Is the Age of Developmental Milestones a Predictor for Future Development in Down Syndrome?

Pleiotropic effects of trisomy and pharmacologic modulation on structural, functional, molecular, and genetic systems in a Down syndrome mouse model

Down syndrome (DS) is characterized by skeletal and brain structural malformations, cognitive impairment, altered hippocampal metabolite concentration and gene expression imbalance. These alterations were usually investigated separately, and the potential rescuing effects of green tea extracts enriched in epigallocatechin-3-gallate (GTE-EGCG) provided disparate results due to different experimental conditions. We overcame these limitations by conducting the first longitudinal controlled experiment evaluating genotype and GTE-EGCG prenatal chronic treatment effects before and after treatment discontinuation. Our findings revealed that the Ts65Dn mouse model reflected the pleiotropic nature of DS, exhibiting brachycephalic skull, ventriculomegaly, neurodevelopmental delay, hyperactivity, and impaired memory robustness with altered hippocampal metabolite concentration and gene expression. GTE-EGCG treatment modulated most systems simultaneously but did not rescue DS phenotypes. On the contrary, the treatment exacerbated trisomic phenotypes including body weight, tibia microarchitecture, neurodevelopment, adult cognition, and metabolite concentration, not supporting the therapeutic use of GTE-EGCG as a prenatal chronic treatment. Our results highlight the importance of longitudinal experiments assessing the co-modulation of multiple systems throughout development when characterizing preclinical models in complex disorders and evaluating the pleiotropic effects and general safety of pharmacological treatments.

Cross-sectional developmental trajectories in the adaptive functioning of children and adolescents with Down syndrome

BACKGROUND

Persons with Down syndrome (DS) reveal adaptive functioning (AF) difficulties. Studies on AF in DS have focused mainly on describing the profile (i.e., strengths in socialization, and weaknesses in communication), while less is known about age-related differences. This study aimed to elucidate how AF changes with age in children and adolescents with DS, taking a cross-sectional developmental trajectory approach. Moreover, the contribution of both chronological age (CA) and mental age (MA) on AF development was explored.

METHOD

This study involved 115 children and adolescents (between 3 and 16 years old) with DS. Parents were interviewed about their children's AF on communication, daily living and socialization skills. Children and adolescents with DS were assessed on their developmental level.

RESULTS

While participants' standard scores on AF decreased linearly over time, their age-equivalent scores increased with linear or segmented patterns, depending on the skill considered. CA and MA were related to daily living skills and socialization to much the same degree, while MA correlated more strongly than CA with communication.

CONCLUSION

This study contributes to the understanding of how AF develops in children and adolescents with DS, showing that CA and MA both contribute to shaping the skills involved.

Vocal Characteristics of Infants at Risk for Speech Motor Involvement: A Scoping Review

PURPOSE

The purpose of this scoping review was to (a) summarize methodological characteristics of studies examining vocal characteristics of infants at high risk for neurological speech motor involvement and (b) report the state of the high-quality evidence on vocal characteristic trends of infants diagnosed or at high risk for cerebral palsy (CP).

METHOD

The PRISMA (Preferred Reporting Items of Systematic Reviews and Meta-Analyses) extension for scoping reviews was followed for reporting our review. Studies measured prelinguistic vocal characteristics of infants under 24 months with birth risk or genetic conditions known to commonly present with speech motor involvement. Fifty-five studies met criteria for Part 1. Eleven studies met criteria for synthesis in Part 2.

RESULTS

A smaller percentage of studies examined infants with or at risk for CP compared to studies examining genetic conditions such as Down syndrome. The median year of publication was 1999, with a median sample size of nine participants. Most studies were conducted in laboratory settings and used human coding of vocalizations produced during caregiver-child interactions. Substantial methodological differences were noted across all studies. A small number of high-quality studies of infants with or at risk for CP revealed high rates of marginal babbling, low rates of canonical babbling, and limited consonant diversity under 24 months. Mixed findings were noted across studies of general birth risk factors.

CONCLUSIONS

There is limited evidence available to support the early detection of speech motor involvement. Large methodological differences currently impact the ability to synthesize findings across studies. There is a critical need to conduct longitudinal research with larger sample sizes and advanced, modern technologies to detect vocal precursors of speech impairment to support the accurate diagnosis and prognosis of speech development in infants with CP and other clinical populations.

A call for obesity prevention interventions for young children with intellectual and developmental disabilities

Health disparities among children with intellectual and developmental disabilities (IDD) are present in early childhood. Yet, this population is underrepresented in health behavior research. In this commentary the authors highlight the need for multi-level physical activity and nutrition research for obesity prevention with a specific focus on young children with Down syndrome, a population at greater risk of developing overweight and obesity compared to typically developing peers. This commentary describes the comorbidities and developmental challenges faced by many children with Down syndrome which may influence weight-related physical activity and nutrition behaviors. Additionally, the authors advocate for involving a multidisciplinary team of experts to inform the adaptation or development of multi-level, theory-driven behavioral interventions to prevent obesity among children with Down syndrome.

