Cognitive executive function in Down's syndrome

Executive function abilities in Mexican people with Down syndrome during the COVID-19 pandemic

BACKGROUND

The aim was to explore the executive function profile of a group of Mexican people with Down syndrome (DS) aged 12-30 years during the COVID-19 pandemic.

AIM

To analyse the relationships between mental, chronological age and eight domains of executive function.

METHOD

Participants were 42 people with DS with a chronological age (CA) of 12-30 years and a mean nonverbal mental age (MA) of 7 years. MA was evaluated with Raven's Progressive Matrices test and executive function with the Behaviour Rating Inventory of Executive Function (BRIEF-2); both were administered online.

RESULTS

The Monitor, Emotional Control, Initiative, and Organisation of Materials scales showed strengths, while Working Memory, Plan/Organise, Shift, and Inhibit scales showed weaknesses. CA correlated negatively with seven of the eight executive domains. Chronologically older participants showed less impairment in skills such as inhibition, emotional control, working memory, and monitoring. Nonverbal MA correlated negatively with two domains: emotional control and monitoring.

CONCLUSION

Participants' executive profile during the COVID-19 pandemic was consistent with that reported in studies prior to the pandemic.

Down syndrome frontal cortex layer III and layer V pyramidal neurons exhibit lamina specific degeneration in aged individuals

Selective vulnerability of neuronal populations occurs in both Down syndrome (DS) and Alzheimer's disease (AD), resulting in disproportional degeneration of pyramidal neurons (PNs) affecting memory and executive function. Elucidating the cellular mechanisms underlying the selective vulnerability of these populations will provide pivotal insights for disease progression in DS and AD. Single population RNA-sequencing analysis was performed on neurons critical for executive function, prefrontal cortex Brodmann area 9 (BA9) layer III (L3) and layer V (L5) excitatory PNs in postmortem human DS and age- and sex-matched control (CTR) brains. Data mining was performed on differentially expressed genes (DEGs) from PNs in each lamina with DEGs divergent between lamina identified and interrogated. Bioinformatic inquiry of L3 PNs revealed more unique/differentially expressed DEGs (uDEGs) than in L5 PNs in DS compared to CTR subjects, indicating gene dysregulation shows both spatial and cortical laminar projection neuron dependent dysregulation. DS triplicated human chromosome 21 (HSA21) comprised a subset of DEGs only dysregulated in L3 or L5 neurons, demonstrating partial cellular specificity in HSA21 expression. These HSA21 uDEGs had a disproportionally high number of noncoding RNAs, suggesting lamina specific dysfunctional gene regulation. L3 uDEGs revealed overall more dysregulation of cellular pathways and processes, many relevant to early AD pathogenesis, while L5 revealed processes suggestive of frank AD pathology. These findings indicate that trisomy differentially affects a subpopulation of uDEGs in L3 and L5 BA9 projection neurons in aged individuals with DS, which may inform circuit specific pathogenesis underlying DS and AD.

Exploring the Efficacy of a Dynamic Harness System on Gross Motor Development and Motivation for Infants With Down Syndrome: A Pilot Study

PURPOSE

To explore the benefits of a Partial Body Weight Support (PBWS) harness system within a play enriched environment on gross motor development and mastery motivation of infants with Down Syndrome (DS).

METHODS

A randomized crossover study with 17 pre-walking infants with DS in two conditions-play with or without the harness engaged-each for 3×/week over 3 weeks with a 1-week washout. Assessments took place at baseline, crossover, and completion.

RESULTS

Statistically and clinically significant changes were evident on the Gross Motor Function Measure-88; however, there were no significant changes in parent-reported mastery motivation.

CONCLUSION

The combination of PBWS harness system support and high frequency-facilitated play within an enriched play environment positively affected gross motor development. The intervention did not impact mastery motivation skills, and the direct impact of the harness remains unclear.

Everyday Executive Functioning Profiles in Adults with Down Syndrome

Research on everyday executive functions in individuals with Down Syndrome (DS) has focused mostly on children and adolescents. The current study examined everyday executive functions in DS adults. 27 DS adults (aged 22.00 to 42.00 years) were tested using the Behaviour Rating Inventory of Executive Function-Adult Informant Version (BRIEF-A). Findings revealed that DS adults exhibited greater impairments in Global Executive Composite (GEC), Working Memory, Plan/Organise, Task-Monitor and the Metacognition Index (MI) relative to typically developing adults in the normative sample. Substantial variabilities were found in all everyday executive function abilities among DS adults. Findings highlight the importance of making comprehensive assessments of everyday executive functions in DS individuals in order to identify problem areas and plan individualised support programmes.

