Motor Development and Neuropsychological Patterns in Persons with Down Syndrome

Variegated overexpression of chromosome 21 genes reveals molecular and immune subtypes of Down syndrome

Individuals with Down syndrome, the genetic condition caused by trisomy 21, exhibit strong inter-individual variability in terms of developmental phenotypes and diagnosis of co-occurring conditions. The mechanisms underlying this variable developmental and clinical presentation await elucidation. We report an investigation of human chromosome 21 gene overexpression in hundreds of research participants with Down syndrome, which led to the identification of two major subsets of co-expressed genes. Using clustering analyses, we identified three main molecular subtypes of trisomy 21, based on differential overexpression patterns of chromosome 21 genes. We subsequently performed multiomics comparative analyses among subtypes using whole blood transcriptomes, plasma proteomes and metabolomes, and immune cell profiles. These efforts revealed strong heterogeneity in dysregulation of key pathophysiological processes across the three subtypes, underscored by differential multiomics signatures related to inflammation, immunity, cell growth and proliferation, and metabolism. We also observed distinct patterns of immune cell changes across subtypes. These findings provide insights into the molecular heterogeneity of trisomy 21 and lay the foundation for the development of personalized medicine approaches for the clinical management of Down syndrome.

Developmental Profile in Children Aged 3-6 Years: Down Syndrome vs. Autism Spectrum Disorder

This research aims to compare the developmental profiles of children with autism spectrum disorder (ASD) and children with Down Syndrome (DS) between the ages of 3 and 6 years. The study examines whether these developmental disorders share common developmental milestones or exhibit distinctive characteristics. A total of 43 children, 23 with DS and 20 with ASD, participated in the study. Cognitive and language skills were assessed using standardized tools, including the Battelle Developmental Inventory, Reynell Developmental Language Scales III, and NEPSY-II battery. The results indicated that children with ASD outperformed children with DS in the areas of fine motor skills, gross motor skills, and communication. Additionally, children with ASD demonstrated higher scores in language comprehension and expressive language, compared to children with DS. Significant correlations were found between motor skills and communication abilities. Neuropsychological evaluations revealed significant differences between the two groups in various tasks, such as the comprehension of instructions, body part naming and identification, and recognition of emotions. These findings contribute to our understanding of the similarities and differences between ASD and DS, shedding light on the dissociation between cognition and language and its impact on adaptive functioning in these populations.

Sensory experiences questionnaire unravels differences in sensory profiles between MECP2-related disorders

The methyl CpG-binding protein-2 (MECP2) gene is located on the Xq28 region. Loss of function mutations or increased copies of MECP2 result in Rett syndrome (RTT) and MECP2 duplication syndrome (MDS), respectively. Individuals with both disorders exhibit overlapping autism symptoms, yet few studies have dissected the differences between these gene dosage sensitive disorders. Further, research examining sensory processing patterns in persons with RTT and MDS is largely absent. Thus, the goal of this study was to analyze and compare sensory processing patterns in persons with RTT and MDS. Towards this goal, caregivers of 50 female individuals with RTT and 122 male individuals with MDS, between 1 and 46 years of age, completed a standardized measure of sensory processing, the Sensory Experiences Questionnaire. Patterns detected in both disorders were compared against each other and against normative values. We found sensory processing abnormalities for both hyper- and hypo-sensitivity in both groups. Interestingly, abnormalities in MDS were more pronounced compared with in RTT, particularly with items concerning hypersensitivity and sensory seeking, but not hyposensitivity. Individuals with MDS also exhibited greater sensory symptoms compared with RTT in the areas of tactile and vestibular sensory processing and for both social and nonsocial stimuli. This study provides a first description of sensory symptoms in individuals with RTT and individuals with MDS. Similar to other neurodevelopmental disorders, a variety of sensory processing abnormalities was found. These findings reveal a first insight into sensory processing abnormalities caused by a dosage sensitive gene and may ultimately help guide therapeutic approaches for these disorders.

The Variegation of Human Brain Vulnerability to Rare Genetic Disorders and Convergence With Behaviorally Defined Disorders

BACKGROUND

Diverse gene dosage disorders (GDDs) increase risk for psychiatric impairment, but characterization of GDD effects on the human brain has so far been piecemeal, with few simultaneous analyses of multiple brain features across different GDDs.

METHODS

Here, through multimodal neuroimaging of 3 aneuploidy syndromes (XXY [total n = 191, 92 control participants], XYY [total n = 81, 47 control participants], and trisomy 21 [total n = 69, 41 control participants]), we systematically mapped the effects of supernumerary X, Y, and chromosome 21 dosage across a breadth of 15 different macrostructural, microstructural, and functional imaging-derived phenotypes (IDPs).

RESULTS

The results revealed considerable diversity in cortical changes across GDDs and IDPs. This variegation of IDP change underlines the limitations of studying GDD effects unimodally. Integration across all IDP change maps revealed highly distinct architectures of cortical change in each GDD along with partial coalescence onto a common spatial axis of cortical vulnerability that is evident in all 3 GDDs. This common axis shows strong alignment with shared cortical changes in behaviorally defined psychiatric disorders and is enriched for specific molecular and cellular signatures.

CONCLUSIONS

Use of multimodal neuroimaging data in 3 aneuploidies indicates that different GDDs impose unique fingerprints of change in the human brain that differ widely depending on the imaging modality that is being considered. Embedded in this variegation is a spatial axis of shared multimodal change that aligns with shared brain changes across psychiatric disorders and therefore represents a major high-priority target for future translational research in neuroscience.

Unraveling Down Syndrome: From Genetic Anomaly to Artificial Intelligence-Enhanced Diagnosis

Down syndrome arises from chromosomal non-disjunction during gametogenesis, resulting in an additional chromosome. This anomaly presents with intellectual impairment, growth limitations, and distinct facial features. Positive correlation exists between maternal age, particularly in advanced cases, and the global annual incidence is over 200,000 cases. Early interventions, including first and second-trimester screenings, have improved DS diagnosis and care. The manifestations of Down syndrome result from complex interactions between genetic factors linked to various health concerns. To explore recent advancements in Down syndrome research, we focus on the integration of artificial intelligence (AI) and machine learning (ML) technologies for improved diagnosis and management. Recent developments leverage AI and ML algorithms to detect subtle Down syndrome indicators across various data sources, including biological markers, facial traits, and medical images. These technologies offer potential enhancements in accuracy, particularly in cases complicated by cognitive impairments. Integration of AI and ML in Down syndrome diagnosis signifies a significant advancement in medical science. These tools hold promise for early detection, personalized treatment, and a deeper comprehension of the complex interplay between genetics and environmental factors. This review provides a comprehensive overview of neurodevelopmental and cognitive profiles, comorbidities, diagnosis, and management within the Down syndrome context. The utilization of AI and ML represents a transformative step toward enhancing early identification and tailored interventions for individuals with Down syndrome, ultimately improving their quality of life.

Moderate-to-vigorous intensity physical activity levels of children with intellectual disability during physical education classes

Background

Physical education (PE) class is an excellent way to improve moderate-to-vigorous intensity physical activity (MVPA). Increasing number of research has explored the children's PA based on movement during PE classes, but data for children with intellectual disability (ID) is still lacking.

Purpose

The purpose of this study was to investigate the current status of MVPA levels of children with ID during PE classes in China, as well as differences of MVPA levels according to gender and grade.

Methods

Accelerometers were used to record MVPA levels of fifty-three children with severe ID from 9 to 16 years of age (mean age: 12.60 ± 1.66 years) during standard PE classes.

Results

The mean time spent in MVPA during PE classes was 8.00 ± 2.10 min, meaning only 22.88% of PE class time was spent in MVPA. As grade levels progresses, time spent in MVPA during PE classes tended to decrease; the fourth-grade children tended to spend more time in MVPA during PE classes compared with the fifth-grade and the sixth-grade (9.15 vs. 7.61 vs. 7.25 min, all p < 0.05). Boys spend significantly more time in MVPA during PE classes than girls; both in the entire sample (9.20 vs. 5.70 min) as well as in each grade (9.76 vs. 6.09 min, 9.35 vs. 5.68 min, 8.31 vs. 5.59 min, all p < 0.05).

