Comorbidity

As with other developmental disorders, in dyslexia comorbidity with other childhood disorders is the rule rather than the exception (Box 1). Two types of comorbidity can be identified: other co-occurring developmental disorders and comorbid psychiatric disorders. In addition, emotional problems as consequences of dyslexia are common and may be very disabling.

Developmental disorders that commonly co-occur with dyslexia include specific language impairment (Reference Catts, Adlof and HoganCatts 2005), specific arithmetic disorder (Reference Lewis, Hitch and WalkerLewis 1994), developmental coordination disorder (Reference Kaplan, Wilson and DeweyKaplan 1998) and autism-spectrum disorders (Reference Reitzel, Szatmari and PriorReitzel 2003). Although precise prevalence rates of comorbidity have not been documented, it is common to find considerable overlap among these disorders. Indeed, some authorities feel that they all have common underlying cognitive impairments and manifest as a continuum or spectrum of disorders (Reference SnowlingSnowling 2008).

The most common childhood psychiatric disorders reported in dyslexia are conduct disorder and attention-deficit hyperactivity disorder (ADHD). In the Isle of Wight study, one-third of the 10-year-olds with reading disability were reported to have conduct disorder and one-third with conduct disorder were shown to have reading disability (Reference Berger, Yule and RutterBerger 1975). A number of studies have reported a strong relationship between early reading disability and oppositional behaviour in pre-adolescence and conduct disorder in adolescence (Reference Carroll, Maughan and GoodmanCarroll 2005). The prevalence of dyslexia among youth offenders has been reported to be around 33% (Reference Williams and McGeeWilliams 1994). Comorbidity with ADHD is in the range of 40% (Reference Pennington, Olson, Snowling and HulmesPennington 2005). Genetic research shows that this may be due to shared genetic influence (Reference Willcutt and PenningtonWillcutt 2000). These and other findings have led to the inclusion of reading and literacy interventions in parent training programmes designed for children with behavioural problems. It should be noted that treatment of ADHD with medication seems to have no effect on reading in those with dyslexia and comorbid ADHD (Reference Willcutt and PenningtonWillcutt 2000).

Internalising disorders, especially anxiety, are particularly common in girls with dyslexia (Reference PenningtonPennington 2009: p. 48). Dyslexia in children may contribute to school refusal as their literacy problems can make school an unpleasant place (Reference Thambirajah, Grandison and De-HayesThambirajah 2008: p 36). A prominent feature of some children with dyslexia is fear of failure, resulting in avoidance of reading. Consequently, they fall further behind in reading. This has been called the Matthew effect in reading (a term borrowed from The New Testament to mean that the rich get richer and the poor get poorer; Reference StanovichStanovich, 1986). The psychological impact of the realisation that they have difficulties with reading can be devastating for children. It can result in chronic frustration, low self-esteem, anxiety and oppositional behaviour. These secondary effects of dyslexia may prompt referral to child and adolescent mental health services (CAMHS). Parents are often concerned about their child's academic underachievement.

Developmental history

The developmental history of most children with dyslexia is usually unremarkable, although mild speech delays are reported in some. Since dyslexia is a specific developmental disorder, it is generally accepted that development in other areas is normal. The most significant information is to be found embedded in the early development of reading and in educational history. A family history of reading difficulties is a good predictor of dyslexia in the child, but parents may not volunteer this information. Specific enquiries need to made about parents' reading difficulties.

During the pre-school period a history of delayed speech development in early childhood is a marker for dyslexia (Reference Shaywitz and ShaywitzShaywitz 2003a). One of the earliest indications of dyslexia is difficulty in learning names of objects, colours and letters of the alphabet and sounds of letters of the alphabet. Difficulty learning nursery rhymes, slow learning of letters, and difficulty remembering names of letters or failure to know the letters of one's own name are common. Reading problems commonly become noticeable during the first 2 years of schooling (usually at 5 to 6 years of age) and are most prominent during middle childhood (8 to 12 years of age). It is common for children to forget newly learned words because of poor consolidation of short-term phonological memory. Reading is often slow and laboured. As the child grows older, difficulties in copying from the board and poor spelling become common. Learning a second language is particularly difficult. In mathematics, many children show difficulties when numerical problems are presented in written form. In adolescence and adulthood, lack of fluent reading may be the most evident indicator. Slow, laboured reading is the hallmark of dyslexia in older readers. Poor performance on timed tests is common. Children with dyslexia begin to avoid reading from an early age and many show a prominent lack of enjoyment in reading.