Analysis of microisolated frontal cortex excitatory layer III and V pyramidal neurons reveals a neurodegenerative phenotype in individuals with Down syndrome

We elucidated the molecular fingerprint of vulnerable excitatory neurons within select cortical lamina of individuals with Down syndrome (DS) for mechanistic understanding and therapeutic potential that also informs Alzheimer's disease (AD) pathophysiology. Frontal cortex (BA9) layer III (L3) and layer V (L5) pyramidal neurons were microisolated from postmortem human DS and age- and sex-matched controls (CTR) to interrogate differentially expressed genes (DEGs) and key biological pathways relevant to neurodegenerative programs. We identified > 2300 DEGs exhibiting convergent dysregulation of gene expression in both L3 and L5 pyramidal neurons in individuals with DS versus CTR subjects. DEGs included over 100 triplicated human chromosome 21 genes in L3 and L5 neurons, demonstrating a trisomic neuronal karyotype in both laminae. In addition, thousands of other DEGs were identified, indicating gene dysregulation is not limited to trisomic genes in the aged DS brain, which we postulate is relevant to AD pathobiology. Convergent L3 and L5 DEGs highlighted pertinent biological pathways and identified key pathway-associated targets likely underlying corticocortical neurodegeneration and related cognitive decline in individuals with DS. Select key DEGs were interrogated as potential hub genes driving dysregulation, namely the triplicated DEGs amyloid precursor protein (APP) and superoxide dismutase 1 (SOD1), along with key signaling DEGs including mitogen activated protein kinase 1 and 3 (MAPK1, MAPK3) and calcium calmodulin dependent protein kinase II alpha (CAMK2A), among others. Hub DEGs determined from multiple pathway analyses identified potential therapeutic candidates for amelioration of cortical neuron dysfunction and cognitive decline in DS with translational relevance to AD.

Enhancing task performance in adults with intellectual disability through modified goal management training and assistive technology with errorless learning: A randomized controlled trial

Individuals with intellectual disabilities often fail to learn complex tasks. Modified Goal Management Training (mGMT) or Errorless Learning combined with assistive technology (App + EL) can help. The goal is to demonstrate the effectiveness of mGMT and/or App + EL in learning complex tasks. We employed a randomized controlled crossover design. One group started with mGMT (N = 16), and the other with App + EL (N = 15). We compared their performance with that of a passive control group (N = 15). The training consisted of six sessions of 30 minutes each. Success was analyzed using the Goal Attainment Scale (GAS). Three different tasks were assessed before and after each intervention period: "Practiced", "Non-Practiced", or "Previously Practiced". Generalization was evaluated through neuropsychological tests. Results indicated that both interventions significantly improved "Practiced" tasks compared with "Non-Practiced" tasks and the control group. Crossing the intervention did not interfere with the stable performance on the "Previously Practiced" task. However, starting with mGMT reduced, but did not eliminate, the efficacy of App + EL after crossing, but this pattern was not observed for the reverse sequence. Only the Tower of London task documented improvements related to interventions. In conclusion, the mGMT and App + EL were effective in learning complex tasks and retaining performance after learning a second task.Trial registration: German Clinical Trials Register identifier: DRKS00021674.

The Feasibility of an Online Language Program Delivered Through Music and the Impact of Dosage on Vocabulary Outcomes in Young Children With Down Syndrome

BACKGROUND

Few studies have explored the feasibility of online language interventions for young children with Down syndrome. Additionally, none have manipulated dose frequency or reported on the use of music as a medium through which language and sign can be learned.

PURPOSE

The purpose of this study was to (a) examine the feasibility and acceptability of an online language through music intervention for young children (1-3;6 years) with Down syndrome and (b) compare effectiveness at two intervention dose frequencies.

METHOD

The study was carried out in two phases using a mixed-methods design. Phase 1: Qualitative data were gathered from parents to examine feasibility when implementing a video-based language intervention. Phase 2: Seventy-six families participated in an online language intervention at home. Effectiveness was examined comparing two groups, randomly assigned to a high and low dose frequency. The Down Syndrome Education (DSE) checklists (combined) were the primary outcome measure. Process data were gathered to determine intervention acceptability in practice and to identify factors that would improve successful future implementation. Acceptability data were analyzed with reference to the theoretical framework of acceptability (Version 2).

RESULTS

Forty-three parents completed the Phase 1 scoping questionnaire, five of whom took part in focus groups. Once weekly morning sessions were indicated as the preferred scheduling choice. Phase 2 quantitative data were analyzed using beta regression adjusted for baseline scores and indicated no additional benefit to receiving the higher dose. However, exploratory interaction models suggested that the efficacy of the high-dose intervention was higher (than low-dose intervention) in participants with higher baseline DSE performance. Parents perceived the intervention to be effective and positive for the family.

