Phonological characteristics of novel gesture production in children with developmental language disorder: Longitudinal findings

A systematic review of language and motor skills in children with developmental coordination disorder (DCD) and developmental language disorder (DLD)

AIM

To investigate: (a) language difficulties in children with developmental coordination disorder (DCD), and (b) motor difficulties in children with developmental language disorder (DLD).

METHOD

In this systematic review, PubMed, CINAHL, PsycINFO, and Embase were searched to identify peer-reviewed studies. Two researchers independently identified, screened and evaluated the methodological quality of the included studies following the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA). For objective (a), we combined the terms: "developmental coordination disorder" AND "language skills" AND "children". For objective (b) we combined the terms: "developmental language disorder" AND "motor skills" AND "children".

RESULTS

Ten studies on language skills in children with DCD and 34 studies on motor skills in children with DLD are included, most with relatively good methodological quality. The results for language comprehension and production in children with DCD are contradictory, but there is evidence that children with DCD have communication and phonological problems. Evidence for general motor problems in children with DLD is consistent. Studies report problems in balance, locomotor, and fine motor skills in children with DLD. Evidence for aiming and catching skills is inconsistent.

INTERPRETATION

The findings of this systematic review highlight the co-occurrence of language impairments in children with DCD and motor impairments in children with DLD. Healthcare professionals involved in the assessment and diagnosis of children with DCD or DLD should be attentive to this co-occurrence. In doing so, children with DCD and DLD can receive optimal interventions to minimize problems in their daily life.

Subcortical brain iron and its link to verbal memory in children with developmental language disorder

Developmental Language Disorder (DLD) is a common neurodevelopmental condition characterized by significant difficulty with language learning, comprehension, and expression. The neurocognitive bases of DLD are underspecified but are thought to be related, in part, to altered basal ganglia (BG). The BG are known to have a high level of brain iron, which contributes to myelination and dopaminergic pathways among other physiological mechanisms. In this study, we investigated whether a brain iron imbalance might contribute to the altered BG function that characterizes individuals with DLD. Using a T2*-weighted signal, we compared BG brain iron levels in 7-to-13-year olds with DLD and typical language development (TD). We found a significant age-by-group interaction in the caudate with children with DLD showing a positive association between brain iron and age, which was not the case in TD children. A sex-by-age-by-group interaction was also reported in the right putamen and right nucleus accumbens. Higher brain iron in the caudate was associated with poorer story recall; there was no relation between brain iron levels and recall of word lists. This first-ever investigation of brain iron levels in individuals with DLD provides preliminary evidence of an abnormal developmental trajectory of brain iron balance and offers a potential explanation for the altered BG function and verbal impairments that characterize DLD.

A developmental account of the role of sequential dependencies in typical and atypical language learners

The Gerken lab has shown that infants are able to learn sound patterns that obligate local sequential dependencies that are no longer readily accessible to adults. The Goffman lab has shown that children with developmental language disorder (DLD) exhibit deficits in learning sequential dependencies that influence the acquisition of words and grammar, as well as other types of domain general sequences. Thus, DLD appears to be an impaired ability to detect and deploy sequential dependencies over multiple domains. We meld these two lines of research to propose a novel account in which sequential dependency learning is required for many phonological and morphosyntactic patterns in natural language and is also central to the language and domain general deficits that are attested in DLD. However, patterns that are not dependent on sequential dependencies but rather on networks of stored forms are learnable by children with DLD as well as by adults.

Phonological and Articulatory Deficits in the Production of Novel Signs in Children With Developmental Language Disorder

PURPOSE

Sign language, like spoken language, incorporates phonological and articulatory (or motor) processing components. Thus, the learning of novel signs, like novel spoken word forms, may be problematic for children with developmental language disorder (DLD). In the present work, we hypothesize that phonological and articulatory deficits in novel sign repetition and learning would differentiate preschool-age children with DLD from their typical peers.

METHOD

Children with DLD (n = 34; aged 4-5 years) and their age-matched typical peers (n = 21) participated. Children were exposed to four novel signs, all iconic, but only two linked to a visual referent. Children imitatively produced these novel signs multiple times. We obtained measures of phonological accuracy and articulatory motion stability as well as of learning of the associated visual referent.

RESULTS

Children with DLD showed an increased number of phonological feature (i.e., handshape, path, and orientation of the hands) errors when compared with their typical peers. While articulatory variability did not overall differentiate children with DLD from typical peers, children with DLD showed instability in one novel sign that obligated bimanual oppositional movement. Semantic aspects of novel sign learning were unaffected in children with DLD.

CONCLUSIONS

Deficits that have been documented in phonological organization of spoken words in children with DLD are also evident in the manual domain. Analyses of hand motion variability suggest that children with DLD do not show a generalized motor deficit, but one that is restricted to the implementation of coordinated and sequential hand motion.