Meta-analysis and meta-regression were used to evaluate whether evidence to date demonstrates deficits in procedural memory in individuals with specific language impairment (SLI), and to examine ...reasons for inconsistencies of findings across studies. The Procedural Deficit Hypothesis (PDH) proposes that SLI is largely explained by abnormal functioning of the frontal-basal ganglia circuits that support procedural memory. It has also been suggested that declarative memory can compensate for at least some of the problems observed in individuals with SLI. A number of studies have used Serial Reaction Time (SRT) tasks to investigate procedural learning in SLI. In this report, results from eight studies that collectively examined 186 participants with SLI and 203 typically-developing peers were submitted to a meta-analysis. The average mean effect size was .328 (CI95: .071, .584) and was significant. This suggests SLI is associated with impairments of procedural learning as measured by the SRT task. Differences among individual study effect sizes, examined with meta-regression, indicated that smaller effect sizes were found in studies with older participants, and in studies that had a larger number of trials on the SRT task. The contributions of age and SRT task characteristics to learning are discussed with respect to impaired and compensatory neural mechanisms in SLI.
Aim
The neurobiological contributions of childhood language disorder are not well understood. Yet there is increasing evidence that language disorder is associated with differences in brain structure ...and/or function in core language regions. A key hypothesis has been that children with language disorder do not show the same degree of leftward asymmetry of these regions as observed in typically developing children. We aimed to systematically review structural and functional magnetic resonance imaging (fMRI) studies to examine brain commonalities and differences between children with language disorder and typically developing controls; and differences in leftward asymmetry between these groups.
Method
A systematic review was conducted using MeSH terms synonymous with childhood language disorder and brain MRI methods. The search identified 1443 papers, and 18 articles met the criteria and were appraised for level and quality of evidence.
Results
Atypical brain structure and function was reported within traditionally recognized language regions across studies, including the inferior frontal gyrus, posterior superior temporal gyrus, and caudate nucleus. The direction of difference (e.g. increased/decreased) was variable, however, likely because of differences in language disorder groups examined and magnetic resonance data acquisition and analysis approaches. As regards asymmetry, there was some evidence of reduction of the anticipated structural and functional leftward asymmetry in frontal language regions in language disorder groups.
Interpretation
Mounting evidence suggests that children with language disorder have atypical brain structure and function within neural regions integral to language. There is limited support for the hypothesis that children with language disorder show a reduction of leftward structural and/or functional asymmetry in frontal language regions. Interpretation is limited, however, by a high degree of variability in language disorder assessment and phenotype, and in magnetic resonance methodologies. A large‐scale magnetic resonance study of brain structure and function is required in a well‐defined language disorder population cohort, with replication, to provide confirmatory data on the neural correlates of childhood language disorder.
What this paper adds
Atypical brain structure and/or function consistently reported in key language‐related brain regions for language disorder groups.
High variability in language disorder phenotype and magnetic resonance approaches limits ability to draw robust conclusions regarding brain asymmetry.
Limited evidence to support reduced leftward structural and functional asymmetry in frontal language‐related brain regions in language disorder groups.
Aim
To examine the phenomenology of stuttering across the lifespan in the largest prospective cohort to date.
Method
Participants aged 7 years and older with a history of developmental stuttering ...were recruited. Self‐reported phenotypic data were collected online including stuttering symptomatology, co‐occurring phenotypes, genetic predisposition, factors associated with stuttering severity, and impact on anxiety, education, and employment.
Results
A total of 987 participants (852 adults: 590 males, 262 females, mean age 49 years SD = 17 years 10 months; range = 18–93 years and 135 children: 97 males, 38 females, mean age 11 years 4 months SD = 3 years; range = 7–17 years) were recruited. Stuttering onset occurred at age 3 to 6 years in 64.0%. Blocking (73.2%) was the most frequent phenotype; 75.9% had sought stuttering therapy and 15.5% identified as having recovered. Half (49.9%) reported a family history. There was a significant negative correlation with age for both stuttering frequency and severity in adults. Most were anxious due to stuttering (90.4%) and perceived stuttering as a barrier to education and employment outcomes (80.7%).