CONCLUSION

The results add to our knowledge of real-world effective online interventions and suggest that a critical minimum language level is required for children with Down syndrome to benefit optimally from a higher intervention dose frequency.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.25979704.

Implications of Using the BRIEF-Preschool With School-Age Children With Down Syndrome

This study evaluated the appropriateness of scoring the Behavior Rating Inventory of Executive Function-Preschool (BRIEF-P) using age-equivalent scores generated from multiple measures of cognition and language among school-age children with Down syndrome (DS). Subscale T scores for 95 children with DS were contrasted using standard scoring on the Behavior Rating Inventory of Executive Function-Second edition (BRIEF-2; based on chronological age) to alternate scoring using the BRIEF-P (based on age-equivalent) for patterns of subscale intercorrelations, differences in mean scores, and agreement on findings from clinical cut-off scores. Results with children with DS suggested using (1) the BRIEF-P for children ages 2-5 years old, (2) the BRIEF-2 with chronological-age scoring or the BRIEF-P with age-equivalent scoring (with some caveats) for research on children ages 5-10 years old, and (3) the BRIEF-2 for children ages 11 and older.

BENDI: Improving Cognitive Assessments in Toddlers and Children with Down Syndrome Using Stealth Assessment

Cognitive assessment is a fundamental step in diagnosing intellectual and developmental disabilities, designing interventions, and evaluating their impact. However, developed and developing countries have different access to tools designed for these purposes. Our goal was to develop a battery for cognitive assessment mediated by digital technology that allows the exploration of cognitive domains (inhibitory control, attention, motor ability, and context memory) in children with Down Syndrome (DS) in Chile. Four tasks, based on established experimental paradigms modified to provide a game-like experience, were tested in 68 children with DS from 20 months to 12 years of age. We present evidence of reliability based on internal consistency and split-half analyses, with results ranging from adequate to excellent. Regarding validity, factorial and correlational analyses show evidence consistent with what was theoretically expected of internal structure, convergence, and divergence with other measures. Expected age trajectories were observed as well. Our data offer evidence that supports the use of tasks based on touch-screen devices for cognitive assessment in the population with DS. The tasks also have a low cultural load, so they could be validated and used in other contexts without the need for an adaptation process.

Motor Skills and Executive Functions in Pediatric Patients with Down Syndrome: A Challenge for Tailoring Physical Activity Interventions

Down syndrome (DS) is one of the most common chromosomal disorders. In addition to this variety of dysmorphic features. DS is also associated with a wide range of diseases and related comorbidities affecting different organs and systems. These comorbidities, together with societal and environmental influences, have a negative impact on physical activity in people with DS. Low levels of physical activity and energy expenditure have been identified as crucial players in worsening the acquisition of motor skills and executive functions. Executive functions are critical for the many skills (creativity, flexibility, self-control, and discipline) impacting our quality of life and make it possible to control impulses, mentally play with ideas, and stay focused. We proposed a broad overview of the available literature regarding motor skills and executive functions in pediatric patients with DS to understand the specific challenges for tailoring physical activity interventions. Motor skill interventions are effective in improving motor competence and performance on cognitive, emotional, and physical aspects in children with DS. Interventions based on executive functions in DS subjects are effective to contrast the cognitive decline and improve the everyday use of executive functions in youth and adults. Targeted interventions are mandatory for maximizing the benefits of physical activity, minimizing potential risks, and ultimately improving the overall health outcomes and quality of life for individuals with DS.

Correlating MRI-based brain volumetry and cognitive assessment in people with Down syndrome

INTRODUCTION

Down syndrome (DS) is the most common genetic cause of intellectual disability. Children and adults with DS show deficits in language performance and explicit memory. Here, we used magnetic resonance imaging (MRI) on children and adults with DS to characterize changes in the volume of specific brain structures involved in memory and language and their relationship to features of cognitive-behavioral phenotypes.

METHODS

Thirteen children and adults with the DS phenotype and 12 age- and gender-matched healthy controls (age range 4-25) underwent an assessment by MRI and a psychological evaluation for language and cognitive abilities.

RESULTS

The cognitive profile of people with DS showed deficits in different cognition and language domains correlating with reduced volumes of specific regional and subregional brain structures, confirming previous related studies. Interestingly, in our study, people with DS also showed more significant parahippocampal gyrus volumes, in agreement with the results found in earlier reports.

CONCLUSIONS

The memory functions and language skills affected in studied individuals with DS correlate significantly with the reduced volume of specific brain regions, allowing us to understand DS's cognitive-behavioral phenotype. Our results provide an essential basis for early intervention and the design of rehabilitation management protocols.

