The association between specific learning difficulties, or dyslexia, and ADHD is complex and has been further complicated by widely differing views and approaches used in different countries and by different professionals, making it difficult to evaluate research and clinical experience.
An appreciation of the possible co-existence of specific learning difficulties and ADHD is necessary, for all aspects to be appropriately managed. Dyslexia can cause inattentiveness in a classroom situation, but should not do so outside the class setting. Whilst learning delay occurs in 90% of children with ADHD, largely due to concentration and other ADHD difficulties, this must be distinguished from language based specific learning reading and spelling problems, and non-verbal maths, and spatial difficulties, or other disorders. These are best thought of as relatively fixed problems, which do not generally improve with medical management in the same way as do the ADHD symptoms. There may be problems with written language, visual and auditory perception, processing problems and/or language difficulties in 20-30% of children, in addition to their ADHD. Conversely, up ton 30% of children with specific learning difficulties have associated ADHD.
The acknowledgement that ADHD can co-exist with other conditions, especially specific learning difficulties, is crucial. In these children, the ability to learn is doubly compromised by their additional poor concentration. Such children are at exceptionally high risk of failure. Accurate early diagnosis and management of both their co-existing conditions, i.e. ADHD and the specific learning difficulties, is essential to avoid progressive under-achievement, diminished self-esteem and social skills and increased oppositionality and frustration.
In the UK, the term “dyslexia” is widely used: ADHD is not dyslexia and dyslexia is not ADHD, although they frequently co-exist. Dyslexia checklists frequently include comments regarding poor concentration, short-term memory difficulties and easy distractibility, and dyslexia has been used as a broad umbrella for almost any learning problem. Specifically the areas of specific learning difficulties is probably more helpful than continuing to use the term dyslexia. Children with co-existing ADHD must be diagnosed as such to enable more effective management of their problems. In fact, in some children with severe ADHD, appropriate assessment of associated specific learning difficulties is not truly possible until the ADHD component has been effectively managed. This may mean a re-assessment after some months or years, to decide how much of the child’s condition is due to the ADHD symptoms and how much is due to specific learning difficulties. A child with significant specific learning difficulties needs an educational psychology assessment; by a professional who understands both dyslexia and ADHD. It is most useful to regard specific learning problems, including dyslexia, as those which persist once the co-existing ADHD, if present, has been satisfactory managed.
Many children with ADHD have problems in auditory short-term memory and auditory processing and commonly, when there is associated dyslexia, there may also be problems in visual memory and processing also. When auditory processing difficulties are severe, the child may have central auditory processing disorder. In this situation, there are severe problems in learning from listening, in sound localisation and lateralisation and in the discrimination and recognition of auditory input. This may come to be regarded as a separate co-existing condition with ADHD.
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