ability and academic achievement" is key. However, since DSM-5, it is no longer just a difference between IQ and achievement; it is judged comprehensively from both 1) falling below the age-appropriate level on standardized academic tests, and 2) not improving even with appropriate intervention (RTI model). Even in the definition by the Ministry of Education, Culture, Sports, Science and Technology (MEXT), "significant learning difficulties" is not a medical diagnosis itself but a screening based on educational evaluation, and the final diagnosis is made at a specialized medical institution.

🔹 3 types and main symptoms

In DSM-5-TR, SLD is classified into the following three subtypes. Each involves different processing circuits in the brain.

In reality, difficulties in reading and writing often overlap (if reading is difficult, writing is often difficult as well), and it is sometimes called "developmental reading and writing disorder." Also, when "learning disabilities" are viewed broadly, reading difficulties (dyslexia) are considered to account for the largest proportion, and there are reports that reading impairment is the main symptom in about 80% of SLD cases.

🔹 What we know from brain science

SLD is a disorder based on characteristics of brain structure and function, and a significant body of brain imaging research has been accumulated, particularly regarding dyslexia.

Brain networks in dyslexia

In the normal reading process, three regions in the left hemisphere of the brain work in coordination.

Meta-analyses of fMRI studies show that children with dyslexia exhibit consistent hypoactivation in the left temporoparietal and left occipitotemporal regions compared to typically developing children at the same reading level, suggesting this is not merely a "developmental delay" but a qualitatively different brain characteristic (Shaywitz & Shaywitz, 2008; Richlan, 2014). Systematic reviews of DTI (diffusion tensor imaging) (Martins et al., 2024) have also confirmed changes in the white matter structure of the left arcuate fasciculus and corona radiata. However, DTI is currently positioned as research-based evidence and is not a diagnostic test for clinical use.

In dyscalculia, functional and structural changes have been reported in the intraparietal sulcus involved in numerical processing (Rykhlevskaia et al., 2009).

What experts are looking at
The core of dyslexia is phonological processing disorder (difficulty in recognizing the sound units that make up language). Because Japanese hiragana are syllabic characters with relatively regular character-sound correspondences, accuracy deficits may be milder than in alphabetic language regions, but decreased reading fluency (speed) is a more sensitive indicator. Since kanji require more complex phonological and morphological processing, a characteristic of Japanese speakers is that many show specific difficulties in writing kanji.

🔹 How many children are affected? - Prevalence and MEXT survey

Global and Japanese prevalence

The lower prevalence of dyslexia among Japanese speakers compared to alphabetic language regions is thought to be partly due to the regular character-sound correspondence of hiragana and katakana. However, when kanji are included, the percentage of children with reading and writing difficulties is higher.


Ministry of Education, Culture, Sports, Science and Technology (MEXT) 2022 National Survey

In 2022, MEXT conducted a "Survey on Students in Regular Classes Requiring Special Educational Support" (Target: approximately 88,500 public elementary, junior high, and high school students). The main results are as follows.


Main results of the MEXT survey (2022)

  • Students with no delay in intellectual development but who "show significant difficulties in learning or behavior": 8.8% (an increase from 6.5% in the previous 2012 survey). This is not a prevalence based on diagnosis, but an estimate of educational support needs

  • A ratio of about 3 students in a class of 35

  • "Show significant difficulties in learning" (equivalent to SLD): 4.5% in the previous survey 4.5%

  • The background to this increase is believed to be the spread of awareness regarding developmental disorders

※ This survey is a screening based on behavioral observation by homeroom teachers and is not a medical diagnosis.

🔹 Comorbidity with other neurodevelopmental disorders - Why SLD rarely occurs in isolation

SLD has a high rate of comorbidity with other neurodevelopmental disorders. This is not a "coincidental overlap" but is thought to be based on shared genetic foundations and overlapping neural circuits.

Comorbidity with ADHD is particularly important clinically. A review (DuPaul et al., 2013) reported an average ADHD-SLD comorbidity rate of 45.1%, and when writing disorders are included, the trend is higher than previous estimates. Because the "inattention" symptoms of ADHD and the "reading and writing difficulties" of SLD have similar behavioral expressions, it is important to carefully evaluate which is the primary difficulty.