Psychometric evaluation of a working memory assessment measure in young children with Down syndrome

BACKGROUND

Working memory involves the temporary storage and manipulation of information and is frequently an area of challenge for individuals with Down syndrome (DS). Despite the potential benefits of intervention, laboratory assessments of working memory that could capture intervention effects have not undergone rigorous evaluation for use with young children with DS. It is critical to evaluate assessments of working memory in young children with DS to ensure the reliable and accurate measurement of performance.

AIM

This study evaluated an adapted laboratory measure of working memory for young children with DS 2-8 years old.

METHOD

A self-ordered pointing task, the Garage Game, was administered to 78 children with DS (mean = 5.17 years; SD = 1.49). Adaptations were made to the task to minimize potential DS phenotype-related language and motor confounds.

RESULTS

Results indicate that the measure is feasible, scalable, and developmentally sensitive, with minimal floor and practice effects for this population within this chronological and developmental age range.

CONCLUSION

These findings demonstrate that the Garage Game is promising for use in studies of early working memory and treatment trials that aim to support the development of this critical dimension of executive functioning for children with DS.

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.

Executive functioning in adolescents and adults with Silver-Russell syndrome

Silver-Russell syndrome (SRS) is a rare imprinting disorder characterized by prenatal and postnatal growth retardation. The two principal causes of SRS are loss of methylation on chromosome 11p15 (11p15 LOM) and maternal uniparental disomy of chromosome 7 (UPD(7)mat). Knowledge of the neuropsychological profile of SRS remains sparse and incomplete even if several difficulties related to attention and learning have been reported both in the literature and by patients with SRS. These difficulties could be the result of troubles in different cognitive domains, but also of executive dysfunction. Nevertheless, executive functioning has never been investigated, even though executive functions play an essential role in psychological development, and are extensively involved in daily life. The present study explored the executive functioning of individuals with SRS due to UPD(7)mat or 11p15 LOM. A battery of executive tasks assessing cognitive flexibility, inhibitory control, and working memory, together with a task assessing sustained attention, was administered to 19 individuals with SRS (13-39 years) and 19 healthy controls. The Behavior Rating Inventory of Executive Function was also completed by the participants' families. The results showed that participants with SRS had similar performance (z-scores) to our controls, in a context of normal intellectual efficiency. Group comparisons with Bayesian statistics showed a single difference between the 11p15 LOM and control groups: the completion time for part A of the Trail Making Test appeared to be longer in the 11p15 LOM group than in the control group. However, at the clinical level, several participants with SRS had clinically significant scores on various measures of EFs. Thus, the cognitive phenotype of SRS did not appear to be characterized by executive dysfunction, but individuals with SRS could be at high risk of developing executive dysfunction or attention-deficit/hyperactivity disorder. These results provide new insights into the neuropsychological profile of individuals with SRS.

Embedding key word sign prompts in a shared book reading activity: The impact on communication between children with Down syndrome and their parents

BACKGROUND

Children with Down syndrome have speech and language difficulties that are disproportionate to their overall intellectual ability and relative strengths in the use of gesture. Shared book reading between parents and their children provides an effective context in which language development can be facilitated. However, children with Down syndrome often take a passive role in shared book reading and the use of key word signing (KWS) as a shared book reading technique has never been investigated.

AIMS

This study aimed to compare children with Down syndrome's participation and use of KWS across two methods of shared book reading - one in which a book had key-word sign prompts embedded (signed condition) and the other in which a book was read as normal (unsigned condition). Measures of child and parent communicative behaviour were taken in each condition to establish if differences emerged.

METHODS & PROCEDURES

A total of 36 children with Down syndrome (aged between 18 and 61 months) and their mothers took part in the study. Parent-child dyads were videoed at home reading two books, one in a signed and one in an unsigned condition. Child measures included total number of signs produced in each condition and levels of attention and initiation as measured by the Pivotal Behaviour Rating Scale. Parent measures included total number of utterances, mean length of utterance (MLU) in morphemes and vocabulary diversity (VOCD). Parental measures were transcribed using the Codes for Human Analysis Transcripts (CHAT) software and analysed by the Computerised Language Analysis software (CLAN). Contrasts in outcomes between the signed and unsigned conditions were estimated using Poisson and linear mixed-effects models, determined by the type of data.

OUTCOMES & RESULTS

Results showed that children attempted to sign significantly more in the signed than unsigned condition, as well as showing significant increases in their levels of attention and initiation. There was also a significant increase in the total number of utterances used by parents in the signed versus unsigned condition and a decrease in MLU. VOCD was similar in both conditions.

CONCLUSIONS & IMPLICATIONS

This study shows that the simple act of embedding key word signs into commercially available books, during shared book reading between parents and young children with Down syndrome, positively affects children's participation (initiation and attention) and use of KWS. The use of KWS as a core shared book reading technique may therefore be a fruitful avenue to facilitate growth in the language abilities of young children with Down syndrome.