Conclusion

Findings from this study indicate that the proportion of PE class spent in the MVPA of children with ID was lower than the 50% recommended by the U.S. Department of Health and Human Services (DHHS) and U.K. Association for Physical Education (AfPE). And the amount of MVPA participation varied by the grade and gender as well as by the activity performed. Therefore, in order to help children with ID achieve MVPA goals, educators need to reevaluate the PE curriculum as well as take due consideration of grade and gender when devising new content.

Effectiveness of exergames programme to modify body composition and health-related physical fitness in adolescents with down syndrome after COVID-19 quarantine

AIMS

to determine the effect of a 20-week exergame program on different indicators of body composition and components of health-related physical fitness in adolescents with Down syndrome. Methods and Procedures Outcomes: 49 adolescents (19 female and 30 males; average age, 14.19 ± 2.06 years) with Down syndrome were recruited and randomized to two groups (control group vs. intervention group). Adolescents allocated in the control group carried out a physical activity program three times a week for 20 weeks meanwhile adolescents allocated in the exercise group performed an exergame program three times a week for 20 weeks.

RESULTS

The exercise group had significant improvements in all health-related physical fitness variables and there is an improvement in some body composition variables (p < 0.05).

CONCLUSIONS AND IMPLICATIONS

20 week exergame program consisting of 3 sessions of 60 minutes is able to improve levels of body composition and health-related physical fitness in adolescents with Down syndrome.Highlights Research in body composition and health-related physical fitness of people with Down syndrome has revealed that an exergame programme increases levels of health-related physical fitness in adolescents with Down syndromeAn exergame programme can improve differences in markers of body composition between the control group and the intervention groupThe intervention group that performed the exergame programme showed increases in health-related physical fitness levels after 20 weeks of intervention.The control group that performed a based on developing motor behaviour programme did not show differences in body composition or health-related physical fitness after 20 weeks of intervention.

Volumetric differences of thalamic nuclei in children with trisomy 21

OBJECTIVES

Histological studies have shown alterations of thalamic nuclei in patients with Down syndrome (DS). The correlation of these changes on MRI (magnetic resonance imaging) is unclear. Therefore, this study investigates volumetric differences of thalamic nuclei in children with DS compared to controls.

METHODS

Patients were retrospectively identified between 01/2000 and 10/2021. Patient inclusion criteria were: (1) 0-18 years of age, (2) diagnosis of DS, and (3) availability of a brain MRI without parenchymal injury and a non-motion-degraded volumetric T1-weighted sequence. Whole thalamus and thalamic nuclei (n = 25) volumes were analyzed bilaterally relative to the total brain volume (TBV). Two-sided t-tests were used to evaluate differences between groups. Differences were considered significant if the adjusted p-value was <0.05 after correction for multiple hypothesis testing using the Holm-Bonferroni method.

RESULTS

21 children with DS (11 females, 52.4%, mean age: 8.6 ± 4.3 years) and 63 age- and sex-matched controls (32 females, 50.8%, 8.6 ± 4.3 years) were studied using automated volumetric segmentation. Significantly smaller ratios were found for nine thalamic nuclei and the whole thalamus on the right and five thalamic nuclei on the left. TBV was significantly smaller in patients with DS (p < 0.001). No significant differences were found between the groups for age and sex.

CONCLUSIONS

In this exploratory volumetric analysis of the thalamus and thalamic nuclei, we observed statistically significant volumetric changes in children with DS. Our findings confirm prior neuroimaging and histological studies and extend the range of involved thalamic nuclei in pediatric DS.

Distinct neuroanatomical and neuropsychological features of Down syndrome compared to related neurodevelopmental disorders: a systematic review

Objectives

We critically review research findings on the unique changes in brain structure and cognitive function characteristic of Down syndrome (DS) and summarize the similarities and differences with other neurodevelopmental disorders such as Williams syndrome, 22q11.2 deletion syndrome, and fragile X syndrome.

Methods

We conducted a meta-analysis and systematic literature review of 84 studies identified by searching PubMed, Google Scholar, and Web of Science from 1977 to October 2022. This review focuses on the following issues: (1) specific neuroanatomic and histopathological features of DS as revealed by autopsy and modern neuroimaging modalities, (2) language and memory deficits in DS, (3) the relationships between these neuroanatomical and neuropsychological features, and (4) neuroanatomic and neuropsychological differences between DS and related neurodevelopmental syndromes.

Results

Numerous post-mortem and morphometric neuroimaging investigations of individuals with DS have reported complex changes in regional brain volumes, most notably in the hippocampal formation, temporal lobe, frontal lobe, parietal lobe, and cerebellum. Moreover, neuropsychological assessments have revealed deficits in language development, emotional regulation, and memory that reflect these structural changes and are more severe than expected from general cognitive dysfunction. Individuals with DS also show relative preservation of multiple cognitive, linguistic, and social domains compared to normally developed controls and individuals with other neurodevelopmental disorders. However, all these neurodevelopment disorders exhibit substantial heterogeneity among individuals.

Conclusion

People with Down syndrome demonstrate unique neurodevelopmental abnormalities but cannot be regarded as a homogenous group. A comprehensive evaluation of individual intellectual skills is essential for all individuals with neurodevelopment disorders to develop personalized care programs.

Evaluation of a smart home platform for adults with Down syndrome

People with Down syndrome (DS) encounter difficulties in their daily lives. In recent years, smart homes have provided some answers to the problem of residential autonomy. In fact, smart homes can provide support for complex routines and activities, while adjusting to the person's behaviors and needs and offering maximum control of the environment. In this context, the objectives of this study were to assess (i) the usability of the smart home platform as well as (ii) the impact of the use (for 6 months) of this platform by adults with DS on many dimensions such as residential autonomy, projection into the future, the development of a life plan, self-determination, quality of life, self-esteem, anxiety, and psychological well-being. The first objective of a preliminary study was to verify that the support platform we use is suitable and can be used effectively by people with DS. For the preliminary study, the evaluations show effective, satisfactory and efficient use of all applications. Regarding the objective of our study, the evaluations show positive impacts on many dimensions such as living skills, self-determination, quality of life, self-esteem, anxiety and certain components of life psychological well-being.

The use of the cambridge neuropsychological test automated battery for people born with Down syndrome and those born premature: A comparative systematic review

This review aimed to investigate the use of the Cambridge Neuropsychological Automated Testing Battery (CANTAB) for people at risk of cognitive impairment, especially those born with Down syndrome and those born preterm. Six databases were searched according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) standards, in addition to the bibliography index listed in the CANTAB site. Twenty four studies regarding Down syndrome and 17 regarding prematurity were reviewed and are here described. Both cognitive profiles were described, and their performance was compared on specific tasks and CANTAB tests. In this battery of tests, people with Down syndrome usually present impaired key cognitive domains, such as episodic memory and recognition memory. Results were presented considering general aspects described in the studies, specific findings such as dementia, the role of genetics, and cognitive profile, among other descriptions. Comparability between both populations in future studies is discussed.

Visuomotor skill learning in young adults with Down syndrome

BACKGROUND

Individuals with Down syndrome (DS) have impaired general motor skills compared to typically developed (TD) individuals.

AIMS

To gain knowledge on how young adults with DS learn and retain new motor skills.

METHODS AND PROCEDURES

A DS-group (mean age = 23.9 ± 3 years, N = 11), and an age-matched TD-group (mean age 22.8 ± 1.8, N = 14) were recruited. The participants practiced a visuomotor accuracy tracking task (VATT) in seven blocks (10.6 min). Online and offline effects of practice were assessed based on tests of motor performance at baseline immediate and 7-day retention.