Motor-language links in children with Down syndrome: a scoping review to revisit the literature with a developmental cascades lens

Background

Children with Down syndrome (DS) typically have motor and language needs. Improving function is a shared goal for the rehabilitation therapy team, however physical therapy, occupational therapy, and speech-language pathology professionals treat patients differently. This difference in care may mask developmental cascades whereby changes in one domain (e.g., motor) can have seemingly unexpected effects on another domain (e.g., language).

Objective

This scoping review identified papers where motor and language data have been reported together in children with DS and reinterpreted findings from a developmental cascades lens.

Design

Online databases were used to identify 413 papers published before October 2021 from which 33 papers were retained that reported both motor (gross and/or fine) and language (expressive and/or receptive) data in individuals with DS with a chronological age of 0-18 years.

Results

The majority of papers (79%) that reported motor and language data in children with DS did not examine their link, while 12% analyzed motor-language links, but using a cross-sectional or retrospective design. Only three papers (9%) utilized a longitudinal design to examine predictive links.

Conclusion

Motor functioning and language functioning have often been reported together, but not analyzed together, in studies of children with DS. The few studies that did analyze motor-language links largely replicated findings from other developmental populations where motor gains were positively linked to language gains. Analyzing links between domains when such data is available is needed to fully characterize developmental cascades in DS and may have broad clinical implications.

Machine learning based analysis for intellectual disability in Down syndrome

Down syndrome (DS) or trisomy 21 is the most common genetic cause of intellectual disability (ID), but a pathogenic mechanism has not been identified yet. Studying a complex and not monogenic condition such as DS, a clear correlation between cause and effect might be difficult to find through classical analysis methods, thus different approaches need to be used. The increased availability of big data has made the use of artificial intelligence (AI) and in particular machine learning (ML) in the medical field possible. The purpose of this work is the application of ML techniques to provide an analysis of clinical records obtained from subjects with DS and study their association with ID. We have applied two tree-based ML models (random forest and gradient boosting machine) to the research question: how to identify key features likely associated with ID in DS. We analyzed 109 features (or variables) in 106 DS subjects. The outcome of the analysis was the age equivalent (AE) score as indicator of intellectual functioning, impaired in ID. We applied several methods to configure the models: feature selection through Boruta framework to minimize random correlation; data augmentation to overcome the issue of a small dataset; age effect mitigation to take into account the chronological age of the subjects. The results show that ML algorithms can be applied with good accuracy to identify variables likely involved in cognitive impairment in DS. In particular, we show how random forest and gradient boosting machine produce results with low error (MSE <0.12) and an acceptable R2 (0.70 and 0.93). Interestingly, the ranking of the variables point to several features of interest related to hearing, gastrointestinal alterations, thyroid state, immune system and vitamin B12 that can be considered with particular attention for improving care pathways for people with DS. In conclusion, ML-based model may assist researchers in identifying key features likely correlated with ID in DS, and ultimately, may improve research efforts focused on the identification of possible therapeutic targets and new care pathways. We believe this study can be the basis for further testing/validating of our algorithms with multiple and larger datasets.

Individual and cumulative risk factors in developmental language disorder: A case-control study

Many mental disorders (MD) share common etiology, fuelling debates about the specificity of clinical categories and whether the presence of specific risk factors (RF) can distinguish among them. The study of developmental language disorder (DLD), more specifically, has been further hindered by a lack of consensus regarding its definition. These limitations increase the risk of under-detection and lifelong consequences for affected children. This paper aims (1) to document which individual RF allow differentiating DLD from other MD and (2) to compare the cumulative RF between children with DLD versus other MD. This case-control design study used medical records of a psychiatric sample of 795 preschoolers (mean age 4:11, 75% boys). A logistic regression measured the predictive value of potential RF on DLD. Later first sentences, maternal immigration and family history of language delay were identified as significant in explaining 30% of the variance for DLD diagnosis. An ANCOVA revealed that children with DLD were exposed to a significantly higher number of RF than were children with other MD. Public health policies informed with the knowledge of specific RF associated with DLD, and their cumulative impact, could improve early detection and reduce the cascade of negative consequences associated with DLD.

Impact of Neonatal Body (Dis)Proportionality Determined by the Cephalization Index (CI) on Gross Motor Development in Children with Down Syndrome: A Prospective Cohort Study

Background: Children with Down syndrome (DS) lag behind typical children in the acquisition of developmental milestones, which could differ depending on body proportionality. We aimed to determine the difference in the acquisition of developmental milestones in children with DS with a disproportionate cephalization index (CI) compared to a proportionate CI. We created a motor development model that predicted milestone acquisition times. Methods: In this 20-year prospective cohort study, 47 children with DS aged 3 months to 5 years, followed up to 2020, were grouped according to the ratio of head circumference to birth weight (HC/BW) or CI into proportionate (CI < 1.1) and disproportionate (CI ≥ 1.1). We used a modified Munich Functional Developmental Diagnostic Scale that was assessed for reliability and content validity (Levene’s test and discriminant analysis) to determine 28 motor milestones. Linear regression was used to predict time to milestone acquisition, controlling for sex, maternal age, and birth weight. Results: Compared to proportionate CI, children with disproportionate CI were delayed in the milestone acquisition of a prone position by 2.81 months, standing before walking by 1.29 months, and a supine position by 1.61 months. Both groups required more time to reach standing after the acquisition of independent walking, but children with disproportionate CI reached those milestones later (4.50 vs. 4.09 months, p < 0.001). Conclusion: Children with disproportionate CI acquired milestones in a predictable order but slower than those with a proportionate CI. Our findings support the need to classify the degree of motor developmental delay in children with DS into unique functional groups rather than rely on clinicians’ arbitrary descriptions of the timing of developmental delays in children with DS.