Interpretation
The frequent persistence of stuttering and the high proportion with a family history suggest that stuttering is a complex trait that does not often resolve, even with therapy. These data provide new insights into the phenotype and prognosis of stuttering, information that is critically needed to encourage the development of more effective speech therapies.
What this paper adds
Half of the study cohort had a family history of stuttering.
While 75.9% of participants had sought stuttering therapy, only 15.5% identified as having recovered.
There was a significant negative correlation between age and stuttering frequency and severity in adults.
What this paper adds
Half of the study cohort had a family history of stuttering.
While 75.9% of participants had sought stuttering therapy, only 15.5% identified as having recovered.
There was a significant negative correlation between age and stuttering frequency and severity in adults.
Little is understood about the phenotype or prognosis for stuttering at a population level. Here we examine stuttering in the largest prospective cohort to date. In total, 987 (852 adults, 135 children) participants were recruited; of which 75.9% had sought stuttering therapy; 15.5% identified as recovered. Half reported a family history. There was a negative correlation for stuttering frequency and severity over time. The persistence of stuttering and high proportion with a family history suggests stuttering is a complex trait which does not often resolve.
This original article is commented on by Herring and Yaruss on pages 1188–1189 of this issue.
Autism spectrum disorder (ASD) has an estimated prevalence of around 1.7% of the population. People with ASD often also have language difficulties, and about 25% to 30% of children with ASD either ...fail to develop functional language or are minimally verbal. The ability to communicate effectively is an essential life skill, and difficulties with communication can have a range of adverse outcomes, including poorer academic achievement, behavioural difficulties and reduced quality of life. Historically, most studies have investigated communication interventions for ASD in verbal children. We cannot assume the same interventions will work for minimally verbal children with ASD.
To assess the effects of communication interventions for ASD in minimally verbal children.
We searched CENTRAL, MEDLINE and Embase as well as 12 other databases and three trials registers in November 2017. We also checked the reference lists of all included studies and relevant reviews, contacting experts in the field as well as authors of identified studies about other potentially relevant ongoing and unpublished studies.
Randomised controlled trials (RCTs) of communication-focused interventions for children (under 12 years of age) diagnosed with ASD and who are minimally verbal (fewer than 30 functional words or unable to use speech alone to communicate), compared with no treatment, wait-list control or treatment as usual.
We used standard Cochrane methodological procedures.
This review includes two RCTs (154 children aged 32 months to 11 years) of communication interventions for ASD in minimally verbal children compared with a control group (treatment as usual). One RCT used a verbally based intervention (focused playtime intervention; FPI) administered by parents in the home, whereas the other used an alternative and augmentative communication (AAC) intervention (Picture Exchange Communication System; PECS) administered by teachers in a school setting.The FPI study took place in the USA and included 70 participants (64 boys) aged 32 to 82 months who were minimally verbal and had received a diagnosis of ASD. This intervention focused on developing coordinated toy play between child and parent. Participants received 12 in-home parent training sessions for 90 minutes per session for 12 weeks, and they were also invited to attend parent advocacy coaching sessions. This study was funded by the National Institute of Child Health and Human Development, the MIND Institute Research Program and a Professional Staff Congress-City University of New York grant. The PECS study included 84 minimally verbal participants (73 boys) aged 4 to 11 years who had a formal diagnosis of ASD and who were not using PECS beyond phase 1 at baseline. All children attended autism-specific classes or units, and most classes had a child to adult ratio of 2:1. Teachers and parents received PECS training (two-day workshop). PECS consultants also conducted six half-day consultations with each class once per month over five months. This study took place in the UK and was funded by the Three Guineas Trust.Both included studies had high or unclear risk of bias in at least four of the seven 'Risk of bias' categories, with a lack of blinding for participants and personnel being the most problematic area. Using the GRADE approach, we rated the overall quality of the evidence as very low due to risk of bias, imprecision (small sample sizes and wide confidence intervals) and because there was only one trial identified per type of intervention (i.e. verbally based or AAC).Both studies focused primarily on communication outcomes (verbal and non-verbal). One of the studies also collected information on social communication. The FPI study found no significant improvement in spoken communication, measured using the expressive language domain of the Mullen Scale of Early Learning expressive language, at postintervention. However, this study found that children with lower expressive language at baseline (less than 11.3 months age-equivalent) improved more than children with better expressive language and that the intervention produced expressive language gains in some children. The PECS study found that children enrolled in the AAC intervention were significantly more likely to use verbal initiations and PECS symbols immediately postintervention; however, gains were not maintained 10 months later. There was no evidence that AAC improved frequency of speech, verbal expressive vocabulary or children's social communication or pragmatic language immediately postintervention. Overall, neither of the interventions (PECS or FPI) resulted in maintained improvements in spoken or non-verbal communication in most children.Neither study collected information on adverse events, other communication skills, quality of life or behavioural outcomes.