OUTCOMES AND RESULTS

The TD-group performed better than the DS-group on all blocks (all P < 0.001). Both groups improved VATT-performance online from baseline to immediate retention, (all P < 0.001) with no difference in online effect between groups. A significant between-group difference was observed in the offline effect (∆TD - ∆DS, P = 0.04), as the DS-group's performance at 7-day retention was equal to their performance at immediate retention (∆DS, P > 0.05), whereas an offline decrease in performance was found in the TD-group (∆TD, P < 0.001).

CONCLUSIONS AND IMPLICATIONS

Visuomotor pinch force accuracy is lower for adults with DS compared to TD. However, adults with DS display significant online improvements in performance with motor practice similar to changes observed for TD. Additionally, adults with DS demonstrate offline consolidation following motor learning leading to significant retention effects.

Effect of hippotherapy on balance, functional mobility, and functional independence in children with Down syndrome: randomized controlled trial

Impaired muscle strength, proprioceptive and vestibular deficits, and orthopedic dysfunction are common disorders associated with Down syndrome (DS). Hippotherapy uses the horses' multidimensional movement to improve posture, balance, and overall function, both motor and sensory. Research evidence supports hippotherapy as an effective, medically recognized intervention for the rehabilitation of gross motor skills. The aim of this study was to determine the effect of hippotherapy on balance, functional mobility, and functional independence in children with DS. Thirty-four children with DS were randomly assigned to the experimental (hippotherapy) and control groups after the initial assessment. Both groups received physiotherapy including balance exercises, and the experimental group also received hippotherapy as an integrative therapy. Pediatric Balance Scale (PBS), Timed Up and Go Test (TUG), and Functional Independence Measure for Children (WeeFIM) were used before and after the intervention. Baseline outcome measures (PBS, TUG, WeeFIM) were statistically similar between groups (p > 0.05). After the intervention, PBS and TUG scores improved in both groups (p < 0.05). On the other hand, WeeFIM scores improved just in the hippotherapy group (p < 0.05).   Conclusion: Therefore, providing hippotherapy as an integrative therapy to physiotherapy will be more effective in improving the functional independence of children with DS.    Trial registration: NCT05297149 (March 2022, retrospectively registered). What is Known: • Hippotherapy has an improvement effect on balance and functional independence in different diseases and age groups, but the evidence is limited in DS. • There is limited evidence about the effect of hippotherapy on functional mobility in different diseases and age groups, but there is no evidence in DS. What is New: • Hippotherapy is a safe and effective approach to support improvement in functional independence in children with DS.

Early developmental profiles among infants with Down syndrome

BACKGROUND

Down syndrome (DS) generally predisposes children to a pattern of relative developmental strengths and challenges, but within-syndrome heterogeneity is also commonly observed across many dimensions. The present research examines whether heterogeneity in developmental presentation can be detected during infancy in DS and whether factors associated with differing profiles can be identified.

METHODS

Infants with DS (n = 75; age range: 3.9-17.6 months) were administered the Bayley Scales of Infant Development III (Bayley-III). A primary caregiver provided information regarding developmental history and family demographics. Latent profile analysis was conducted to identify whether early profiles were present across the five Bayley-III domains.

RESULTS

Three developmental profiles were observable within the sample: a 'Mild Delay' Profile, an 'Moderate Delay' Profile and a 'Pronounced Delay' Profile. In addition, chronological age, having received heart surgery and having received occupational therapy were associated with probability of profile membership.

CONCLUSIONS

Findings from this study contribute to the growing knowledgebase regarding heterogenous presentations associated with DS and can inform early intervention planning.

Acquisition of cognitive and communication milestones in infants with Down syndrome

BACKGROUND

Understanding the timing of developmental milestones in typical and clinical populations facilitates intervention planning and the early detection of risk for co-occurring conditions. Normative timing of developmental milestone achievement has been established for typically developing children. However, there is little information regarding the timing of cognitive and communication skill acquisition in young children with Down syndrome (DS). The objectives of this study are to (1) provide foundational information regarding the timing of cognitive and communication skill acquisition in infants with DS and (2) facilitate the early identification of infants with risk for co-occurring conditions.

METHOD

Seventy-four infants with DS (age range: 4-18 months) completed the Bayley Scales of Infant Development-III (Bayley 2006). Individual items from the cognitive and communication scales were selected for analysis. Parents provided information regarding their infant's developmental and family history.

RESULTS

The percentage of infants who attained each skill was calculated within 2-month age bands. For infants who did not show skill acquisition within each age band, the rates of prematurity, heart defects, corrective heart surgery and significant illness were calculated as well.

CONCLUSIONS

This study provides foundational information that can contribute to the formulation of a developmental schedule for cognitive and language milestone acquisition in infants with DS.

Effects of 24-week basketball programme on body composition and functional fitness on adults with Down syndrome

BACKGROUND

The body index [body mass, body mass index (BMI), waist circumference and waist-height ratio] and functional fitness (aerobic capacity, muscular strength, balance, flexibility and functional ability) of people with Down syndrome (DS) are substantially lower than those in the general population, as DS has an overall negative impact on health.

AIMS

This study explored the effect of a 24-week basketball training programme on the body composition and functional fitness of adults with DS.

METHODS AND PROCEDURE OUTCOMES

Twenty-two adults with DS (24 ± 6 years; 25 ± 4 kg/m² ) were randomly allocated to the experimental (n = 11, 67.04 kg) and control groups (n = 11, 69.36 kg). The experimental group performed 24 weeks of basketball programme training (3 times per week, 60 min per session), while the control group maintained their daily activities without any special physical training. Body composition and functional fitness parameters were measured before and after the intervention. To evaluate the differences between groups, an analysis of covariance (ANCOVA) was used while controlling for differences at baseline.

RESULTS

Hip circumference and waist-height ratio were statistically different at baseline between the intervention and control groups. After the 24-week basketball training programme, the results showed significant differences between the exercise and control groups for hip circumference, body mass, BMI, waist circumference, hip circumference, waist-height ratio, flexibility, aerobic capacity, static and dynamic balance, balance and basketball functional ability (P < 0.05). The exercise group showed significant improvements in all variables of body composition and functional fitness (P < 0.05) except for the waist-hip ratio. There was no statistical significance between all physical composition and functional health variables in the control group except for the standing long jump (P > 0.05), with effect sizes ranging from small to large.

CONCLUSIONS AND IMPLICATIONS

The basketball training programme improved body composition and functional fitness of adults with DS.

Evaluation of the Efficacy of Nasal Sedation Midazolam Compared with Dexmedetomidine in the Management of Uncooperative Children with Down Syndrome during Dental Treatment

Objective

This study aimed to compare the intranasal administration of midazolam and dexmedetomidine in uncooperative children with Down syndrome.

Materials and Methods

The sample consisted of 20 children with Down syndrome aged 5 to 11 years who were divided equally into two groups: Group 1 (experimental) nasal dexmedetomidine and Group 2 (control) nasal midazolam. The efficacy of both the drugs was evaluated according to Ohio State University Behavioral Rating Scale (OSUBRS), University of Michigan scale (UMSS), and Houpt general behavior scale.

Results

Both substances have been effective in the management of children with Down syndrome. There were no statistically significant differences for Ohio State University Behavioral Rating Scale (OSUBRS) (P value = 0.631), University of Michigan scale (UMSS) (P value = 0.739), and Houpt general behavior scale (P value = 0.481).

Conclusion

Both midazolam and dexmedetomidine nasal can be used to sedate children with Down syndrome.

Prospective memory in adults with down syndrome

Prospective memory (PM) refers to the ability to remember one's intentions (what I must do), at the appropriate time, in the future (when I must do it). The objective of this work is to study the performance of people with Down syndrome (DS) compared to two control groups, matched by mental age and chronological age. For this purpose, an adapted version of the virtual week, which is an ecological test to simulate the functioning of PM in everyday life, was used. The results suggest that people with DS have difficulties in PM that mainly concern the binding (association) between prospective (when to do) and retrospective (what to do) components. Moreover, people with DS perform better in PM when the task is repeated and time-based. These results are discussed in light of studies conducted with other populations.

