Nature

The nature and developmental trajectory of dyslexia depends on multiple genetic and environmental influences.

Manifestation

Dyslexia is a set of processing difficulties that affect the acquisition of reading and spelling.

The most commonly observed cognitive impairment in dyslexia is a difficulty in phonological processing (i.e. in phonological awareness, phonological processing speed or phonological memory).

However, phonological difficulties do not fully explain the variability that is observed. Working memory, processing speed and orthographic skills can contribute to the impact of dyslexia.

Impact

In dyslexia, some or all aspects of literacy attainment are weak in relation to age, standard teaching and instruction, and level of other attainments.

Across languages and age groups, difficulties in reading and spelling fluency are a key marker of dyslexia.

Variance and co-occurrence

Dyslexic difficulties exist on a continuum and can be experienced to various degrees of severity.

Dyslexia can affect the acquisition of other skills, such as mathematics, reading comprehension or learning another language.

Dyslexia frequently co-occurs with one or more other developmental difficulties, including developmental language disorder, dyscalculia, ADHD, and developmental coordination disorder.

This is the Delphi definition of dyslexia written by Carroll, J., Holden, C., Kirby, P., Snowling, M. J., & Thompson, P.A. (2024).

Features: A specific learning difficulty in mathematics is a set of processing difficulties that affects the acquisition of arithmetic and other areas of mathematics.

In dyscalculia, the most commonly observed cognitive impairment is a pronounced and persistent difficulty with numerical magnitude processing and understanding that presents in age related difficulties with naming, ordering and comparing physical quantities and numbers, estimating and place value.

Some individuals may not present with a specific cognitive impairment in numerical magnitude processing but have an equally debilitating specific learning difficulty (SpLD in mathematics) due to other processing difficulties. Difficulties in language, executive function (verbal and visuo-spatial working memory, inhibitory control) and visual-spatial processing may also contribute.

Impact: Mathematics is a very varied discipline. Difficulties with learning mathematics may present in specific areas (for example, basic calculation) or across of the mathematics studied by the individual in relation to age, standard teaching and instruction, and level of other attainments. Across education systems and age groups, difficulties in arithmetic fluency and flexibility and mathematical problem solving are key markers of a SpLD in mathematics. Persistent difficulties in mathematics can have a significant impact on life, learning and work. This may also have a detrimental impact upon an individual’s resilience to apply mathematical skills effectively.

Presentation: The presentation and developmental trajectory of a specific learning difficulty (SpLD) in mathematics depends on the interactions of multiple genetic and environmental influences. It will persist through life but may change in manifestation and severity at different stages.

A SpLD in mathematics frequently co-occurs with one or more of the following: attention deficit hyperactivity disorder (ADHD), dyslexia, developmental language disorder (DLD) and developmental coordination disorder (DCD).

Maths anxiety commonly co-occurs with a SpLD in mathematics but is not an indicator in itself.

This definition was published by the SpLD Assessment Standards Committee (SASC) in March 2025.

In the UK, dyslexia and dyscalculia can be diagnosed by:

• Specialist Teacher Assessors

• Educational Psychologists

I trained via the ‘Specialist Teacher Assessor’ route due to my background as a Special Educational Needs Coordinator (SENCo).

The work of specialist teacher assessors is moderated and supported by the SpLD Assessment Standards Committee (SASC) and an Assessment Practising Certificate (APC) is issued to assessors who have met the relevant guidance.

This includes the regular submission of reports (for moderation) and a commitment to participating in ongoing professional development.

It is worth being aware that some specialist assessors may not have an up-to-date APC but may still conduct assessments privately. You can check if your specialist teacher assessor has an up-to-date APC on the SASC website.

If a dyslexia report is used as evidence to apply for Disabled Students’ Allowance funding in higher education, the report must be written by an APC holder.

I hold an up-to-date APC and my number is: 25/APC03038

The SpLD Assessment Standards Committee (SASC) recently published the following advice to specialist assessors:

"For young children under the age of 8 years, formative and ongoing assessment with recommendations for intervention is likely to be more appropriate than reaching a diagnostic conclusion ... "

I usually assess students who are aged 8+.

However, I will occasionally consider conducting a dyslexia assessment for a pupil who is aged 7.5 onwards, if the following information is available:

- The pupil participated in a program of structured systematic phonics teaching/intervention throughout Year 2

- There is a family history of dyslexia, and/or

- The student had an early history of speech and language difficulties.

I have extensive experience of working with students in Key Stage One and I am aware of the risk factors that can be relevant. On some occasions, it can be appropraite to conduct a full diagnostic assessment between the end of Year 2/Year 3, or at the start of Year 3.

This is my professional opinion and other professionals may disagree with me.

Please arrange a call to discuss further if required.

A dyslexia diagnosis conducted at any age is valid for life and so all professionals in the community have a duty to think very carefully about whether it is appropriate to make a formal diagnosis, to ensure the judgement is correct.

I only conduct dyscalculia assessments from age 8 onwards.

The scores obtained in an assessment may show eligibility for exam ‘access arrangements’, according to STA criteria in Year 6, or JCQ criteria in secondary schools.

There are a range of access arrangements, including extra time, that can be considered for a pupil with SEN.

A diagnosis, in itself, is not required for a pupil to be considered for extra time.

In addition to reporting scores in the relevant fields, schools are encouraged to implement a ‘normal way of working’ and report a ‘history of need’.

This form is completed when an application for extra time is made in secondary schools.

The scores obtained in a private assessment report can be used on this form, if the private assessor (ie. me) and the school have established a ‘working relationship’ in advance of the assessment and shared a partially completed Form 8 in advance too.

I am happy and willing to complete Form 8s, where relevant, and I do not charge anything additional for this service.

A diagnosis of dyslexia is valid for life and students do not need to be assessed again in the future.

An assessment conducted at any age can be used in applications for Disabled Students’ Allowance (DSA) in higher education.

However, if the original assessment showed eligibility for exam access arrangements, some sub-tests would need to be completed again to see if eligibility remains.

The student would not need to seek another diagnostic assessment and be ‘re-diagnosed’.

Yes. I have worked extensively with a (wonderful) diverse range of pupils over the years. I have also consulted with numerous specialists possessing other areas of expertise.

I am always happy to discuss ‘the whole child’ in more detail.

ADHD and ASD can only be formally assessed by an appropriately qualified medical professional.

Although many traits can overlap, it is usually necessary to seek a diagnosis for each condition separately (at present – this may evolve in time and it is an interesting area for further discussion).

Yes, the findings of a diagnostic assessment for dyslexia and/or dyscalculia may help to provide information about the nature, extent and context of your child’s special educational needs.

It may helpful to talk to the Special Educational Needs Coordinator in your child’s school about this process too.

I provide an assessment service and there are times when the assessment will lead to a formal diagnosis and times when it will not.

The assessment process and the opportunity to consult with a professional in the field can be helpful for families who are trying to navigate a complex system, even if a diagnosis is not made.

I always make recommendations linked to the assessment findings, even if the student is not formally diagnosed with dyslexia or dyscalculia.

This can provide interesting information about areas that are not commonly measured within the school context. Eg. working memory.

I usually find that families are interested in the level of detail related to individual strengths and weaknesses that are highlighted in a report.

The tasks in an assessment morning are broken up carefully to ensure the student does not feel too tired or overwhelmed.

The student will have the opportunity to visit the garden, take breaks, play games and access sensory resources as appropriate.

I offer a split assessment over two sessions for students who need to work in smaller chunks and families are encouraged to request this at the booking stage.

A combined assessment for dyslexia and maths difficutlies/dyscalculia will always be split across two sessions.