Dorothy V. M. Bishop

Developmental Dyslexia and Specific Language Impairment: Same or Different?

Developmental dyslexia and specific language impairment (SLI) were for many years treated as distinct disorders but are now often regarded as different manifestations of the same underlying problem, differing only in severity or developmental stage. The merging of these categories has been motivated by the reconceptualization of dyslexia as a language disorder in which phonological processing is deficient. The authors argue that this focus underestimates the independent influence of semantic and syntactic deficits, which are widespread in SLI and which affect reading comprehension and impair attainment of fluent reading in adolescence. The authors suggest that 2 dimensions of impairment are needed to conceptualize the relationship between these disorders and to capture phenotypic features that are important for identifying neurobiologically and etiologically coherent subgroups.

Evidence from Turner's syndrome of an imprinted X-linked locus affecting cognitive function

Turners syndrome is a sporadic disorder of human females in which all or part of one X chromosome is deleted. Intelligence is usually normal but social adjustment problems are common. Here we report a study of 80 females with Turners syndrome and a single X chromosome, in 55 of which the X was maternally derived (45,Xm) and in 25 it was of paternal origin (45,Xp). Members of the 45,Xp group were significantly better adjusted, with superior verbal and higher-order executive function skills, which mediate social interactions. Our observations suggest that there is a genetic locus for social cognition, which is imprinted and is not expressed from the maternally derived X chromosome. Neuropsychological and molecular investigations of eight females with partial deletions of the short arm of the X chromosome indicate that the putative imprinted locus escapes X-inactivation, and probably lies on Xq or close to the centromere on Xp. If expressed only from the X chromosome of paternal origin, the existence of this locus could explain why 46,XY males (whose single X chromosome is maternal) are more vulnerable to developmental disorders of language and social cognition, such as autism, than are 46,XX females.

Development of the Children's Communication Checklist (CCC): a method for assessing qualitative aspects of communicative impairment in children.

The Childrens Communication Checklist (CCC) was developed to assess aspects of communicative impairment that are not adequately evaluated by contemporary standardised language tests. These are predominantly pragmatic abnormalities seen in social communication, although other qualitative aspects of speech and language were also included. Some items covering social relationships and restricted interests were incorporated, so that the relationship between pragmatic difficulties and other characteristics of pervasive developmental disorders could be explored. Checklist ratings were obtained for 76 children aged 7 to 9 years, all of whom had received special education for language impairment. In 71 cases, 2 raters (usually a teacher and speech-language therapist) independently completed the checklist, making it possible to establish inter-rater reliability. From an initial pool of 93 items, 70 items, grouped into 9 scales, were retained. Five of the subscales were concerned with pragmatic aspects of communication. A composite pragmatic impairment scale formed from these subscales had inter-rater reliability and internal consistency of around .80. This composite discriminated between children with a school diagnosis of semantic-pragmatic disorder and those with other types of specific language impairment (SLI). The majority of children with pragmatic language impairments did not have any evidence of restricted interests or significant difficulties in the domains of social relationships.

Is preschool language impairment a risk factor for dyslexia in adolescence

The literacy skills of 56 school leavers from the Bishop and Edmundson (1987) cohort of preschoolers with specific language impairment (SLI) were assessed at 15 years. The SLI group performed worse on tests of reading, spelling, and reading comprehension than age-matched controls and the literacy outcomes were particularly poor for those with Performance IQ less than 100. The rate of specific reading retardation in the SLI group had increased between the ages of 8 1/2 and 15 years and there had been a substantial drop in reading accuracy, relative to age. However, over 35% had reading skills within the normal range and those who had had isolated impairments of expressive phonology had a particularly good outcome. Our findings highlight the limitations of discrepancy definitions of dyslexia that do not take account of the changing demands of reading over time. We argue that childrens phonological difficulties place them at risk of literacy failure at the outset of reading and that later, impairments of other language skills compromise development to adult levels of fluency.

Exploring the borderlands of autistic disorder and specific language impairment: a study using standardised diagnostic instruments

BACKGROUND Two studies were conducted to test claims that pragmatic language impairment (PLI - previously referred to as semantic-pragmatic disorder) is simply another term for autistic disorder or pervasive developmental disorder not otherwise specified (PDDNOS). METHOD In Study 1, 21 children aged from 6 to 9 years with language impairments were subdivided on the basis of the Childrens Communication Checklist into 13 cases of pragmatic language impairment (PLI) and eight cases of typical specific language impairment (SLI-T). Parents completed the Autism Diagnostic Interview - Revised (ADI-R) and the Social Communication Questionnaire (SCQ), and the children were given the Autism Diagnostic Observation Schedule - Generic (ADOS-G). In Study 2, a further 11 children with SLI-T and 18 with PLI were assessed using the SCQ and ADOS-G. In addition, six children diagnosed with high-functioning autism and 18 normally developing children were assessed. RESULTS There was good agreement between ADI-R and SCQ diagnoses, but poor agreement between diagnoses based on these parental report measures and those based on ADOS-G. In many children, symptom profiles changed with age. Four PLI children from Study 1 and one from Study 2 met criteria for autistic disorder on both parental report (ADI-R or SCQ) and ADOS-G. Many of the others showed some autistic features, but there was a subset of children with pragmatic difficulties who were not diagnosed as having autism or PDDNOS by either instrument. These children tended to use stereotyped language with abnormal intonation/prosody, but they appeared sociable and communicative, had normal nonverbal communication, and showed few abnormalities outside the language/social communication domains. CONCLUSIONS Presence of pragmatic difficulties in a child with communication problems should prompt the clinician to evaluate autistic symptomatology, but it is dangerous to assume that all children with pragmatic difficulties have autism or PDDNOS.