Clinical examination

The three essential features of developmental dyslexia are inaccurate reading, poor spelling and slow reading.

Identifying dyslexia

Although most, if not all, children with dyslexia show the features listed in Box 2, the presentation, severity and the psychological profile of the disorder show considerable individual variation.

Identifying reading difficulties is usually straight-forward and does not necessarily involve extensive testing, especially in more severe cases. However, in CAMHS the immediacy of the presenting problems (e.g. severe conduct problems) may mask specific developmental disorders unless they are deliberately looked for. A three-step approach to identification is proposed here, which includes initial screening, followed by a more comprehensive assessment and, last and if appropriate, referral for further investigations using standardised psychometric tests.

Diagnosis

For a diagnosis of dyslexia to be made, the clinician must first establish that the severity of reading difficulty is significant and persistent. A reading age that is 2 years below the child's chronological age or a standard score 1–1.5 s.d. below the mean on reading tests is usually taken as the cut-off. Second, the clinician must be satisfied that the condition is idiopathic, i.e. that the poor performance in reading and spelling is not due to other identifiable causes.

Life course and prognosis

Well-designed longitudinal studies indicate that reading deficits seen in dyslexia are generally stable and persist into late adolescence and adulthood. Although both dyslexic and unimpaired readers improve their reading scores as they get older, the gap between the two groups remains. In the Connecticut Longitudinal Study, over 70% of those identified as having dyslexia in Grade 3 (about 8 years old) remained dyslexic as adults (Reference Shaywitz, Fletcher and HolahamShaywitz 1999, Reference Shaywitz2003b). Even with intensive evidence-based reading interventions, about half the children do not show substantial improvement (non-responders) (Reference Torgesen, Alaxander and WagnerTorgesen 2001). Initial severity of dyslexia and general intellectual level seem the most important predictors of later progress.

Viewed from a long-term perspective, dyslexia does not represent a transient lag in development; rather, the reading impairment is persistent, continuing into adolescence and adulthood, and most dyslexic readers do not ‘catch up’. Many young people with dyslexia develop compensatory reading strategies to circumvent their reading difficulties, but they continue to lag behind their peers, especially in spelling and reading speed. Spelling appears to be a major problem for adults with dyslexia. Follow-up of the reading-disabled Isle of Wight sample at 44 years of age shows that more than three-quarters showed significant problems with spelling (with spelling scores 2 s.d. below the mean) compared with peers (Reference Maughan, Nesser and CollishawMaughan 2009). Slow reading speed is typical of adults with dyslexia. Another consistent finding in research is that adults who were diagnosed with dyslexia in childhood continue to have impaired performance on phonological decoding tasks, indicating that the core cognitive deficits of dyslexia are persistent (Reference Vellutino, Fletcher and SnowlingVellutino 2004). There is little research on psychosocial adjustment in adults with dyslexia.

Clinical encounters

The following anonymised case histories are typical of children presenting to psychiatrists with problems related to dyslexia.

Interventions

Intervention studies in dyslexia may be grouped into two types: those aimed at early prevention of reading difficulties in young children and those that attempt to treat or remediate reading problems in older children. As mentioned before, dyslexia can be reliably identified in the first 2 years of schooling. Several well-designed studies (e.g. Reference Hatcher, Hulme and SnowlingHatcher 2004) have shown that reading interventions for the ‘at-risk’ population, such as Year 1 (6-year-old) children who are below the 15th to 20th percentile in reading attainment, produce substantial improvement. However, remediation programmes after the age of 8 or so, i.e. after the child starts to fail at reading, produce relatively poor results. Although the developmental trajectories of individual children vary, in general the gap in performance between average readers and readers with dyslexia tends to persist. In the older group, reading interventions seem merely to stabilise, rarely bringing about total remediation (Reference Torgesen, Snowling and HulmeTorgesen 2005).