The effect of the adapted soccer programme on motor learning and psychosocial behaviour in adolescents with Down syndrome

BACKGROUND

Numerous studies have proven the significant positive impact of the regular physical activity on general health conditions and quality of life of people with intellectual disability. In practice, various adapted sports activities are used. The current study deals with the effects of the soccer programme.

AIM

The purpose of the study is to evaluate the effects of adapted soccer on the motor learning and some psychosocial characteristics in adolescents with Down syndrome.

METHODS

Twenty-five participants were recruited and randomised into two groups (exercise and control). Adolescents placed in the exercise group carried out a special soccer programme twice a week during 16 weeks, while adolescents placed in the control group continued with their usual daily regime. Specific motor coordination, level of aggression, attention disorders, level of anxiety and depression, and social problems were measured before and after the training period. Mixed ANOVA were used to evaluate the effects of the experimental treatment.

RESULTS

The exercise group had significant improvements (P < 0.05) in one of three motor variables (only in the easiest task) and in all psychosocial variables. There are no one significant change in the control group. The adapted soccer programme influenced more seriously on psychosocial characteristics than on motor learning of adolescent with DS.

CONCLUSIONS

The results suggest that adapted soccer training can decrease aggression, anxiety and depression levels, and improve attention, social behaviour and simple motor skills in adolescents with Down syndrome.

RCAN1 knockout and overexpression recapitulate an ensemble of rest-activity and circadian disruptions characteristic of Down syndrome, Alzheimer's disease, and normative aging

BACKGROUND

Regulator of calcineurin 1 (RCAN1) is overexpressed in Down syndrome (DS), but RCAN1 levels are also increased in Alzheimer's disease (AD) and normal aging. AD is highly comorbid among individuals with DS and is characterized in part by progressive neurodegeneration that resembles accelerated aging. Importantly, abnormal RCAN1 levels have been demonstrated to promote memory deficits and pathophysiology that appear symptomatic of DS, AD, and aging. Anomalous diurnal rest-activity patterns and circadian rhythm disruptions are also common in DS, AD, and aging and have been implicated in facilitating age-related cognitive decline and AD progression. However, no prior studies have assessed whether RCAN1 dysregulation may also promote the age-associated alteration of rest-activity profiles and circadian rhythms, which could in turn contribute to neurodegeneration in DS, AD, and aging.

METHODS

The present study examined the impacts of RCAN1 deficiency and overexpression on the photic entrainment, circadian periodicity, intensity and distribution, diurnal patterning, and circadian rhythmicity of wheel running in young (3-6 months old) and aged (9-14 months old) mice of both sexes.

RESULTS

We found that daily RCAN1 levels in the hippocampus and suprachiasmatic nucleus (SCN) of light-entrained young mice are generally constant and that balanced RCAN1 expression is necessary for normal circadian locomotor activity rhythms. While the light-entrained diurnal period was unaltered, RCAN1-null and RCAN1-overexpressing mice displayed lengthened endogenous (free-running) circadian periods like mouse models of AD and aging. In light-entrained young mice, RCAN1 deficiency and overexpression also recapitulated the general hypoactivity, diurnal rest-wake pattern fragmentation, and attenuated amplitudes of circadian activity rhythms reported in DS, preclinical and clinical AD, healthily aging individuals, and rodent models thereof. Under constant darkness, RCAN1-null and RCAN1-overexpressing mice displayed altered locomotor behavior indicating circadian clock dysfunction. Using the Dp(16)1Yey/+ (Dp16) mouse model for DS, which expresses three copies of Rcan1, we found reduced wheel running activity and rhythmicity in both light-entrained and free-running young Dp16 mice like young RCAN1-overexpressing mice. Critically, these diurnal and circadian deficits were rescued in part or entirely by restoring Rcan1 to two copies in Dp16 mice. We also found that RCAN1 deficiency but not RCAN1 overexpression altered protein levels of the clock gene Bmal1 in the SCN.

CONCLUSIONS

Collectively, this study's findings suggest that both loss and aberrant gain of RCAN1 precipitate anomalous light-entrained diurnal and circadian activity patterns emblematic of DS, AD, and possibly aging.

Dohsa-hou training improves bimanual coordination among children with Down Syndrome

A child with Down syndrome (DS) is physically characterized by muscle hypotonia, joint instability, and poor motor coordination. Here, we tested whether Dohsa-hou training could improve motor coordination among children with DS, compared to a control condition. Forty children with DS were randomly assigned either to Dohsa-hou training or to a control condition. All participants completed a bimanual coordination test, at the following time points: baseline, seven weeks later at completion of the intervention, and again 4 weeks later at follow-up. Bimanual coordination accuracy and consistency improved from baseline to intervention completion and to follow-up, but only in the Dohsa-hou training, compared to the control group. The findings suggest that among children with DS and compared to a control condition, Dohsa-hou training has the potential to enhance the bimanual coordination, thus contributing to improved motor control of children with DS.

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.

Retrospective Case-Control Study of Communication and Motor Abilities in 143 Children With Suspected Childhood Apraxia of Speech: Effect of Concomitant Diagnosis

Purpose

This study sought to determine if children with childhood apraxia of speech (CAS) plus another major diagnosis (CAS+) are equivalent in communication and motor profiles to those with a primary diagnosis of CAS and no indication or report of any other diagnosis (CAS-Primary).

Method

This retrospective case-control study included a chart review of 143 children who were suspected of having CAS at Children's Hospital-Wisconsin between 1998 and 2004. Participants were between 30 and 127 months old and included 107 males. Participants were assigned to the suspected CAS-Primary group (n = 114) if they had characteristics of CAS but no other major diagnosis (e.g., galactosemia) and to the CAS+ group (n = 29) if a comorbid diagnosis was present. Groups were compared across demographic, communication, and motor characteristics.

Results

Children with CAS+ evidenced more severe motor profiles than those with CAS-Primary, χ2 = (1, n = 122) = 4.952, p = .026, and a small-to-medium effect size (Φ = .201). On average, communication profiles also tended to be more severe among those with CAS+ wherein receptive language was poorer and phonemic inventories were smaller than those with CAS-Primary.

Conclusions

These retrospective data suggest that comorbid diagnosis may play an important role in communication and motor development in children with suspected CAS. These exploratory findings should motivate future prospective studies that consider the role of concomitant diagnoses in symptom profile and response to treatment in children with CAS.

Psychomotor development in infants and young children with Down syndrome-A prospective, repeated measure, post-hoc analysis

Children with Down syndrome (DS) show delayed acquisition of cognitive and functional skills compared to typically developing children. The objective of this study was to accurately describe early development of infants and young children (children hereafter) with DS based on a large recent sample. We carried out repeated measure analysis of the global development quotient (GDQ) and developmental age using data from the Assessment of Systematic Treatment with Folinic Acid and Thyroid Hormone on Psychomotor Development of Down Syndrome Young Children (ACTHYF) study (NCT01576705). Because there was no statistically significant difference in the primary endpoint between active treatment and placebo, data from all treatment groups were pooled for post-hoc analysis. Data of 141 children with DS aged 6-18 months at inclusion were analyzed. Mean GDQ decreased over the study period, especially in the youngest age classes ([6-9] and [9-12] months), indicating that acquisition of skills occurred at a slower pace compared to typically developing children. Strongest deficits were observed for motor and hearing and language skills. Only GDQ at baseline correlated significantly with evolution of GDQ. Future studies should aim at elucidating the mechanisms underlying motor and language development. Early pharmacological interventions together with early childhood therapies might be necessary to improve the developmental trajectory of children with DS.