Early predictors of language outcomes in Down syndrome: A mini-review

As children with Down syndrome (DS) typically manifest significant delays in language development, the research has pointed out the predictors of later language skills for this clinical population. The purpose of this study was to systematically explore the evidence for early predictors of language outcomes in infants and toddlers with DS from studies published between 2012 and 2022. After the search, nine studies met the inclusion criteria. The results indicated that maternal educational level, adaptive level of functioning, cognitive function, attention skills, communicative intent of the child, early vocalizations, gestures, baby signs, parents' translation of their children's gestures into words, and vocabulary level are significant predictors of language outcomes in children with DS. These findings provide a timely and warranted summary of published work that contributes to current understanding of the development of language and communication in DS. They are therefore useful to researchers, clinicians, and families.

A reassessment of Jackson's checklist and identification of two Down syndrome sub-phenotypes

Down syndrome (DS) is characterised by several clinical features including intellectual disability (ID) and craniofacial dysmorphisms. In 1976, Jackson and coll. identified a checklist of signs for clinical diagnosis of DS; the utility of these checklists in improving the accuracy of clinical diagnosis has been recently reaffirmed, but they have rarely been revised. The purpose of this work is to reassess the characteristic phenotypic signs and their frequencies in 233 DS subjects, following Jackson's checklist. 63.77% of the subjects showed more than 12 signs while none showed less than 5, confirming the effectiveness of Jackson's checklist for the clinical diagnosis of DS. An association between three phenotypic signs emerged, allowing us to distinguish two sub-phenotypes: Brachycephaly, short and broad Hands, short Neck (BHN), which is more frequent, and "non-BHN". The strong association of these signs might be interpreted in the context of the growth defects observed in DS children suggesting decreased cell proliferation. Lastly, cognitive assessments were investigated for 114 subjects. The lack of association between the presence of a physical sign or the number of signs present in a subject and cognitive skills disproves the stereotype that physical characteristics are predictive of degree of ID.

Cognitive profiles in children and adolescents with Down syndrome

The Down syndrome (DS) phenotype is usually characterized by relative strengths in non-verbal skills and deficits in verbal processing, but high interindividual variability has been registered in the syndrome. The goal of this study was to explore the cognitive profile, considering verbal and non-verbal intelligence, of children and adolescents with DS, also taking into account interindividual variability. We particularly aimed to investigate whether this variability means that we should envisage more than one cognitive profile in this population. The correlation between cognitive profile and medical conditions, parents’ education levels and developmental milestones was also explored. Seventy-two children/adolescents with DS, aged 7–16 years, were assessed with the Wechsler Preschool and Primary Scale of Intelligence-III. Age-equivalent scores were adopted, and Verbal and Non-Verbal indices were obtained for each individual. The cognitive profile of the group as a whole was characterized by similar scores in the verbal and non-verbal domain. Cluster analysis revealed three different profiles, however: one group, with the lowest scores, had the typical profile associated with DS (with higher non-verbal than verbal intelligence); one, with intermediate scores, had greater verbal than non-verbal intelligence; and one, with the highest scores, fared equally well in the verbal and non-verbal domain. Three cognitive profiles emerged, suggesting that educational support for children and adolescents with DS may need to be more specific.

Development of Down Syndrome Research Over the Last Decades-What Healthcare and Education Professionals Need to Know

Down syndrome (DS) is the most prevalent neurodevelopmental disorder, with a known genetic cause. Besides facial dysmorphologies and congenital and/or acquired medical conditions, the syndrome is characterized by intellectual disability, accelerated aging, and an increased likelihood of an early onset Alzheimer's disease in adulthood. These common patterns of DS are derived from the long-held standard in the field of DS research, that describes individuals with DS as a homogeneous group and compares phenotypic outcomes with either neurotypical controls or other neurodevelopmental disorders. This traditional view has changed, as modern research pinpoints a broad variability in both the occurrence and severity of symptoms across DS, arguing for DS heterogeneity and against a single "DS profile." Nevertheless, prenatal counseling does not often prioritize the awareness of potential within-group variations of DS, portraying only a vague picture of the developmental outcomes of children with DS to expectant parents. This mini-review provides a concise update on existent information about the heterogeneity of DS from a full-spectrum developmental perspective, within an interdisciplinary context. Knowledge on DS heterogeneity will not only enable professionals to enhance the quality of prenatal counseling, but also help parents to set targeted early interventions, to further optimize daily functions and the quality of life of their children.