WHAT THIS PAPER ADDS

What is already known on this subject Most children with Down syndrome have significant speech and language difficulties, with relative strengths in the use of gesture. Shared book reading is an activity reported to positively affect language. However, children with Down syndrome are reported to take a passive role in shared book reading and are therefore more dependent on their parents to use techniques that facilitate their levels of participation, in order to maximise potential benefits. To the best of our knowledge, the communicative effects of embedding key word signing (KWS) in shared book reading have never been examined with children with Down syndrome. What this paper adds to existing knowledge This is the first study to investigate the communicative impact of parents embedding KWS in a shared book reading activity with their young children with Down syndrome. Our findings show that this relatively simple manipulation resulted in Increase in children's sign attempts. Increase in children's overall participation in shared book reading (indicated by levels of attention and initiation). Increase in the number of utterances produced by parents (primarily as a result of repetitions). Decrease in parental mean length of utterance. These findings suggest that embedding KWS in shared book reading is likely to facilitate increased language abilities in this cohort. What are the potential or actual clinical implications of this work? Shared book reading is part of the daily routine for many parents and their children with Down syndrome. Integrating KWS is a relatively simple adaptation to this activity which is likely to enhance children's language skills. Therapists can encourage parents to do this at home to support work carried out at school and in a clinical setting.

Combined sensory integration therapy plus neurodevelopmental therapy (NT) versus NT alone for motor and attention in children with Down syndrome: a randomized controlled trial

In this study, we aimed to analyze the incremental effects of sensory integration therapy (SIT) plus neurodevelopmental therapy (NT) versus NT alone on the attention and motor skills in children with Down syndrome (DS). We randomly assigned into experimental (i.e. SIT + NT; n = 21) and control (i.e. NT alone; n = 21) groups. While NT was applied to both groups for six weeks, SIT was applied simultaneously to the experimental group for six weeks. Participants' motor functions (Bruininks-Oseretsky Test of Motor Proficiency-Short form (BOT-2 SF)) and attention skills (Stroop TBAG (Turkish Scientific and Technological Research Association) Form) were evaluated before and after treatment (6 weeks later). Stroop TBAG and BOT-2 SF scores of the groups were similar at the baseline (p > 0.05). Significant improvement from baseline was observed in both BOT-2 SF, and Stroop TBAG results in both groups (p < 0.05). In addition, the improvement in both BOT-2 SF and Stroop TBAG results was found to be greater in the experimental group compared to the control group (p < 0.01). There were clear advantages to adding SIT to NT alone when seeking to improve motor and attention skills in children with DS.

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.

Social abilities in young Mexicans with Down syndrome during the COVID-19 pandemic

Background: Social abilities include interpersonal skills, interaction, and social responsibility. The nature of these abilities has not been explored in young people with Down syndrome (DS) during the social isolation of the COVID-19 pandemic. Method: The aim of this online study was to describe the social profile of a group of 30 Mexican people with DS, with a chronological age of 15-29 years, and explore the variables related to their psychosocial profiles. A sociodemographic questionnaire, mental age examination, and socialization battery were applied. Social behavior was analyzed in domains that facilitate socialization (leadership, joviality, social sensitivity, respect/self-control), in domains that disrupt socialization (aggressiveness/stubbornness, apathy/withdrawal, anxiety/shyness), and on a global scale. Results: Participants' scores in the facilitative domains were above average, and their scores in the disruptive domains were below average, as expected. Scores on the respect/self-control scale were associated with chronological age (CA), and those on the global scale with mental age (MA). Discussion: No impairments were found in the social skills of young people with DS according to the parameters of the scale. The development of the social profile with CA and MA stimulates cognition and promotes independence, autonomy, and proactivity. Parents' role in regulating children's behavior was an important factor in managing their social isolation during the COVID-19 pandemic.

Differential expression of the neuronal CB1 cannabinoid receptor in the hippocampus of male Ts65Dn Down syndrome mouse model

Down syndrome (DS) or Trisomy 21 is the most common genetic cause of mental retardation with severe learning and memory deficits. DS is due to the complete or partial triplication of human chromosome 21 (HSA21) triggering gene overexpression and protein synthesis alterations responsible for a plethora of mental and physical phenotypes. Among the diverse brain target systems that affect hippocampal-dependent learning and memory deficit impairments in DS, the upregulation of the endocannabinoid system (ECS), and notably the overexpression of the cannabinoid type-1 receptor (CB1), seems to play a major role. Combining various protein and gene expression targeted approaches using western blot, qRT-PCR and FISH techniques, we investigated the expression pattern of ECS components in the hippocampus (HPC) of male Ts65Dn mice. Among all the molecules that constitute the ECS, we found that the expression of the CB1 is altered in the HPC of Ts65Dn mice. CB1 distribution is differentially segregated between the dorsal and ventral part of the HPC and within the different cell populations that compose the HPC. CB1 expression is upregulated in GABAergic neurons of Ts65Dn mice whereas it is downregulated in glutamatergic neurons. These results highlight a complex regulation of the CB1 encoding gene (Cnr1) in Ts65Dn mice that could open new therapeutic solutions for this syndrome.