Care management in a French cohort with Down syndrome from the AnDDI-Rares/CNSA study

Down syndrome (DS) is a genetic neurodevelopmental disorder. In individuals with DS, a multidisciplinary approach to care is required to prevent multiple medical complications. The aim of this study was to describe the rehabilitation, medical care, and educational and social support provided to school-aged French DS patients with varying neuropsychological profiles. A mixed study was conducted. Quantitative data were obtained from a French multicentre study that included patients aged 4-20 years with diverse genetic syndromes. Qualitative data were collected by semi-structured face-to-face interviews and focus groups. Ninety-five DS subjects with a mean age of 10.9 years were included. Sixty-six per cent had a moderate intellectual disability (ID) and 18.9% had a severe ID. Medical supervision was generally multidisciplinary but access to medical specialists was often difficult. In terms of education, 94% of children under the age of six were in typical classes. After the age of 15, 75% were in medico-social institutions. Analysis of multidisciplinary rehabilitation conducted in the public and private sectors revealed failure to access physiotherapy, psychomotor therapy and occupational therapy, but not speech therapy. The main barrier encountered by patients was the difficulty accessing appropriate facilities due to a lack of space and long waiting lists. In conclusion, children and adolescents with DS generally received appropriate care. Though the management of children with DS has been improved considerably, access to health facilities remains inadequate.

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

Down Syndrome (DS) is the most common genetic alteration responsible for intellectual disability, which refers to deficits in both intellectual and adaptive functioning. According to this, individuals with Down Syndrome (DS) reach developmental milestones (e.g., sitting, walking, and babbling) in the same order as their typically developing peers, but later in life. Since developmental milestones are the first blocks on which development builds, the aims of the current study are to: (i) expand the knowledge of developmental milestone acquisition; and (ii) explore the relationship between developmental milestone acquisition and later development. For this purpose 105 children/adolescents with DS were involved in this study, divided in two groups, Preschoolers (n = 39) and School-age participants (n = 66). Information on the age of acquisition of Sitting, Walking, Babbling, and Sphincter Control was collected, together with cognitive, motor, and adaptive functioning. Sitting predicted later motor development, but, with age, it became less important in predicting motor development in everyday life. Babbling predicted later language development in older children. Finally, Sphincter Control emerged as the strongest predictor of motor, cognitive, language, and adaptive skills, with its role being more evident with increasing age. Our data suggest that the age of reaching the milestones considered in the study has an influence on successive development, a role that can be due to common neural substrates, the environment, and the developmental cascade effect.

Signalling pathways contributing to learning and memory deficits in the Ts65Dn mouse model of Down syndrome

Down syndrome (DS) is a genetic trisomic disorder that produces life-long changes in physiology and cognition. Many of the changes in learning and memory seen in DS are reminiscent of disorders involving the hippocampal/entorhinal circuit. Mouse models of DS typically involve trisomy of murine chromosome 16 is homologous for many of the genes triplicated in human trisomy 21, and provide us with good models of changes in, and potential pharmacotherapy for, human DS. Recent careful dissection of the Ts65Dn mouse model of DS has revealed differences in key signalling pathways from the basal forebrain to the hippocampus and associated rhinal cortices, as well as changes in the microstructure of the hippocampus itself. In vivo behavioural and electrophysiological studies have shown that Ts65Dn animals have difficulties in spatial memory that mirror hippocampal deficits, and have changes in hippocampal electrophysiological phenomenology that may explain these differences, and align with expectations generated from in vitro exploration of this model. Finally, given the existing data, we will examine the possibility for pharmacotherapy for DS, and outline the work that remains to be done to fully understand this system.

Complexity Analysis of the Default Mode Network Using Resting-State fMRI in Down Syndrome: Relationships Highlighted by a Neuropsychological Assessment

Background: Studies on complexity indicators in the field of functional connectivity derived from resting-state fMRI (rs-fMRI) in Down syndrome (DS) samples and their possible relationship with cognitive functioning variables are rare. We analyze how some complexity indicators estimated in the subareas that constitute the default mode network (DMN) might be predictors of the neuropsychological outcomes evaluating Intelligence Quotient (IQ) and cognitive performance in persons with DS. Methods: Twenty-two DS people were assessed with the Kaufman Brief Test of Intelligence (KBIT) and Frontal Assessment Battery (FAB) tests, and fMRI signals were recorded in a resting state over a six-minute period. In addition, 22 controls, matched by age and sex, were evaluated with the same rs-fMRI procedure. Results: There was a significant difference in complexity indicators between groups: the control group showed less complexity than the DS group. Moreover, the DS group showed more variance in the complexity indicator distributions than the control group. In the DS group, significant and negative relationships were found between some of the complexity indicators in some of the DMN networks and the cognitive performance scores. Conclusions: The DS group is characterized by more complex DMN networks and exhibits an inverse relationship between complexity and cognitive performance based on the negative parameter estimates.

Early appearance of developmental alterations in the dendritic tree of the hippocampal granule cells in the Ts65Dn model of Down syndrome

Down syndrome (DS), a genetic condition caused by triplication of chromosome 21, is characterized by alterations in various cognitive domains, including hippocampus-dependent memory functions, starting from early life stages. The major causes of intellectual disability in DS are prenatal neurogenesis alterations followed by impairment of dendritic development in early infancy. While there is evidence that the Ts65Dn mouse, the most widely used model of DS, exhibits dendritic alterations in adulthood, no studies are available regarding the onset of dendritic pathology. The goal of the current study was to establish whether this model exhibits early dendritic alterations in the hippocampus, a region whose function is severely damaged in DS. To this purpose, in Golgi-stained brains, we evaluated the dendritic arborization and dendritic spines of the granule cells of the hippocampal dentate gyrus in Ts65Dn mice aged 8 (P8) and 15 (P15) days. While P15 Ts65Dn mice exhibited a notably hypotrophic dendritic arbor and a reduced spine density, P8 mice exhibited a moderate reduction in the number of dendritic ramifications and no differences in spine density in comparison with their euploid counterparts. Both in P8 and P15 mice, spines were longer and had a longer neck, suggesting possible alterations in synaptic function. Moreover, P8 and P15 Ts65Dn mice had more thin spines and fewer stubby spines in comparison with euploid mice. Our study provides novel evidence on the onset of dendritic pathology, one of the causes of intellectual disability in DS, showing that it is already detectable in the dentate gyrus of Ts65Dn pups. This evidence strengthens the suitability of this model of DS as a tool to study dendritic pathology in DS and to test the efficacy of early therapeutic interventions aimed at ameliorating hippocampal development and, therefore, memory functions in children with DS.

Regional Alterations in Cortical Sulcal Depth in Living Fetuses with Down Syndrome

Down syndrome (DS) is the most common genetic cause of developmental disabilities. Advanced analysis of brain magnetic resonance imaging (MRI) has been used to find brain abnormalities and their relationship to neurocognitive impairments in children and adolescents with DS. Because genetic factors affect brain development in early fetal life, there is a growing interest in analyzing brains from living fetuses with DS. In this study, we investigated regional sulcal folding depth as well as global cortical gyrification from fetal brain MRIs. Nine fetuses with DS (29.1 ± 4.24 gestational weeks [mean ± standard deviation]) were compared with 17 typically developing [TD] fetuses (28.4 ± 3.44). Fetuses with DS showed lower whole-brain average sulcal depths and gyrification index than TD fetuses. Significant decreases in sulcal depth were found in bilateral Sylvian fissures and right central and parieto-occipital sulci. On the other hand, significantly increased sulcal depth was shown in the left superior temporal sulcus, which is related to atypical hemispheric asymmetry of cortical folding. Moreover, these group differences increased as gestation progressed. This study demonstrates that regional sulcal depth is a sensitive marker for detecting alterations of cortical development in DS during fetal life, which may be associated with later neurocognitive impairment.

