Three Levels of Assessment:
1. Impairment or Disturbance
It is helpful to understand that there are three main levels to any neurodevelopmental assessment such that answers can be provided about diagnosis and disability. The first is determining whether there is an impairment and/or disturbance. In order for someone to have a disability according to the Equality Act 2010, they must have an impairment.
For a DSM-5 diagnosis to be given, a disturbance in cognition, emotion regulation or behaviour needs to be identified that reflects a dysfunction in the psychological, biological, or developmental processes underlying mental functioning.
They are, in fact, the only real hurdles that need to be overcome in terms of understanding whether someone has a disability, and therefore might be entitled to reasonable adjustments, or whether a diagnosis is appropriate: the next levels are really just detail about these.
2. Functional Problem or Deficit
The Functional Problem level is what tells us about the nature of the disability and/or diagnosis. A functional problem could be finding word reading very difficult, or not being able to sit still, or finding it very difficult to plan and carry out work, or any other difficulty, either observable or internal. This can be assessed by interview, observation, questionnaire and/or tests of attainment.
If it is clear that there is a developmental deficit “…with onset in the developmental period … that produces impairments of personal, social, academic, or occupational functioning” then it will be appropriate to give a diagnosis of a neurodevelopmental disorder. This might not be the only type of diagnosis that is given as people with NDD also often have mental health problems too.
3. Neuropsychology
Finally, we come to the neuropsychological level. This is what is assessed by using cognitive measures like the WISC and BADS-C. It is important to recognise that it is never essential to have formal neuropsychological or cognitive test results in order to say that someone has a disability: in fact, it is not even necessary to have a diagnosis to be recognised as having a disability. It is also rarely necessary to have such test results to be given a NDD diagnosis: a diagnosis can be given on the basis of an assessment of the functional problem, the test results simply add detail and specificity.
Case example
John has real problems producing written work in school despite being able to answer things verbally. This means he has fallen far behind his peer group for literacy and this has been getting worse for at least two years.
From this, it is already clear that John has a disability and is very likely to receive a diagnosis. It is also likely that any diagnoses will include an NDD.
Clinical assessment reveals significant functional impairments in word reading ability and handwriting. It is also clear that this has always been the case and he has rarely spontaneously picked up a pencil or pen. He is also clumsy on a gross motor level, knocking things over, walking into things and finding it very difficult to play ball sports etc. John is therefore given appropriate diagnoses of Specific Learning Disorder with Impairment in Reading (DSM-5 code 315.00) and Developmental Coordination Disorder (code 315.4).
However, the neuropsychological assessments show that John also has real problems with visual scanning and executive functioning. These significantly contribute to his problems in education as they make classroom work very difficult and mean that he cannot plan his academic activities without support. There is no further specific diagnosis that these issues form part of, so he is also appropriately diagnosed with Other Specified Neurodevelopmental Disorder: Neurodevelopmental Disorder Relating to Academic Functioning (Associated with Weak Visual Scanning and Executive Functioning) (code 315.8): this is the code for when something does not fit the current standard criteria.
Avoiding confusion
It is important to recognise here that all diagnoses are given in relation to an identified functional problem: without any such problem, there could be no diagnosis but, importantly, the clinically-identified presence of such a problem means that a diagnosis is warranted even if nothing more is known about it at that stage. In such circumstances, a diagnosis of Unspecified Neurodevelopmental Disorder (code 315.9) could be given in the interim.
It is the same with disability: an identified impairment that has a substantial and long-term effect on a person’s ability to carry out normal day-to-day activities constitutes a disability even in the absence of a formal clinical assessment or diagnosis.
Confusion can arise about these levels of assessment for several reasons. Quite often, the terms relating to the Impairment/Disturbance and Functional Problem levels are used interchangeably or combined in the same sentence that makes it hard to know what is being referred to (e.g. an impairment in reading). This is partly a result of the somewhat different but overlapping terminology used in relation to disability versus diagnosis. This does not usually cause any real difficulty as it is generally clear what is being conveyed.