"Academic delay" does not always mean SLD
There are many factors other than SLD that cause academic underachievement. Differential diagnosis is necessary, including Intellectual Developmental Disorder (IDD), ADHD alone (academic decline due to inattention), ASD (bias in learning style), vision/hearing problems, emotional issues, and loss of learning opportunities due to school non-attendance. That is why comprehensive evaluation at a specialized institution is important.

Regarding reading and writing difficulties in children who are "intellectually slow"
Even for children who are told that their overall development is slightly slow in intelligence tests, there are cases where they struggle with reading and writing more than would be predicted from their intellectual level. For example, there are cases where they can manage conversation and daily life reasonably well, but are extremely poor only at reading and writing characters. In such cases, there is a possibility that brain characteristics related to reading and writing (such as difficulty with phonological processing) are overlapping, separate from intellectual delay There is value in taking specialized reading and writing tests such as STRAW-R so as not to miss opportunities for support by saying "it can't be helped because the IQ is low." Regardless of whether a diagnosis is made, knowing "what this child is particularly struggling with" is the first step toward appropriate support The relationship between intellectual developmental disorder and SLD will be explained in detail in a separate article for professionals.

🔹 The flow of diagnosis available in Japan

The diagnosis of SLD proceeds in stages. The general flow is: screening at school or health checkups → comprehensive evaluation at a specialized medical institution → diagnosis and support planning.

Step 1: Awareness and screening

It starts with the school teacher, school counselor, or guardian noticing that "there is a significant difficulty in reading, writing, or calculation compared to children of the same grade." If there is a learning delay of two or more grades, it is considered highly likely to be SLD.

Step 2: Intelligence test

Evaluation of intellectual ability is essential for the diagnosis of SLD, as it is a prerequisite to confirm that "there is no delay in general intellectual ability."

Step 3: Evaluation of learning achievement (reading, writing, calculation)

SLD cannot be determined by WISC alone. Standardized tests specialized for reading, writing, and calculation are indispensable.

What experts are looking at
What is particularly important in the diagnosis of SLD in Japanese is "reading fluency (speed)". Since hiragana has regular character-sound correspondence, difficulties are easily overlooked if only accuracy is checked, but when reading speed is measured, dyslexic children show a clear difference from typically developing children. The speed reading task of STRAW-R is designed exactly for this purpose. Also, a decrease in RAN (Rapid Automatized Naming: rapid naming of colors, numbers, etc.) is well known internationally as a cognitive marker for dyslexia.


Step 4: Differential diagnosis and evaluation of comorbidities

The following evaluations are also performed as necessary.

  • Visual function test (exclusion of convergence insufficiency and eye movement problems)

  • Auditory/speech discrimination test (differential diagnosis of auditory processing disorder)

  • Evaluation of comorbidities such as ADHD/ASD (questionnaires, behavioral observation)

  • Head MRI/EEG (when exclusion of epilepsy or organic disease is necessary)

Where to visit: You can receive evaluations at pediatric neurology departments, child psychiatry departments, developmental support centers, and educational consultation offices attached to universities.

It takes time to get a diagnosis - The reality in Japan and what you can do "while waiting"


It is not uncommon for it to take six months to over a year to complete all of the above steps 1-4. The waiting time for the first visit to a developmental outpatient clinic ranges from several months to over half a year depending on the region, and WISC-V alone takes 1-2 hours, and STRAW-R or KABC-II often require appointments on separate days, so it is not always possible to receive all tests at one facility. In the meantime, the school grade advances, and the child's "sense of trouble" accumulates. However, there are many things you can start without waiting for a diagnosis to be confirmed.

  • Grasp the direction with minimal testing: First, WISC-V + STRAW-R if you have these two, you can confirm the discrepancy between intellectual level and reading/writing, and establish a rough direction for support. There is no need to wait for all tests to be completed.

  • Consultation with the school is possible before diagnosis: Consultations with the homeroom teacher or special needs education coordinator, and consultations regarding the use of special needs classes, can be started even without a medical certificate.

  • DAISY textbooks can be requested without a diagnosis: If it is 'difficult to read with regular textbooks,' parents can apply directly even without a medical diagnosis.

  • Use the school counselor as a 'bridge': While waiting for a medical appointment, having school observation information shared with the school counselor will provide valuable data for the consultation.

