Specific learning disability

Prevalent, but often difficult to pin down

Specific learning disability (SLD) is the most prevalent of the neurodevelopmental disorders. It is commonly known as phonological dyslexia, which means, ‘a disorder of reading and spelling’, but this makes up only one component of the difficulties that may be encountered. Neurodevelopmental disorders appear early in life and feature a strong genetic or familial origin. There is also a high level of co-occurrence between them, with individuals likely to experience more than one type of these types of disorders. We need a holistic approach to their definition, assessment and prognosis. Currently, these disorders are placed in their own discrete diagnostic ‘silos’, based on pre-existing disciplines, but a more integrated and triangulated approach may be necessary.

Many psychologists prefer working with adults, and often regard SLD as a childhood issue and perhaps beyond their jurisdiction. However, unrecognised SLD contributes to many adult mental health presentations. Every practitioner should be aware of this diagnosis and be equipped with the tools to recognise it. This article addresses that need, as well as locates SLD in a multidisciplinary framework.

Defining SLD

The common starting point for classification in Australia has been the Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM-5; American Psychiatric Association, 2013). The DSM-5 provides an overarching diagnosis of SLD, with six specific deficits:

• Word reading
• Reading comprehension
• Spelling
• Written expression
• Mathematical operations
• Mathematical reasoning

Each deficit could occur independently and show persistence for at least six months despite provision for help (Blythe, 2014). These skills form the core of our primary education system, what are traditionally termed ‘the three Rs’ of reading, writing and arithmetic. The term ‘specific’ was used to differentiate from a more general cognitive or learning deficit, mostly mild intellectual disability.

SLD is constantly classified within a cluster of disorders that pertain to speech and oral communication. Oral language develops rapidly in the context of maternal attachment and immediate family dynamics and is highly developed by the time a child commences school. Conversely, literacy and numeracy begin in the family setting but require prolonged and intensive formal instruction to reach the level of proficiency required in a modern society.

How then do disorders in developmental processes that are acquired so differently, and with distinct sequences, really connect when there appears to be comorbidity or co-occurrence between them? What do we make of children who meet criteria for both SLD and a language disorder? A useful starting point is to consider some common labels found within the present neurodevelopmental disorders umbrella and some of the common comorbidity disorders.

SLD is constantly classified within a cluster of disorders that pertain to speech and oral communication

SLD and auditory processing disorder (APD)

The term APD has become popular among parents and teachers as a childhood diagnosis. It refers to a significant deficit in the processing of speech input, and allegedly explains various problems in coping, especially in listening to the teacher or parent. Many private audiologists in Australia currently offer an assessment service for APD, with formal report typically provided.

Despite this, the validity of APD protocols has been repeatedly challenged over confusion between ‘auditory’ and ‘attentional’ problems (Bench et al., 2016; Moss et al., 1994). Construct validity has been unclear due to multiple non-auditory factors (DeBonis, 2015). There are no agreed diagnostic criteria or intervention strategies (Beck et al., 2016). In my practice, numerous children who initially presented with a prior APD diagnosis were invariably found to meet all the criteria for SLD. The APD diagnosis was redundant for intervention purposes.

APD has also given rise to commercial ‘listening’ products that entailed passive listening to taped music or sounds. No enhancement of performance has resulted. Unfortunately their use is not regulated under AHPRA guidelines; APD continues to be used as a diagnostic label, to the detriment of many children.

SLD and dyspraxia

Dyspraxia or developmental coordination disorder (DCD) is another neurodevelopmental disorder within DSM-5. In the past, state education departments screened and assisted clumsy children through their physical education branches. These initiatives have mostly lapsed. Clumsiness is now not targeted as a concern unless a parent takes the initiative privately. More recently DCD was claimed to co-occur with SLD, the primary indicator being messy, uneven and poorly controlled handwriting.

In my practice, handwriting was examined in two ways. First, parents were asked to provide bipolar ratings of a range of gross and fine motor skills, as part of a developmental profile. These ratings confirmed messy, uneven handwriting was a common problem for children presenting with SLD. However there were no signs of other fine motor difficulty (e.g., using scissors, tracing, drawing within lines, bead threading, replicating hand movements etc.). This suggested that poor handwriting was not a distinct DCD indicator. Early fine motor difficulties were most commonly associated with generalised immaturity, especially in boys, which was unconnected to either DCD or SLD. There was no suggestion that SLD children displayed inherent problems of clumsiness. Messy handwriting appeared to be primarily due to lack of explicit teaching.