There is now an impressive body of literature on the most evidence-based methods of intervention (i.e. ‘what works’) in dyslexia. However, often it is not reflected in practice. In the UK, the National Literacy Strategy sets out the principles and practice for teaching of reading to all children (Department for Education and Employment 1988). Children who fail to develop sufficient reading skills should be targeted for special reading instruction as outlined in the Early Literacy Support (ELS) programme (Department for Education and Skills 2001). The ELS programme is an intervention for Year 1 children whose reading skills are identified to be below the 25th percentile. They receive additional reading support from the class teacher and a trained teaching assistant. Many children could be expected to make significant progress in reading with ELS-type early interventions (Torgersen 2005). The ‘small minority’ of children who do not make sufficient progress with ELS (non-responders) receive (or should receive) more individualised interventions such as one-to-one reading programmes (Department for Children, Schools and Families 2010). Although official ELS documents do not specifically mention dyslexia or reading disability, it is highly probable that this ‘small minority’ would include most children with dyslexia. It is worth noting that children with dyslexia are usually taught in mainstream schools unless there is accompanying comorbidity such as moderate general intellectual disability or severe conduct problems.

In practice, severe reading difficulties are identified too late, typically not until Year 3 (at about 8 years of age). Although there are government guidelines on the assessment of reading difficulties in adults that indicate which psychometric tests should be used (Learning and Skills Improvement Service 2010), there are no rigorous protocols for assessment in children apart from curriculum-based assessments. This may partly account for the late identification of dyslexia in the UK.

The role of the child psychiatrist

Dyslexia is primarily a specific learning difficulty but child psychiatrists are bound to encounter it frequently in their work because of its high comorbidity with mental health problems. The condition is often overlooked. Moreover, it is not always identified by teachers before complications set in. Child psychiatrists should be able to identify dyslexia with confidence and draw the school's attention to a child's reading disability. It is important to have a good knowledge of national policies as well as those of local education authorities and to maintain good communication with schools and educational psychology services. Some practical hints for the management of dyslexia and comorbid psychiatric features in children are shown in Box 9.

Child psychiatrists also need to be aware of the widely different approaches adopted by different professional groups and services. In the case of dyslexia, health professionals talk of diagnosis and treatment, whereas educational professionals talk of identification and intervention (British Psychological Society 2005). Psychiatrists tend to subscribe to a ‘deficit theory’ of dyslexia, whereas others may subscribe to a ‘brain difference’ theory. Effective inter-agency working necessarily involves accommodating different perspectives and approaches.

MCQs

Select the single best option for each question stem

1. 1 Of the following groups of children and young people, dyslexia is least common among:

   1. a youth offenders

   2. b children with ADHD

   3. c children with speech and language impairment

   4. d adolescents with schizophrenia

   5. e children with significant motor clumsiness.

2. 2 Which of the following is not a useful clue in the identification of dyslexia?

   1. a a history of early speech and language problems

   2. b reading difficulties in the parent

   3. c difficulties in identifying letters during preschool period

   4. d problems in naming pictures and objects

   5. e letter reversals in a 5-year-old.

3. 3 Which of the following tests are useful in the identification of dyslexia?

   1. a sentence completion tests

   2. b sentence reading tests

   3. c reading comprehension tests

   4. d non-word reading tests

   5. e IQ tests (e.g. WISC).

4. 4 The following are not true of developmental dyslexia:

   1. a it can be identified by the age of 5 to 6 years

   2. b it is more common in children with ADHD

   3. c it is familial

   4. d the phonological problems continue into adulthood

   5. e it is more common in Spain and Italy than in the UK.

5. 5 In the management of dyslexia the primary role of the child psychiatrist is to:

   1. a persuade parents to demand special education for the child

   2. b treat the child with cognitive–behavioural therapy

   3. c treat comorbid child psychiatric conditions

   4. d refer the child to an optician for tinted glasses or overlays

   5. e ask an educational psychologist to see the child.

MCQ answers

1

d

2

e

3

d

4

e

5

c