Language and executive functioning in young adults with Down syndrome

BACKGROUND

This study examined the association between executive functioning and language in young adults with Down syndrome (DS).

METHOD

Nineteen young adults with DS (aged 19-24 years) completed standardised measures of overall cognition, vocabulary, verbal fluency and executive function skills.

RESULTS

Friedman's analysis of variance (χ² (3) = 28.15, P < .001) and post hoc comparisons indicated that, on average, participants had a significantly lower overall non-verbal than verbal cognitive age equivalent and lower expressive than receptive vocabulary skills. Using Spearman correlations, performance on a verbal measure of cognition inhibition was significantly negatively related to receptive vocabulary (ρ = -.529, adjusted P = .036) and verbal fluency (ρ = -.608, adjusted P = .022). Attention was significantly positively correlated with receptive (ρ = .698, adjusted-p = .005) and expressive (ρ = .542, adjusted P = .027) vocabulary. Verbal working memory was significantly positively associated with receptive vocabulary (ρ = .585, adjusted P = .022) and verbal fluency (ρ = .737, adjusted P = .003). Finally, visuospatial working memory was significantly associated with receptive vocabulary (ρ = .562, adjusted P = .027).

CONCLUSIONS

Verbal and non-verbal measures of executive functioning skills had important associations with language ability in young adults with DS. Future translational research is needed to investigate causal pathways underlying these relationships. Research should explore if interventions aimed at increasing executive functioning skills (e.g. attention, inhibition and working memory) have the potential to lead to increases in language for young adults with DS.

Evaluating working memory outcome measures for children with Down syndrome

BACKGROUND

There is a critical need for the psychometric evaluation of outcome measures to be used in clinical trials targeting cognition in Down syndrome (DS). This study examines a specific cognitive skill that is of particular importance in DS, working memory, and the psychometric properties of a set of standardised measurements to assess working memory in individuals with DS.

METHODS

Ninety children and adolescents ages 6 to 18 years old with DS were assessed on a selection of verbal and visuospatial working memory subtests of standardised clinical assessments at two time points to examine feasibility, distributional qualities, test-retest reliability and convergent validity against a priori criteria. Caregivers also completed an adaptive behaviour questionnaire to address working memory subtests' associations with broader developmental functioning.

RESULTS

The Stanford Binet-5 Verbal Working Memory, Differential Ability Scales-2 Recognition of Pictures, Stanford Binet-5 Nonverbal Working Memory and Wechsler Intelligence Scale for Children-5 Picture Span measures met the most psychometric criteria overall across the full age and IQ range of the study. Although Differential Ability Scales-2 Recall of Sequential Order and Differential Ability Scales-2 Recall of Digits Backward met the fewest a priori criteria, follow-up analyses suggested greater feasibility in specific age and IQ ranges.

CONCLUSIONS

Several working memory measures appear to be psychometrically sound and appropriate for use in clinical trials for children with DS, especially when focusing on raw scores. However, floor effects on standard scores and feasibility of some measures were problematic. Guidelines for use of the working memory subtests with this population are provided.

Infant precursors of executive function in Down syndrome

BACKGROUND

Although early features of infant cognition are predictive of executive function (EF) in typically developing (TD) children, there is little information regarding the developmental origins of EF in neurogenetic conditions, such as Down syndrome (DS).

METHODS

The current study compared the performance of infants with and without DS on three dimensions that are hypothesised EF precursors: visual engagement, attention shifting and action planning. Additionally, the relationship between these EF precursors at Time 1 and EF performance at Time 2 (6 months later) was examined in the DS group. Participants were 36 infants with DS, M chronological age = 12.65 months, SD = 2.11; M developmental age = 8.84 months, SD = 2.22, and 36 TD infants, M chronological age = 8.62, SD = 3.06; M developmental age = 8.64 months, SD = 3.40.

RESULTS

Infants with DS visually engaged with objects for longer durations and demonstrated challenges with action planning compared with TD infants at Time 1. Attention shifting at Time 1 significantly predicted EF performance at Time 2 in the DS group.

CONCLUSIONS

This study provides evidence that an early atypical presentation of EF precursors is detectable during infancy in DS and is predictive of subsequent EF performance. These findings contribute to the identification of areas of early cognitive risk in DS and can inform future interventions in this population.