A second metric was a standardised speeded sentence copying task, originally developed by occupational therapists (OTs) dealing with messy handwriting concerns (Wallen et al., 1996). It can be tested reliably in one minute and is preferable to speeded copying of individual words or letters. Such a task consistently revealed that children and adults with SLD were very slow in handwriting. It appeared to be a valid diagnostic indicator of SLD and reflect a processing-speed deficit typically measured by speeded (rapid) naming tasks. A rapid naming deficit typifies poor readers, most of whom have SLD. The speed component of handwriting thus needs to be interpreted separately from other learnt indicators such as irregular letter shape, uneven letter height, letter-spacing difficulties etc.

SLD and attention-deficit hyperactivity disorder (ADHD)

Children with SLD typically display normal executive skills of attention, concentration, distractibility and perseverance in a testing situation, even while delayed in literacy and numeracy skills. Yet parents and teachers describe widespread executive difficulties and organisation problems. Children rarely complete homework or most assigned tasks. Standardised rating scales are typically scored severely, and often lead to a label of ADHD, and possible use of stimulant medication. It is necessary to be very cautious about extrapolating from composite scores based on the summation of ratings (Rowe & Rowe, 2004). It is wrong to presume an ADHD diagnosis in isolation for what is actually SLD.

ADHD can be comorbid with SLD, but this is rare in practice. In most cases, executive difficulties are a corollary of the academic challenges being faced by the child. The starting point should always be examination of literacy and numeracy difficulties. If executive difficulties are suspected, a more broadly based examination in multiple settings is necessary. These are available in rating format in commercial standardised or informal checklists. Many children with ADHD actually perform well in literacy and numeracy tasks, but struggle specifically with organisation and planning aspects. They cannot meet deadlines or get work finished. Anecdotally SLD and ADHD do often get confused due to the incomplete assessment process and misunderstanding of the validity of rating scales.

SLD and autism spectrum disorder (ASD)

ASD is a core neurodevelopmental disorder, the most common form being high functioning, and still commonly labelled Asperger syndrome. Diagnosis remains problematic due to its contextual character. The custodial parent typically identifies signs more intensely at home. ASD can be less obvious to the teacher or psychologist; disputes over diagnosis are commonplace. Comorbidity with other neurodevelopmental disorders can be overlooked. However my practice indicates that ASD, in its high-functioning form, has high comorbidity with SLD. Consequently any child or adolescent suspected of ASD warrants examination of literacy and numeracy skills as part of the diagnostic protocol. This information is key to holistic management.

It remains problematic how this comorbidity should be integrated with the emergent picture of other language/communication/learning difficulties. The dynamic remains unclear. Social-pragmatic language difficulties, by themselves or as part of ASD, continue to be differentiated from other communication difficulties. Children with severe communication difficulties can also have underlying ASD that goes unrecognised, especially in females, ‘hidden’ by the obvious language problems.

SLD and language disability

Problems with phonological processing may well be a defining feature of SLD. Some tests measure a variety of phonological awareness skills, others combine elements into a composite score, with no indication that one skill deficit has greater predictive validity in directing the way the child is taught. In any event, the phonological difficulty is evident in the pattern of spelling and word reading errors.

A second defining measure is serial naming speed – the time taken to name a set of random repeated visual images. Children and adults with reading difficulties have slower processing speed, which varies with the stimulus. A broad-spectrum test of varying stimulus cards is preferable (e.g., RAN/RAS). This naming deficit occurs in tandem with slow handwriting speed.

A third defining measure has variously been termed listening skill, auditory processing, or auditory short-term memory. Children with SLD often do not seem to listen effectively or absorb a limited amount of spoken information. This has often been measured with a sentence repetition task or a digit span retention test. These measures of auditory capacity connect closely to observations from parent or teacher about poor listening skills. They can be confused with executive/attention issues, as happened with the APD protocols.

A diagnosis of SLD should thus include not only standardised testing of word reading, spelling, writing and number skills, but examination of listening and executive skills. A developmental learning history form, containing bipolar ratings by the parent, has been found to be one convenient way to gather this information. Such a form can assess listening skills, executive skills and gross/fine motor skills readily. Bipolar ratings are more valid than Likert-style ratings (Rowe & Rowe, 2004).

A broader definition of SLD as both a school learning and a language disorder is linked with a speech-sound disorder (SSD) and a developmental language disorder (DLD) as currently defined by DSM-5. All children with a language disorder, whether short term (SSD) or chronic (DLD), will display delay in reading and spelling skills. This is more pronounced when there is co-morbid SLD.

The pattern of errors is similar. Is there a definition issue? Does a child (or adult) with a communication disorder have comorbid SLD, or is it intrinsically part of the communication disorder per se? Do ‘pure’ SSD cases typically ‘outgrow’ their early literacy difficulties?