There is limited evidence that verbally based and ACC interventions improve spoken and non-verbal communication in minimally verbal children with ASD. A substantial number of studies have investigated communication interventions for minimally verbal children with ASD, yet only two studies met inclusion criteria for this review, and we considered the overall quality of the evidence to be very low. In the study that used an AAC intervention, there were significant gains in frequency of PECS use and verbal and non-verbal initiations, but not in expressive vocabulary or social communication immediately postintervention. In the study that investigated a verbally based intervention, there were no significant gains in expressive language postintervention, but children with lower expressive language at the beginning of the study improved more than those with better expressive language at baseline. Neither study investigated adverse events, other communication skills, quality of life or behavioural outcomes. Future RCTs that compare two interventions and include a control group will allow us to better understand treatment effects in the context of spontaneous maturation and will allow further comparison of different interventions as well as the investigation of moderating factors.
Genetic investigations of people with impaired development of spoken language provide windows into key aspects of human biology. Over 15 years after FOXP2 was identified, most speech and language ...impairments remain unexplained at the molecular level. We sequenced whole genomes of nineteen unrelated individuals diagnosed with childhood apraxia of speech, a rare disorder enriched for causative mutations of large effect. Where DNA was available from unaffected parents, we discovered de novo mutations, implicating genes, including CHD3, SETD1A and WDR5. In other probands, we identified novel loss-of-function variants affecting KAT6A, SETBP1, ZFHX4, TNRC6B and MKL2, regulatory genes with links to neurodevelopment. Several of the new candidates interact with each other or with known speech-related genes. Moreover, they show significant clustering within a single co-expression module of genes highly expressed during early human brain development. This study highlights gene regulatory pathways in the developing brain that may contribute to acquisition of proficient speech.
Speech and language development are complex neurodevelopmental processes that are incompletely understood, yet current evidence suggests that speech and language disorders are prominent in those with ...disorders of chromatin regulation. This review aimed to unravel what is known about speech and language outcomes for individuals with chromatin-related neurodevelopmental disorders. A systematic literature search following PRISMA guidelines was conducted on 70 chromatin genes, to identify reports of speech/language outcomes across studies, including clinical reports, formal subjective measures, and standardised/objective measures. 3932 studies were identified and screened and 112 were systematically reviewed. Communication impairment was core across chromatin disorders, and specifically, chromatin writers and readers appear to play an important role in motor speech development. Identification of these relationships is important because chromatin disorders show promise as therapeutic targets due to the capacity for epigenetic modification. Further research is required using standardised and formal assessments to understand the nuanced speech/language profiles associated with variants in each gene, and the influence of chromatin dysregulation on the neurobiology of speech and language development.
•Speech/language disorders are universal in those with chromatin disorders.•Chromatin writers/readers may play an important role in motor speech development.•Many chromatin disorders lack systematic assessment of motor speech and/or language.•These links are key, as chromatin modifiers denote promising therapeutic targets.
Childhood apraxia of speech (CAS) is a rare disorder of childhood that can leave a watermark of the impacts throughout the lifetime. Since being first described in the 1950s, aetiological insights ...have been limited. At a neurobiological level, clinical MRI scans fail to reveal overt neural anomalies in individual cases with CAS, although quantitative MRI methods have revealed subtle brain anomalies at a group level. Dramatic insights, however, occurred in the past decade from the discovery of genetic pathways underlying the phenotype. Several single genes and copy number‐variant conditions are now associated with CAS either in relative isolation, as in the case of FOXP2 variants, or most typically in association with other neurodevelopmental conditions, such as epilepsy, intellectual disability, motor impairment and autism. CAS requires careful differential diagnosis from other childhood speech disorders, but when a severe and persistent diagnosis is confirmed, a genetic aetiology should increasingly be pursued.