Longitudinal neuroanatomical and behavioral analyses show phenotypic drift and variability in the Ts65Dn mouse model of Down syndrome

Mouse models of Down syndrome (DS) have been invaluable tools for advancing knowledge of the underlying mechanisms of intellectual disability in people with DS. The Ts(1716)65Dn (Ts65Dn) mouse is one of the most commonly used models as it recapitulates many of the phenotypes seen in individuals with DS, including neuroanatomical changes and impaired learning and memory. In this study, we use rigorous metrics to evaluate multiple cohorts of Ts65Dn ranging from 2014 to the present, including a stock of animals recovered from embryos frozen within ten generations after the colony was first created in 2010. Through quantification of prenatal and postnatal brain development and several behavioral tasks, our results provide a comprehensive comparison of Ts65Dn across time and show a significant amount of variability both across cohorts as well as within cohorts. The inconsistent phenotypes in Ts65Dn mice highlight specific cautions and caveats for use of this model. We outline important steps for ensuring responsible use of Ts65Dn in future research.This article has an associated First Person interview with the first author of the paper.

A multi-level developmental approach to exploring individual differences in Down syndrome: genes, brain, behaviour, and environment

In this article, we focus on the causes of individual differences in Down syndrome (DS), exemplifying the multi-level, multi-method, lifespan developmental approach advocated by Karmiloff-Smith (1998, 2009, 2012, 2016). We evaluate the possibility of linking variations in infant and child development with variations in the (elevated) risk for Alzheimer's disease (AD) in adults with DS. We review the theoretical basis for this argument, considering genetics, epigenetics, brain, behaviour and environment. In studies 1 and 2, we focus on variation in language development. We utilise data from the MacArthur-Bates Communicative Development Inventories (CDI; Fenson et al., 2007), and Mullen Scales of Early Learning (MSEL) receptive and productive language subscales (Mullen, 1995) from 84 infants and children with DS (mean age 2;3, range 0;7 to 5;3). As expected, there was developmental delay in both receptive and expressive vocabulary and wide individual differences. Study 1 examined the influence of an environmental measure (socio-economic status as measured by parental occupation) on the observed variability. SES did not predict a reliable amount of the variation. Study 2 examined the predictive power of a specific genetic measure (apolipoprotein APOE genotype) which modulates risk for AD in adulthood. There was no reliable effect of APOE genotype, though weak evidence that development was faster for the genotype conferring greater AD risk (ε4 carriers), consistent with recent observations in infant attention (D'Souza, Mason et al., 2020). Study 3 considered the concerted effect of the DS genotype on early brain development. We describe new magnetic resonance imaging methods for measuring prenatal and neonatal brain structure in DS (e.g., volumes of supratentorial brain, cortex, cerebellar volume; Patkee et al., 2019). We establish the methodological viability of linking differences in early brain structure to measures of infant cognitive development, measured by the MSEL, as a potential early marker of clinical relevance. Five case studies are presented as proof of concept, but these are as yet too few to discern a pattern.

The effect of swimming program on body composition levels in adolescents with Down syndrome

BACKGROUND

Down syndrome has been associated with more than 80 clinical characteristics such as diabetes, cardiovascular problems or obesity.

AIMS

The current study determined the effect of a 36 weeks swimming program on different indicators of body composition in adolescents with Down syndrome.

METHODS AND PROCEDURES OUTCOMES

45 adolescents with Down syndrome were recruited and randomized to two groups (control group vs. exercise group). Adolescents allocated in the control group carried out a recreational swimming program twice a week during 36 weeks meanwhile adolescents allocated in the exercise group did exercise three time a week during 36 weeks. BMI, Waist circumference, waist-to-height ratio, triceps, subscapular, suprailiac and thigh skinfold were measured.

RESULTS

ANCOVA tests were used to evaluate differences between groups in post-test intervention. Repeated measures of ANOVA were performed in order to assess differences in pre-test intervention in each group. t test were carried out to compare the pre-post-intervention differences in physical characteristics and body composition within each group. The exercise group had significant improvements in all variables of body composition (p < 0.05) except in subscapular and thigh skinfold.

CONCLUSIONS AND IMPLICATIONS

The results suggest that a 36 weeks swimming program consisting of 3 sessions of 50 minutes is able to decrease levels of body composition in a sample of adolescents with Down syndrome. The findings indicate that it would be important to generate high intensity sports programs in sports associations in order to obtain positive impact on body composition levels within this population.

Multiorgan involvement and management in children with Down syndrome

AIM

To review multiorgan involvement and management in children with Down syndrome (DS).

METHODS

A literature review of articles from 1980 to 2019 using the MEDLINE interface of PubMed was performed using the following search terms- [Down syndrome] or [Trisomy 21] AND [Cardiology] or [Respiratory] or [neurodevelopment] or [epilepsy] or [musculoskeletal] or [immune system] or [haematological] or [endocrine] or [gastrointestinal] or [ophthalmological] or [Ear Nose Throat] or [dermatology] or [renal].

RESULTS

Congenital heart disease particularly septal defects occur in over 60% of infants with DS and 5%-34% of infants develop persistent pulmonary hypertension of the newborn irrespective of a diagnosis of congenital heart disease. Early recognition and management of aspiration, obstructive sleep apnoea and recurrent lower respiratory tract infections (LRTI) could reduce risk of developing pulmonary hypertension in later childhood. Children with DS have an increased risk of autistic spectrum disorder, attention deficit disorder and epilepsy particularly infantile spasms, which are associated with poor neurodevelopmental outcomes. Congenital anomalies of the gastrointestinal and renal system as well as autoimmune diseases, coeliac disease, arthropathy, thyroid dysfunction fold diabetes mellitus and dermatological conditions are more common. Hearing and visual anomalies are also well recognised association with DS (Table 1).

CONCLUSION

Children with DS are at an increased risk of multiorgan comorbidities. Organ-specific health surveillance may provide holistic care for the children and families with DS throughout childhood.

Effect of AAC technology with dynamic text on the single-word recognition of adults with intellectual and developmental disabilities

Purpose: Single-word recognition can support participation in life, including engagement in leisure activities, navigation through the community, and vocational opportunities. Given the limited reading skills of many adults with intellectual and developmental disabilities (IDD) and limited speech, the current study evaluated the effects of using an augmentative and alternative communication (AAC) app, featuring dynamic text and speech output embedded in visual scene displays, on the single-word recognition performance of six adults with IDD who demonstrated limited speech.Method: A multiple baseline across participants single-subject design was used. Ten target sight words for each participant were selected on an individual basis, based on participant interest. Intervention consisted solely of interactions between investigators and individual participants using the app.Result: In the absence of any formal instruction and solely through the use of the AAC app interaction, three of the six participants demonstrated increased accuracy in single-word recognition.Conclusion: Results from the study were mixed, but suggest that AAC apps which provide the dynamic display of text in conjunction with voice output can assist some adults with IDD in achieving gains in single-word reading.

Cognitive Profiles and Autism Symptoms in Comorbid Down Syndrome and Autism Spectrum Disorder

OBJECTIVE

The prevalence of comorbid autism spectrum disorder (ASD) in children with Down syndrome (DS) is estimated to be around 16%. This study aims to fill gaps in the literature by describing developmental and behavioral phenotypes in this group relative to those with DS or ASD in isolation.

METHODS

Participants included 173 children (Mage = 73 months) with ASD, DS, or DS + ASD. Two 3 × 2 repeated-measures analyses of variance were completed with between-subject factors of the diagnostic group (DS, ASD, and DS + ASD) and within-subject factors of cognitive performance (verbal and nonverbal developmental quotient [DQ]) or ASD symptoms (social affect [SA] and restricted and repetitive behaviors [RRBs]).

RESULTS

Significant group-by-scale interactions were found, and pairwise comparisons revealed that for verbal DQ, DS + ASD < DS, ASD, whereas for nonverbal DQ, DS + ASD < DS < ASD. For SA, DS < DS + ASD < ASD, whereas for RRB, DS, DS + ASD < ASD.

CONCLUSION

Findings suggest greater cognitive impairment in DS + ASD on both verbal and nonverbal measures. Despite these significant cognitive challenges, ASD symptoms appeared less severe in DS + ASD relative to peers with ASD in isolation, although SA symptoms were elevated over DS-only. This unique DS + ASD presentation has important implications for early identification and intervention. Given previous research suggesting relative social strengths in DS and less severe ASD symptoms documented in this study, future research may benefit from investigating different aspects of SA (i.e., components related to reciprocal social interaction vs. social communication) in those with DS + ASD to more clearly delineate the social phenotype in this group and potentially inform intervention efforts.