This leads to the suggestion that a practitioner who assesses a language disorder (most commonly a speech pathologist) must also include standardised testing of reading and spelling – and probably numeracy – in their examination. Likewise a practitioner who identifies SLD needs to be alert to the possibility of subtle language difficulties. These may not be self-evident and must be identified by relying on the experience of a parent, carer or partner.

SLD assessment and testing

SLD is evident in subtle language difficulties in the preschool years but has frequently not been recognised as such. Use of a parent checklist like the developmental learning history form indicates the following profile of common problems:

• Early language delay
• Early auditory memory problems (remembering phone numbers, addresses etc.)
• Blurred speech/confused sounds/speech clarity issues
• Frequent reliance on others to speak on behalf of the child
• Problems in following directions at home and at school
• Problems in learning number order
• Problems of attention, concentration and restlessness, which rarely meet criteria for ADHD

Once schooling starts, a significant delay in learning the alphabet and recognising basic vowel sounds is evident immediately. The typical SLD child displays word reading, spelling and number results in the lowest 13–15 percentile range. Children with identified comorbid language problems (e.g., DLD, SSD) tend to score even lower in reading and spelling. Longer-term patterns and prognosis are unclear.

The child is invariably delayed across all literacy and numeracy areas; there is never any indication of separation into dyslexia and dyscalculia sub-types. Assessment at any age should include testing for all skills.

Reversals of letters and numerals are common, but do not have any predictive utility. Problems of phonological awareness (phoneme confusion) are evident in word reading and spelling errors from the outset. Focused phonological awareness testing is useful but not essential in making an SLD diagnosis. Separate reading comprehension testing is not needed except in specialist circumstances.

The child typically has awkward, messy handwriting. All find writing a chore; output is invariably limited. Messy handwriting does not appear to be connected to other issues of motor clumsiness. A brief handwriting speed test is inevitably indicative of SLD , as is naming speed. A naming speed test is always corroborative of SLD, but often not essential for diagnosis.

By third grade the measurement of numeracy skills should include speeded recall of basic addition and subtraction. It is thereafter desirable to include both an untimed test of basic arithmetic skills and a timed test of rapid recall of number facts. Available speeded tests include a WIAT-3 sub-test, the Dyscalculia Screening Test, and the TRMA (Test of Rapid Mental Arithmetic). Only the TRMA gives a complete profile of all four processes, including switching between signs.

A wide selection of standardised achievement tests for word reading, spelling and number skills is available, with comparable validity and reliability, so choice is discretionary. Tests which have psychometric scaling of item difficulty, commonly based on Rasch Scaling, do offer significant advantages in shortening testing time and facilitating monitoring of progress. An assessment of writing fluent sentences is desirable from age seven. Standardised tests are available (cf WIAT–3), but informal writing samples are equally suitable. Some tests are standardised across the life span (e.g., WJ5, WRAT5), but one can extrapolate using tests standardised up to age 18 without loss of validity.

An assessment of cognitive abilities is not necessary to diagnose SLD. However verbally advanced children, especially girls, sometimes ‘hide’ or mask their SLD, especially in their word reading. It may be necessary to include extra measures of vocabulary skill and/or verbal reasoning. A broader cognitive profile may be useful for older secondary/young adults in relation to vocational guidance issues, if time permits.

SLD has little impact on the social-emotional adjustment of some children, but leads to somatic distress, sleep disturbance, anxiety or loss of confidence/self-esteem in others. The DLHF can be useful in identifying these issues. Subsequent counselling from about age eight to nine is helpful, emphasising that SLD is a ‘family’ matter.

Prognosis for SLD is highly variable. Some children outgrow their reading difficulties in later secondary school. Poor spelling is managed by many through the use of spellcheck software. Poor spelling remains a robust indicator of SLD in adults, as does speeded recall of basic number facts. Many adults adopt compensatory strategies in their vocation, so SLD-related issues remain undetected. A significant proportion of children drop out in early secondary years. Some present later with self-harm, alcohol and other drug issues and suicidal ideation. Some go on to university study, but sometimes university counselling services are ill-equipped to recognise them.

Any practitioner needs to be familiar with a core toolkit. Children with significant academic delay of any form, listening difficulties, somatic complaints, sleep difficulties or executive issues should be considered potential SLD. A developmental learning history form should be employed if possible, as well as whatever is available from the class teacher.

The toolkit for adults suspected of SLD depends on context. Testing of word reading is primary, while a spelling test is nearly always revealing. Arithmetic/numeracy skill deficits can persist too, but their pertinence depends on the vocational situation. An oral vocabulary test (e.g., word definitions) can sometimes be helpful too. Broader cognitive testing is seldom necessary. This profile must be integrated with the person’s schooling and employment history, to determine what intervention might assist.

Contact the author: [email protected]