Semantic Verbal Fluency in Youth with Down Syndrome: Analysis of Conventional and Contextual Cluster Formation

Expressive language delays and executive functioning challenges are common in youth with Down syndrome (DS). Verbal fluency is one method to investigate these constructs. We examined semantic verbal fluency responses to determine patterns in response generation and the psychometric properties of coded cluster formations. Participants were 97 children and adolescents with DS ranging in age from 6 to 19 years old. The semantic verbal fluency task was administered at two time points, two weeks apart. Heterogeneity in performance was observed for responses when coded either with conventional or contextual classifications. Overall, the number of switches in conventional classifications was greater than contextual classifications. This implies that participants did not use traditional (conventional) categories to organize their semantic verbal fluency responses, but may have been using contextual strategies. However, the number of switches and cluster size variables had poor to moderate test-retest reliability, which indicated that participants did not stay consistent with their performance over the two-week testing interval, regardless of the strategies used. Therefore, conventional and contextual clusters and switches as a measure of executive control may not be appropriate for all individuals with DS and additional attention is warranted to determine the utility of response coding in this population.

The role of distinct executive functions on adaptive behavior in children and adolescents with Down syndrome

Difficulties in executive function are a relatively well-characterized feature of the neuropsychological profile in Down syndrome (DS), yet the impact of these challenges on aspects of daily functioning remain poorly understood. We examined the role of specific executive functions on domains of adaptive behavior in children and adolescents with DS. Participants included 68 children and adolescents with DS between 6-17 years old (mean chronological age = 12.56 years; SD = 3.22) and their caregivers. Parent reported executive function skills were measured using the BRIEF-2 and adaptive behavior was measured using the Vineland Adaptive Behavior Scales-III. Results identified working memory as a significant predictor of Communication, Daily Living, and Socialization skills, and Shifting significantly predicted Daily Living and Socialization. Findings demonstrate the relation between executive functions and adaptive behavior and highlight the effects of working memory on aspects of daily functioning for individuals with DS.

Trisomy of Human Chromosome 21 Orthologs Mapping to Mouse Chromosome 10 Cause Age and Sex-Specific Learning Differences: Relevance to Down Syndrome

Down syndrome (DS), trisomy of human chromosome 21 (Hsa21), is the most common genetic cause of intellectual disability. The Dp10(1)Yey (Dp10) is a mouse model of DS that is trisomic for orthologs of 25% of the Hsa21 protein-coding genes, the entirety of the Hsa21 syntenic region on mouse chromosome 10. Trisomic genes include several involved in brain development and function, two that modify and regulate the activities of sex hormones, and two that produce sex-specific phenotypes as null mutants. These last four are the only Hsa21 genes with known sexually dimorphic properties. Relatively little is known about the potential contributions to the DS phenotype of segmental trisomy of Mmu10 orthologs. Here, we have tested separate cohorts of female and male Dp10 mice, at 3 and 9 months of age, in an open field elevated zero maze, rotarod, and balance beam, plus the learning and memory tasks, spontaneous alternation, puzzle box, double-H maze, context fear conditioning, and acoustic startle/prepulse inhibition, that depend upon the function of the prefrontal cortex, striatum, hippocampus, and cerebellum. We show that there are age and sex-specific differences in strengths and weaknesses, suggesting that genes within the telomere proximal region of Hsa21 influence the DS phenotype.

The Clinical and Neuropathological Features of Sporadic (Late-Onset) and Genetic Forms of Alzheimer's Disease

The purpose of this review is to compare and highlight the clinical and pathological aspects of genetic versus acquired Alzheimer's disease: Down syndrome-associated Alzheimer's disease in (DSAD) and Autosomal Dominant Alzheimer's disease (ADAD) are compared with the late-onset form of the disease (LOAD). DSAD and ADAD present in a younger population and are more likely to manifest with non-amnestic (such as dysexecutive function features) in the prodromal phase or neurological features (such as seizures and paralysis) especially in ADAD. The very large variety of mutations associated with ADAD explains the wider range of phenotypes. In the LOAD, age-associated comorbidities explain many of the phenotypic differences.