Despite the growing use of control measures, environmental tobacco smoke (ETS) remains a significant pollutant source in indoor air in many areas of the world. Current control methods for reducing ...ETS exposure are inadequate to protect public health in environments where cigarettes are smoked. An alternative solution is botanical biofiltration which has previously been shown to lower concentrations of volatile organic compounds (VOCs) and particulate matter (PM) from a range of polluted air streams. This study is the first to assess the potential of a botanical biofilter with the species Spathiphyllum wallisii (Peace Lily) for the removal of cigarette-derived VOCs and all size fractions of PM. Single pass removal efficiencies of 43.26% for total VOCs and 34.37% for total suspended particles were achieved. The botanical biofilter reduced the concentrations of a range of harmful ETS chemicals including nicotine, limonene, and toluene. Evaluation of the re-emission of ETS constituents filtered by the botanical biofilter revealed no particle resuspension or off gassing. The results demonstrate the potential of botanical biofilters to reduce public ETS exposure, although further research is needed to improve upon and ensure the efficiency of these systems for practical applications.
Display omitted
•Active green walls filter a proportion of cigarette smoke.•Total volatile organic compound single pass removal efficiency was 43.26%.•Removal efficiency depends on type of volatile organic compound.•Total suspended particle single pass removal efficiency was 34.37%.•There was no post-filtration re-emission or re-suspension of cigarette smoke.
With increasing gene discoveries for severe speech disorders, genomic testing can alter the diagnostic and clinical paradigms, enabling better life outcomes for children and their families. However, ...evidence on the value of the outcomes generated is lacking, impeding optimal translation into health care. This study aims to estimate the value and uptake of genomic testing for severe childhood speech disorders. A discrete choice experiment was undertaken to elicit preferences for genomic testing from the perspective of the Australian public (n = 951) and parents of children experiencing severe speech disorder (n = 56). Choice attributes associated with genomic testing were identified through focus groups. A Bayesian D-efficient design was used to develop choice scenarios and choice data were analyzed using a panel error component mixed logit model and a latent class model. Statistically significant preferences were identified across all seven attributes. The mean monetary value of the benefits of genomic testing relative to standard diagnostic care in Australia was estimated at AU$7489 (US$5021) and AU$4452 (US$2985) from the perspectives of the Australian public and families with lived experience of severe speech disorders, with a corresponding test uptake of 94.2% and 99.6%. To ensure fair prioritization of genomics, decision-makers need to consider the wide range of risks and benefits associated with genomic information.
Pathogenic KAT6A variants cause syndromic neurodevelopmental disability. “Speech delay” is reported, yet none have examined specific speech and language features of KAT6A syndrome. Here we phenotype ...the communication profile of individuals with pathogenic KAT6A variants. Medical and communication data were acquired via standardized surveys and telehealth‐assessment. Forty‐nine individuals (25 females; aged 1;5–31;10) were recruited, most with truncating variants (44/49). Intellectual disability/developmental delay (42/45) was common, mostly moderate/severe, alongside concerns about vision (37/48), gastrointestinal function (33/48), and sleep (31/48). One‐third (10/31) had a diagnosis of autism. Seventy‐three percent (36/49) were minimally‐verbal, relying on nonverbal behaviors to communicate. Verbal participants (13/49) displayed complex and co‐occurring speech diagnoses regarding the perception/production of speech sounds, including phonological impairment (i.e., linguistic deficits) and speech apraxia (i.e., motor planning/programming deficits), which significantly impacted intelligibility. Receptive/expressive language and adaptive functioning were also severely impaired. Truncating variants in the last two exons of KAT6A were associated with poorer communication, daily‐living skills, and socialization outcomes. In conclusion, severe communication difficulties are present in KAT6A syndrome, typically on a background of significant intellectual disability, vision, feeding and motor deficits, and autism in some. Most are minimally‐verbal, with apparent contributions from underlying motor deficits and cognitive‐linguistic impairment. Alternative/augmentative communication (AAC) approaches are required for many into adult life. Tailored AAC options should be fostered early, to accommodate the best communication outcomes.
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