The real confusion can arise when a diagnostic label is used to reference both the Functional Problem level and the Neuropsychological level. For example, dyslexia is often used to mean both the general collection of issues to do with literacy that encompasses poor reading and writing (functional problems visible in the classroom) and also poor phonological awareness, working memory or executive skills (all of which require some sort of neuropsychological assessment). In essence, this is an unnecessary jumble of effects and causes because a diagnosis does not need to specify the causes – it simply describes the effects of the underlying causes (which may not be known).
Implications for support
A key reason why this matters is that the recommendations that make a difference most often flow from the neuropsychological examination of underlying causal factors – and if there is confusion about what is a cause and what an effect, the recommendations can become muddied. Also, lots of NDD share a variety of common underlying causes – and if some causes are thought to be somehow intrinsically linked with a particular diagnosis, it leads to a lack of clarity about what is actually going on (e.g. problems with handwriting, which is a motor control issue, come to be thought of as something inherently to do with dyslexia).
So, non-standard diagnostic terms like dyslexia are not necessarily problematic but they do tend to lead to additional confusion about the proper assessment of functional problems and their underlying neuropsychological causes.
Accordingly, the DSM highlights: “Dyslexia is [a] term used to refer to a pattern of learning difficulties characterised by problems with accurate or fluent word recognition, poor decoding, and poor spelling abilities. If dyslexia is used to specify this particular pattern of difficulties, it is important also to specify any additional difficulties that are present, such as difficulties with reading comprehension or math reasoning.”
Similarly, the significant UK report, Identifying and Teaching Children and Young People with Dyslexia and Literacy Difficulties (2009) says: “Dyslexia is a learning difficulty that primarily affects the skills involved in accurate and fluent word reading and spelling. Characteristic features of dyslexia are difficulties in phonological awareness, verbal memory and verbal processing speed… Co-occurring difficulties may be seen in aspects of language, motor co-ordination, mental calculation, concentration and personal organisation, but these are not, by themselves, markers of dyslexia… Phonological awareness, verbal memory and verbal processing speed are all aspects of phonological processing and a convincing body of evidence shows that difficulties with them are reliable markers of dyslexia.”
The points made clearly in that report are that (i) dyslexia is a problem with word read and spelling (ii) it is underpinned by specific neuropsychological causes to do with phonological processing and (iii) there are a variety of co-occurring neuropsychological characteristics that are not specifically markers of dyslexia and which are common to many NDD.
What is particularly important is that a non-standard term like dyslexia or dyspraxia does not come to just mean any of the variety of underlying causal or associated neuropsychological factors that are common to many NDD: such terminology creep tends to be associated with a reduction in precision and clarity – and, hence, effectiveness of support.
Footnote on diagnosis vs disability
It is quite possible in general to have a diagnosis without meeting the criteria for having a disability. This is because there are a number of diagnostic categories that do not require the effects to be long-term (i.e. lasting 12 months or more): you might have a short-lived anxiety disorder, example. In general, though, any diagnosed NDD will also meet the disability criteria because, by definition, an NDD relates to childhood development and its effects would be expected to last 12 months or more.
You can also have a disability without meeting the criteria for a diagnosis despite the similarity of definitions: if you have a disability, it is by definition something that goes beyond the normal differences in ability which may exist among people and which has an adverse effect on your ability to carry out normal day-to-day activities. If, in the words of the Equality Act, this is due to a mental impairment, you would expect that to warrant a diagnosis of some sort, either of an NDD or a mental health condition. The exceptions to this are the Specific Learning Disorders as one of the key diagnostic criteria is that they persist despite the provision of interventions that target those difficulties: until such interventions have been provided, you might meet the definition for having a disability but a diagnosis could not yet be given. You can also have a disability due to cumulative impairments, but where no single aspect of those impairments reaches diagnostic thresholds for a specific disorder.
Read more about diagnosis, disability and the Disabled Students' Allowance
