1.7.3 Differentiating dyslexia from other developmental conditions
While dyslexia is distinctive, there are other developmental syndromes that often co-occur with it. Examples include:
developmental dysphasia – specific difficulties with spoken language
attention deficit/hyperactivity disorder – involving particular problems with concentration and/or behaviour
developmental dyspraxia – developmental coordination disorder.
Developmental dysphasia involves primary problems in the development of speech and language skills. Despite abilities in other areas, some children are slow to achieve the usual milestones in the development of spoken language, such as uttering their first words, putting together meaningful sentences, and/or understanding complex verbal instructions. It is perhaps unsurprising that these children can go on to show specific difficulties in acquiring the ability to write language.
Attention deficit/hyperactivity disorder (ADHD)
This refers to persistent and age inappropriate difficulties in regulating attention and/or behaviour. This diagnosis remains somewhat controversial, but it involves specific difficulties in either or both of two distinct dimensions:
inattention – difficulties maintaining concentration on the task in hand, high distractibility, working memory problems and tendencies to daydream
hyperactivity-impulsivity – excessive motor restlessness, and apparent difficulties in the inhibition of impulse, leading to inappropriate and often reckless behaviour.
Children may be diagnosed with ADHD if they show either or both of these kinds of problems, so there is considerable variability within such populations.
The overlap between dyslexia and ADHD is high (between 30 and 50 per cent in both directions), but it appears to be stronger for attentional problems than it is for the purely hyperactive-impulsive form of ADHD.
This broadly refers to specific difficulties in motor coordination (corresponding to the diagnosis used in the USA of ‘developmental coordination disorder’) but the term strictly refers to problems in the planning and execution of any complex, sequenced actions (including speech and writing). Dyspraxic children typically have difficulties in learning to do up buttons or tie their shoelaces, in balance and ball skills, and in copying and handwriting. Mothers often report that as babies they never went through the crawling stage, but simply got up and walked. At play or sports they appear ‘clumsy’, and they often show specific weaknesses in visual-perceptual skills and visual-motor coordination (relative to their other abilities) as well as marked attentional and organisational problems. The dyspraxia syndrome remains less widely recognised than dyslexia, but the overlap between the two appears to be very high, as around 50 per cent of dyspraxic children typically show dyslexic difficulties, and vice-versa.
In summary, there is considerable overlap between dyslexia and other abnormal developmental conditions such as dysphasia, ADHD and dyspraxia, although each syndrome can also occur in isolation. As well as their frequent co-occurrence in the same individual, these conditions also tend to associate within families, suggesting that there may be some common predisposing factors. We will return to this issue in Section 2 of this course.
Reread the case study of Alexander Faludy presented in Section 1.3. As well as dyslexia, does his account suggest features of any of the other conditions discussed here?
Box 5: Definitions
Acquired dyslexia: A form of dyslexia which is acquired as the result of neurological damage.