Hypoplasia of cerebellar afferent networks in Down syndrome revealed by DTI-driven tensor based morphometry

Quantitative magnetic resonance imaging (MRI) investigations of brain anatomy in children and young adults with Down syndrome (DS) are limited, with no diffusion tensor imaging (DTI) studies covering that age range. We used DTI-driven tensor based morphometry (DTBM), a novel technique that extracts morphometric information from diffusion data, to investigate brain anatomy in 15 participants with DS and 15 age- and sex-matched typically developing (TD) controls, ages 6-24 years (mean age ~17 years). DTBM revealed marked hypoplasia of cerebellar afferent systems in DS, including fronto-pontine (middle cerebellar peduncle) and olivo-cerebellar (inferior cerebellar peduncle) connections. Prominent gray matter hypoplasia was observed in medial frontal regions, the inferior olives, and the cerebellum. Very few abnormalities were detected by classical diffusion MRI metrics, such as fractional anisotropy and mean diffusivity. Our results highlight the potential importance of cerebro-cerebellar networks in the clinical manifestations of DS and suggest a role for DTBM in the investigation of other brain disorders involving white matter hypoplasia or atrophy.

Perceptual similarity effect in people with Down syndrome

Background The perceptual similarity between two objects, specifically similarity in the shape of the referents, is a crucial element for relating words in earlier stages of development. The role of this perceptual similarity has not been systematically explored in children with Down syndrome (DS). Method: The aim was to explore the role of perceptual similarity in relationships between words in children with DS. Two groups, children with typical development (TD) and children with DS, matched by gender and mental age, participated in a priming task with a preferential looking paradigm. The task presented validated perceptually-related word pairs (prime-target) and perceptually unrelated pairs. In the priming task both groups were asked to look at a target image (e.g. ball) that was perceptually related (e.g. cookie) or unrelated (e.g. skirt) to the prime. Results: Participants from both groups looked more at targets without perceptual similarity than at those with similarity to the prime, suggesting an inhibition effect. Conclusions: This finding suggests the role of visual information, particularly the shape of the referents, in the construction of the lexical system.

Relations between Everyday Executive Functioning and Language in Youth with Down Syndrome and Youth with Autism Spectrum Disorder

Language and executive functioning are major impairments in many neurodevelopmental disorders, but little is known about the relations between these constructs, particularly using parent-report. Thus, the current research sought to examine relations between executive function and language in two groups - Down syndrome (DS; n=41; Mage = 11.2) and autism spectrum disorder (ASD; n=91; Mage = 7.7). Results were as follows: in DS, executive function predicted pragmatic, but not structural language after covarying for age, sex, and social functioning; in ASD, executive function predicted both. Findings highlight the interrelatedness of language and executive functioning and may have implications for intervention development.

Early intervention physical therapy using "Parent Empowerment Program" for children with Down syndrome in Pakistan: A feasibility study

PURPOSE

The aim of this study was to evaluate the feasibility and effectiveness of the Parent Empowerment Program (PEP) to help caretakers deliver a home program to promote developmental activities and gross motor function in their children with Down syndrome.

METHODS

Parents attended a 14-month program with training sessions 1-4 times a month. Outcomes were measured using a change in the Gross Motor Function Measure (GMFM-88) at baseline and assessment one.

RESULTS

Forty-eight families participated in the PEP. Children's mean age was 16.2 ± 10.8 months. There were significant changes in GMFM-88 scores between baseline and assessment one; t (30) =-9.158, p< 0.001; 95% CI -14.6 - -22.9. Previous hospitalization significantly affected GMFM scores.

CONCLUSION

This study describes a clinically applied research that focuses on program design, development and evaluation. Findings indicate that the PEP is effective in improving gross motor function in children with Down's syndrome in Pakistan. Parents were satisfied with the program outcomes and were able to cope with the requirements at home. The PEP had favorable outcomes and may be an effective method to support PT services in resource poor countries.

Spatiotemporal development of spinal neuronal and glial populations in the Ts65Dn mouse model of Down syndrome

BACKGROUND

Down syndrome (DS), caused by the triplication of chromosome 21, results in a constellation of clinical features including changes in intellectual and motor function. Although altered neural development and function have been well described in people with DS, few studies have investigated the etiology underlying the observed motor phenotypes. Here, we examine the development, patterning, and organization of the spinal cord throughout life in the Ts65Dn mouse, a model that recapitulates many of the motor changes observed in people with DS.

METHODS

Spinal cords from embryonic to adult animals were processed for gene and protein expression (immunofluorescence) to track the spatiotemporal development of excitatory and inhibitory neurons and oligodendroglia. Postnatal analyses were focused on the lumbar region due to the reflex and gait abnormalities found in Ts65Dn mice and locomotive alterations seen in people with DS.

RESULTS

Between embryonic days E10.5 and E14.5, we found a larger motor neuron progenitor domain in Ts65Dn animals containing more OLIG2-expressing progenitor cells. These disturbed progenitors are delayed in motor neuron production but eventually generate a large number of ISL1+ migrating motor neurons. We found that higher numbers of PAX6+ and NKX2.2+ interneurons (INs) are also produced during this time frame. In the adult lumbar spinal cord, we found an increased level of Hb9 and a decreased level of Irx3 gene expression in trisomic animals. This was accompanied by an increase in Calretinin+ INs, but no changes in other neuronal populations. In aged Ts65Dn animals, both Calbindin+ and ChAT+ neurons were decreased compared to euploid controls. Additionally, in the dorsal corticospinal white matter tract, there were significantly fewer CC1+ mature OLs in 30- and 60-day old trisomic animals and this normalized to euploid levels at 10-11 months. In contrast, the mature OL population was increased in the lateral funiculus, an ascending white matter tract carrying sensory information. In 30-day old animals, we also found a decrease in the number of nodes of Ranvier in both tracts. This decrease normalized both in 60-day old and aged animals.

CONCLUSIONS

We show marked changes in both spinal white matter and neuronal composition that change regionally over the life span. In the embryonic Ts65Dn spinal cord, we observe alterations in motor neuron production and migration. In the adult spinal cord, we observe changes in oligodendrocyte maturation and motor neuron loss, the latter of which has also been observed in human spinal cord tissue samples. This work uncovers multiple cellular perturbations during Ts65Dn development and aging, many of which may underlie the motor deficits found in DS.

The effect of training on variability and accuracy of overhand throwing in children with Down syndrome

OBJECTIVE

People with Down syndrome (DS) have higher variability in their motor skills compared to other counterparts without intellectual disability. Given that the effect of physical training on the variability and accuracy is unclear, the purpose of this study was to examine the effect of nine sessions of overhand throwing training on the variability and accuracy of overhand throwing in children with DS.

METHODS

Twenty-seven children with DS randomly assigned to experimental and control groups. In the pretest, two groups threw the tennis ball three times to the fixed target. Absolute error (AE) and the normalized root mean square (NoRMS) of segmental couplings of shoulder-elbow (NoRMS 1) and elbow-wrist (NoRMS 2) calculated from the scores of throwing and kinematics data, respectively. Then the experimental group participated in overhand throwing training for nine sessions. After that, the post-test was taken and ten days later, the retention test performed with pretest conditions.

RESULTS

The results of two-way ANOVA with repeated measures on AE values showed the experimental group in the post-test and retention phases was more accurate than the control group. Also, AE values of the experimental group in the post-test and retention phases were significantly lower than the pretest. The results of two-way ANOVA with repeated measures showed that NoRMS 1 in the experimental group was significantly lower than control group in the post-test and retention phases.

CONCLUSION

It seems the overhand throwing training can reduce the variability and increase the accuracy of overhand throwing in children with DS.

Motor and cognitive development of children with Down syndrome: The effect of acquisition of walking skills on their cognitive and language abilities

OBJECTIVE

This study investigated the relationship between motor and cognitive/language development in children with Down syndrome (DS). We also tested the hypothesis that acquisition of walking skills facilitates later cognitive/language development.