There is no need to assume that 'nothing can be done without a diagnosis.' If you are concerned, I recommend starting to move with both the school and a medical institution at the same time.

🔹 Evidence-based support and intervention

There is no 'magic bullet' for SLD, but it has been proven through fMRI research that appropriate educational intervention can reorganize the brain's reading circuits (neuroplasticity). The finding that activity in the left temporoparietal region of children with dyslexia increased after intervention is important evidence showing that 'the brain can change.'

Intervention for reading and writing disorders

A large-scale meta-analysis summarizing 40 years of intervention research (Hall et al., 2023; 53 studies, 6,053 participants) has yielded the following results:

Key findings from the dyslexia intervention meta-analysis (Hall et al., 2023)

  • Overall effect size of multi-component interventions centered on systematic and explicit phonics (letter-sound correspondence) instruction: g = 0.33 (statistically significant, p < .001). While improvement can be expected on average, individual differences are large, and adjustments to the intensity and content of support are a prerequisite.

  • Interventions including phonological awareness instruction are the most effective.

  • The greater the total dosage of intervention, the greater the effect.

  • Effect on word reading/spelling > Effect on reading comprehension

  • Interventions implemented by teachers > Interventions implemented by paraprofessionals or volunteers

Furthermore, an RCT meta-analysis (Galuschka et al., 2014) concluded that phonics instruction was the only intervention method that showed a statistically significant effect on reading and writing performance. On the other hand, the effectiveness of morpheme-based instruction (such as instruction focusing on the meaning of kanji radicals and components) has also been suggested as age increases.

Intervention for dyscalculia

Although research on interventions for dyscalculia is still limited compared to dyslexia, building number concepts through the manipulation of concrete objects (blocks, number lines, etc.), and explicit and staged instruction in small groups are considered effective.

RTI Model (Response to Intervention)

In recent years, the RTI model (multi-tiered system of support) has been recommended as an international standard.

What experts are looking at
As a point to note in intervention research, it is known that even with research-based interventions, a certain percentage of children do not respond sufficiently. Some reports indicate that approximately 20-25% of students with learning disabilities may not fully benefit from reading interventions provided at school (Austin et al., 2017). In other words, one approach does not improve every child, and customizing support to fit individual cognitive characteristics is important. In Japanese SLD support, it is required to individually plan 'which notation to start from and which cognitive route to use for practice' based on the results of STRAW-R and KABC-II.

🔹 Reasonable accommodations available at school

Due to the Act on the Elimination of Discrimination against Persons with Disabilities enacted in 2016, the provision of reasonable accommodations in public schools has become a legal obligation. For private businesses, including private schools, it was initially an obligation of endeavor, but it was changed to a legal obligation starting April 1, 2024 (Cabinet Office, 2024). Here are examples of reasonable accommodations that children with SLD can receive.

To receive reasonable accommodations, objective test data such as STRAW-R is effective as a basis. Especially when applying for extended time on entrance exams, the results of speed reading tasks become important documentation. The first step is to consult with the homeroom teacher or the special needs education coordinator and have it discussed by the school committee.

Link collection useful when requesting reasonable accommodations from school

Point:A medical certificate is not legally required to apply for reasonable accommodations, but attaching test results from STRAW-R or WISC-V increases persuasiveness. It is effective to include a summary of test results and specific accommodation requests in a 'Support Book' and hand it to the homeroom teacher during the meeting at the beginning of the school year.

🔹 ICT utilization and ingenuity that can be done at home

Technology can be a powerful ally for children with SLD.

What can be done at home - Useful link collection

【Audio Teaching Materials/Digital Textbooks】

【Reading and Writing Training】

【Free Learning Worksheets and Materials】

  • Surapuri — Free learning worksheets for developmental disabilities. Designed to accumulate 'I did it!' moments through small steps

  • Special Needs Education Exciting Materials — Various free materials such as eye movement training, character searching, and kanji decomposition quizzes

Tip: The key to home-based efforts is 'short time, fun, and a little bit every day.' In addition to paper and pencils, prioritize methods that allow your child to feel they have 'succeeded' by using tablet 'tracing apps' or voice input. If writing is difficult, starting touch-typing practice from the middle grades of elementary school will make learning much easier from junior high school onwards.