Genetic basis of specific language impairment: Evidence from a twin study.

Concordance rates were compared for 63 monozygotic (MZ) and 27 dizygotic (DZ) same‐sex twin pairs, aged seven years and over, selected because at least one twin met diagnostic criteria for specific speech or language impairment. There was significant heritability for developmental speech and language disorder, defined according to DSM‐III‐R criteria. When the definition of the phenotype was broadened to include those with a past history of disorder and those with a less pronounced discrepancy between verbal and non‐verbal ability, concordance for MZ twins was close to 100 per cent, and that for DZ twins approximately 50 per cent. There was also close similarity between concordant twins for type of disorder. There is good evidence that genetic factors play a role in the aetiology of speech and language impairment; twin data may help us arrive at a clearer conception of the phenotype as well as quantifying the extent of the genetic contribution.

Narrative skills of children with communication impairments

BACKGROUND Narrative assessment is sensitive to the communication impairments of children with specific language impairment and those with autistic spectrum disorders. Although both groups of children tend to show deficits in narrative, it is unclear whether these deficits are qualitatively different and how language and pragmatic ability may impact on narrative competence. Comparing these two groups of children with children who exhibit pragmatic language impairment without autism may help to clarify these issues. AIMS This study explored the relationship between structural language ability and pragmatic competence in narrative in children with communication impairments and typically developing children. METHODS AND PROCEDURES Diagnostic status was determined using the Childrens Communication Checklist. All children were asked to generate a narrative to the wordless picture book Frog, Where are You? (Mayer 1969). Narratives were analysed according to their global structure, local linguistic structure and the childs ability to provide evaluative comments, especially about mental or emotional states. OUTCOMES AND RESULTS No group differences were seen in global structure or evaluation. Children with specific language impairment and autistic disorder made more syntactic errors, and children with autism were significantly more likely to provide ambiguous references in the story. No significant relationships were evident between the Childrens Communication Checklist and narrative measures. The complexity of language used was related to evaluation in the clinical groups. CONCLUSIONS Narrative is a good way of assessing linguistic ability in older children with communication impairments. Core language abilities rather than pragmatic skill or diagnostic status are likely to influence narrative development.

Phonological Processing, Language, and Literacy: A Comparison of Children with Mild-to-moderate Sensorineural Hearing Loss and Those with Specific Language Impairment

Phonological skills, language ability, and literacy scores were compared for four groups: 19 children with mild-to-moderate sensorineural hearing loss (SNH), 20 children with specific language impairment (SLI), 20 controls matched on chronological age to the SNH group (CA), and 15 controls matched on receptive vocabulary level to a subset of the SLI group (CB). In common with the SLI group, mean scores of children with mild-to-moderate hearing loss were significantly poorer on tests of phonological short-term memory, phonological discrimination, and phonological awareness than CA controls. No differences between group means were observed in SNH and CA control groups on vocabulary, digit and sentence recall, sentence comprehension, and literacy scores. However, there was considerable individual variation within the SNH group. Nearly 50% of the SNH group showed phonological impairment associated with poorer expressive and receptive vocabulary and higher hearing thresholds than remaining children without phonological impairment. Nonword repetition deficits were observed in SNH subgroups with and without phonological impairment and were of a similar magnitude to those observed in children with SLI. Indeed, poorer repetition in children with SLI could only be differentiated from children with SNH on phonologically complex nonwords. Overall, findings suggested major problems in nonword repetition and phonological impairment occurred without clinically significant deficits in wider language and literacy abilities in children with mild-to-moderate sensorineural hearing loss. Implications for theories of SLI are discussed.

Relations Among Speech, Language, and Reading Disorders

In this article, we critically review the evidence for overlap among three developmental disorders, namely speech sound disorder (SSD), language impairment (LI), and reading disability (RD), at three levels of analysis: diagnostic, cognitive, and etiological. We find that while overlap exists at all three levels, it varies by comorbidity subtype, and the relations among these three disorders are complex and not fully understood. We evaluate which comorbidity models can be rejected or supported as explanations for why and how these three disorders overlap and what new data are needed to better define their relations.

A manifesto for reproducible science

Improving the reliability and efficiency of scientific research will increase the credibility of the published scientific literature and accelerate discovery. Here we argue for the adoption of measures to optimize key elements of the scientific process: methods, reporting and dissemination, reproducibility, evaluation and incentives. There is some evidence from both simulations and empirical studies supporting the likely effectiveness of these measures, but their broad adoption by researchers, institutions, funders and journals will require iterative evaluation and improvement. We discuss the goals of these measures, and how they can be implemented, in the hope that this will facilitate action toward improving the transparency, reproducibility and efficiency of scientific research.