METHODS

Participants were 156 children with DS who were less than 48 months old and had undergone a health checkup by medical doctors and received rehabilitation treatment between April 2013 and March 2017 in Yokohama, Japan. To assess their development, the Kyoto Scale of Psychological Development (KSPD) 2001 was used, which measures development in three subdomains: Posture-Motor (P-M), Cognitive-Adaptive (C-A), and Language-Social (L-S). To investigate the relationship between motor and cognitive/language development, partial correlation analyses were conducted that controlled for participants' age. To test the effect of achieving walking skills, regression analyses were conducted using only data from participants who took the KSPD at least twice and could not walk at the initial test.

RESULTS

P-M developmental age (DA) was significantly and positively correlated with both C-A DA and L-S DA in children 1-3 years old. The relationship strengthened with increased age. Acquisition of walking skills had a significant positive effect on both the C-A DA and L-S DA at the second test when controlling for the C-A DA and L-S DA at the first test and age at the second test.

CONCLUSION

Motor development was correlated with both cognitive and language development in young children with DS. Results also suggested that achievement of walking could facilitate later cognitive/language development in children with DS.

Correlates of early cognition in infants with Down syndrome

BACKGROUND

While delays in cognitive development are detectable during early development in Down syndrome, the neuropsychological and biomedical underpinnings of cognitive skill acquisition in this population remain poorly understood.

METHOD

To explore this issue, 38 infants with Down syndrome [mean chronological age = 9.65 months; SD = 3.64] completed the Bayley Scales of Infant Development-III and a set of laboratory tasks that measured sustained attention (duration of visual attention during a 1-min object exploration task), attention shifting (mean latency to shift attention on an alternating object presentation task) and visual short-term memory (dishabituation to a novel object on a change preference task).

RESULTS

Latency to shift attention was negatively associated with Bayley Cognitive Scale raw scores, even when controlling for the effects of chronological age, r (33) = -.41, P = .02. In addition, prematurity status was associated with latency to shift attention.

CONCLUSIONS

Early attention shifting may be an important factor that facilitates overall cognitive skill acquisition in infants with Down syndrome, and premature birth may be a risk factor for difficulties on this dimension.

Estimates of the prevalence of speech and motor speech disorders in adolescents with Down syndrome

Although there is substantial rationale for a motor component in the speech of persons with Down syndrome (DS), there presently are no published estimates of the prevalence of subtypes of motor speech disorders in DS. The goal of this research is to provide initial estimates of the prevalence of types of speech disorders and motor speech disorders in adolescents with DS. Conversational speech samples from a convenience sample of 45 adolescents with DS, ages 10 to 20 years old, were analysed using perceptual and acoustic methods and measures in the Speech Disorders Classification System (SDCS). The SDCS cross-classified participants into five mutually exclusive speech classifications and five mutually exclusive motor speech classifications. For participants meeting criteria for Childhood Dysarthria or for Childhood Dysarthria concurrent with Childhood Apraxia of Speech, the SDCS provided information on participants' percentile status on five subtypes of dysarthria. A total of 97.8% of participants met SDCS criteria for Speech Disorders and 97.8% met criteria for Motor Speech Disorders, including Childhood Dysarthria (37.8%), Speech Motor Delay (26.7%), Childhood Dysarthria and Childhood Apraxia of Speech (22.2%), and Childhood Apraxia of Speech (11.1%). Ataxia was the most prevalent dysarthria subtype. Nearly all participants with DS in the present sample had some type of speech and motor speech disorder, with implications for theory, assessment, prediction, and treatment. Specific to treatment, the present findings are interpreted as support for motor speech disorders as a primary explanatory construct to guide the selection and sequencing of treatment targets for persons with DS. Abbreviations: CAS: Childhood Apraxia of Speech; CD: Childhood Dysarthria; DS: Down syndrome; NSA: Normal(ized) Speech Acquisition; PSD: Persistent Speech Delay; PSE: Persistent Speech Errors; SD: Speech Delay; SDCS: Speech Disorders Classification System; SE: Speech Errors; SMD: Speech Motor Delay.

Vocalization patterns in young children with Down syndrome: Utilizing the language environment analysis (LENA) to inform behavioral phenotypes

Children with Down syndrome (DS) are at higher risk for both delayed expressive language and poor speech intelligibility. The current study utilized the quantitative automated language environment analysis (LENA) to depict mother and child vocalizations and conversational patterns in the home of 43 children with DS, chronologically aged 24-64 months. Children with DS displayed fewer utterances than typically developing children; however, there was wide variability. Furthermore, children with DS did not show increased vocalization counts across their chronological ages. In contrast to previous findings, this study found that the mothers of children with DS had a reduced number of vocalizations. However, the vocalizations increased with age in comparison to mothers of typically developing children. Implications for targeted interventions that facilitate learning opportunities in bidirectional contexts for children with DS and their parents are discussed, with particular attention to quantify behavioral phenotypes utilizing a novel expressive language assessment tool.

Gross motor proficiency and intellectual functioning: A comparison among children with Down syndrome, children with borderline intellectual functioning, and typically developing children

This cross-sectional study examines differences in gross motor proficiency as a function of different intellectual functioning profiles. Two motor areas have been investigated as being equally essential to gross motor functions in every-day life: locomotion and object control.It aims to compare gross motor skills endorsed by children with Down syndrome (DS), children with borderline intellectual functioning (BIF), and typically developing children (TDC).Group 1 was composed of 18 children with DS (chronological age = 8.22), group 2 was composed of 18 children with BIF (chronological age = 9.32), and group 3 was composed of 18 children with typical development (TD) (chronological age = 9.28).Gross motor skills were measured through the test of gross motor development (TGMD-Test) composed of locomotion and object control tasks.Children with DS showed worse gross motor skills compared with children with BIF and typically developing children by underscoring both on all locomotion (e.g., walking, running, hopping, galloping, jumping, sliding, and leaping) and all object control tasks (e.g., throwing, catching, striking, bouncing, kicking, pulling, and pushing).In DS group strengths were found on run and slide skills, in BIF group strengths were on run, long jump and slide skills and in TDC group strengths were on run and slide skills. For all of the 3 groups the locomotor worst performed task was jump forward with arm swing.Findings suggest implications for further practice to develop evidence-based exercise programs aimed to rehabilitate gross motor skills through the regular participation in structured exercise activities.

Pediatric Brain Development in Down Syndrome: A Field in Its Infancy

OBJECTIVES

As surprisingly little is known about the developing brain studied in vivo in youth with Down syndrome (DS), the current review summarizes the small DS pediatric structural neuroimaging literature and begins to contextualize existing research within a developmental framework.

METHODS

A systematic review of the literature was completed, effect sizes from published studies were reviewed, and results are presented with respect to the DS cognitive behavioral phenotype and typical brain development.

RESULTS

The majority of DS structural neuroimaging studies describe gross differences in brain morphometry and do not use advanced neuroimaging methods to provide nuanced descriptions of the brain. There is evidence for smaller total brain volume (TBV), total gray matter (GM) and white matter, cortical lobar, hippocampal, and cerebellar volumes. When reductions in TBV are accounted for, specific reductions are noted in subregions of the frontal lobe, temporal lobe, cerebellum, and hippocampus. A review of cortical lobar effect sizes reveals mostly large effect sizes from early childhood through adolescence. However, deviance is smaller in adolescence. Despite these smaller effects, frontal GM continues to be largely deviant in adolescence. An examination of age-frontal GM relations using effect sizes from published studies and data from Lee et al. (2016) reveals that while there is a strong inverse relationship between age and frontal GM volume in controls across childhood and adolescence, this is not observed in DS.

CONCLUSIONS

Further developmentally focused research, ideally using longitudinal neuroimaging, is needed to elucidate the nature of the DS neuroanatomic phenotype during childhood and adolescence. (JINS, 2018, 24, 966-976).