🔹 To Parents — Things you should know

  • They are not 'being lazy'. SLD is a characteristic of brain information processing, not a matter of the individual's motivation or effort.

  • It cannot be 'cured,' but it can be 'improved'. Appropriate intervention can reorganize the brain's reading circuits. Early detection and early support are important.

  • Developing 'strengths' is the key to protecting self-esteem. Even if reading and writing are difficult, oral comprehension, thinking skills, and artistic or athletic abilities are often preserved.

  • 'Reasonable accommodation' is not special treatment, but a guarantee of fair learning opportunities. Just like wearing glasses, ICT and extended time are tools that enable a way of learning that suits the child.

  • Please do not carry the burden alone. There are multiple places to consult, such as pediatric neurology clinics, developmental support centers, and educational counseling offices.

Children with SLD are not 'unable to read or write,' they just 'find it difficult to learn using the same methods as everyone else.' Finding the method that suits the child is the key to opening the door to learning.


Evidence and References

[1] American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR). APA Publishing, 2022.

[2] Ministry of Education, Culture, Sports, Science and Technology (MEXT). 'Survey Results on Children Requiring Special Educational Support Enrolled in Regular Classes (2022)' December 2022.

[3] Shaywitz SE, Shaywitz BA. Paying attention to reading: The neurobiology of reading and dyslexia. Dev Psychopathol. 2008;20(4):1329-1349. PMID: 18838044

[4] Richlan F. Developmental dyslexia: Dysfunction of a left hemisphere reading network. Front Hum Neurosci. 2014;8:1-17. PMID: 24578692

[5] Rykhlevskaia E, et al. Neuroanatomical correlates of developmental dyscalculia: Combined evidence from morphometry and tractography. Front Hum Neurosci. 2009;3:51. PMID: 20046826

[6] Hall C, et al. Forty years of reading intervention research for elementary students with or at risk for dyslexia: A systematic review and meta-analysis. Read Res Q. 2023;58(2):285-312.

[7] Galuschka K, et al. Effectiveness of treatment approaches for children and adolescents with reading disabilities: A meta-analysis of randomized controlled trials. PLoS ONE. 2014;9(2):e89900. PMID: 24587113

[8] DuPaul GJ, et al. Comorbidity of LD and ADHD: Implications of DSM-5 for assessment and treatment. J Learn Disabil. 2013;46(1):43-51. PMID: 23144063

[9] Developmental Disorder Information and Support Center. 'Specific Learning Disorder'. https://hattatsu.go.jp/supporter/healthcare_health/about-sld/

[10] Uno A, Haruhara N, Kaneko M, Wydell TN. Revised Standardized Reading and Writing Screening Test (STRAW-R). Interna Shuppan, 2017.

[11] Koeda T, Seki A. Theory and Practice of T-style Hiragana Reading Support: From Dyslexia to Children Who Struggle with Reading.

[12] Inagaki M (Ed.). Practical Guidelines for the Diagnosis and Treatment of Specific Developmental Disorders. Shindan to Chiryo Sha, 2010.

[13] Snowling MJ, et al. Developmental outcomes for children at high risk of dyslexia and children with developmental language disorder. Child Dev. 2019;90(5):e548-e564. PMID: 30206938

[14] McGrath LM, Stoodley CJ. Are there shared neural correlates between dyslexia and ADHD? A meta-analysis of voxel-based morphometry studies. J Neurodevelop Disord. 2019;11(1):31. PMID: 31752679

[15] van Bergen E, et al. Co-occurrence and causality among ADHD, dyslexia, and dyscalculia. Psychol Sci. 2025;36(1). PMID: 39718009

[16] Austin CR, et al. Reading interventions for inadequate responders: A systematic review and meta-analysis. J Learn Disabil. 2017;50(4):416-431. PMID: 26825689

[17] Martins TBT, et al. White matter alterations in developmental dyslexia: A systematic review of diffusion tensor imaging studies. Brain Imaging Behav. 2024;18:1170-1186.

[18] Cabinet Office. 'Act on the Promotion of the Elimination of Discrimination on the Basis of Disability' (Effective April 1, 2024). https://www8.cao.go.jp/shougai/suishin/sabekai.html

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