Towards Designing Mobile Apps for Independent Travel

Performing daily independent activities can be a challenge for people with Down's Syndrome (DS). This article investigates how to better support these activities with smart devices based on three cycles of a collaborative participatory action research (PAR) process. The first cycle involved semi-structured interviews ( n = 4 ) with parents and an online survey ( n = 39 ) with people with DS and their parents to explore barriers and opportunities for independent activities. This cycle highlighted that travelling independently was a common challenge among discussed barriers to independent activities for young adults with DS, an issue that smart devices have the potential to overcome. The second cycle involved seven focus group discussions ( n = 20 ) with parents ( n = 13 ) and young adults with DS ( n = 7 ) for gaining deeper insights into barriers to independent travel. We explored key barriers to independent travel and gathered design requirements for smartphone apps to overcome these barriers. In the third cycle, we designed a digital prototype based on participant recommendations and conducted seven focus group meetings ( n = 19 ) with caregivers ( n = 12 ) and individuals with DS ( n = 7 ). This final cycle reviewed the proposed digital prototype and validated the key barriers found in the second cycle. Overall, our studies confirmed that mobile technology can support people with DS in performing daily life activities that increase social inclusion. The studies resulted in identified barriers and requirements along with co-designed solutions for independent travel apps.

Behavioral Inflexibility Across Two Neurogenetic Conditions: Down Syndrome and Fragile X Syndrome

Behavioral inflexibility (BI) has been highlighted to occur across genetic and neurodevelopmental disorders. This study characterized BI in two common neurogenetic conditions: Fragile X syndrome (FXS) and Down syndrome (DS). Caregivers of children with FXS (N = 56; with ASD = 28; FXS only = 28) and DS (N = 146) completed the Behavioral Inflexibility Scale (BIS) via an online survey. Total BIS scores were higher in FXS+ASD than both FXS only and DS (p <.001). Most endorsed items were similar across the three groups, but scores were higher in the FXS+ASD group. In all groups, BI associated with other clinical variables (receptive behaviors, anxiety, social communication). The current data suggest that BI is variable across neurogenetic conditions and higher in individuals with comorbid ASD.

Relationship between Apgar scores and long-term cognitive outcomes in individuals with Down syndrome

This study examined the contribution of the Apgar score at 1 and 5 min after birth to later cognitive functioning in 168 individuals with Down syndrome who were between 6 and 25 years of age at time of cognitive testing. Our results showed that a lower Apgar score at 1 min was related to a worse performance in later cognitive measures of receptive vocabulary, verbal comprehension and production, visual memory and working memory. Results also showed that a lower Apgar score at 5 min was only related to worse later outcomes of verbal comprehension and production and auditory working memory. Our findings suggest a need for future studies investigating how specific perinatal events reflected in the Apgar score are linked to later cognitive functioning in individuals with Down syndrome.

Executive Function Improves Following Acute Exercise in Adults with Down Syndrome

The influence of exercise on brain function is an important topic, especially in persons with intellectual deficits. The aim of this study is to determine the effect of an acute bout of resistance training (RT) compared to assisted cycle therapy (ACT) and no training (NT) in adults with DS on cognitive function. Fourteen participants attended four sessions: a baseline assessment, an assisted cycling therapy (ACT) session, a resistance training (RT) session, and a session of no training (NT). In the RT session, the leg press, chest press, seated row, leg curl, shoulder press, and latissimus pulldown were performed. The ACT session consisted of 30 min of cycling and in NT session consisted of 20 min of board games. Inhibition was measured by the Erikson flanker task and cognitive planning was measured by the Tower of London test and both were administered prior to (pretest) and after each intervention (posttest). Our results showed that inhibition time improved more following RT and ACT than NT. There was also a significant difference between ACT and NT. For cognitive planning, improvements were seen following ACT and NT. In conclusion, an acute session of ACT demonstrated a significant trend towards improvements in executive functions in adults with DS which we interpreted using a model of neural changes and the cognitive stimulation hypothesis.

C21orf91 Regulates Oligodendroglial Precursor Cell Fate-A Switch in the Glial Lineage?

Neuropathological diseases of the central nervous system (CNS) are frequently associated with impaired differentiation of the oligodendroglial cell lineage and subsequent alterations in white matter structure and dynamics. Down syndrome (DS), or trisomy 21, is the most common genetic cause for cognitive impairments and intellectual disability (ID) and is associated with a reduction in the number of neurons and oligodendrocytes, as well as with hypomyelination and astrogliosis. Recent studies mainly focused on neuronal development in DS and underestimated the role of glial cells as pathogenic players. This also relates to C21ORF91, a protein considered a key modulator of aberrant CNS development in DS. We investigated the role of C21orf91 ortholog in terms of oligodendrogenesis and myelination using database information as well as through cultured primary oligodendroglial precursor cells (OPCs). Upon modulation of C21orf91 gene expression, we found this factor to be important for accurate oligodendroglial differentiation, influencing their capacity to mature and to myelinate axons. Interestingly, C21orf91 overexpression initiates a cell population coexpressing astroglial- and oligodendroglial markers indicating that elevated C21orf91 expression levels induce a gliogenic shift towards the astrocytic lineage reflecting non-equilibrated glial cell populations in DS brains.

Meta-analysis on inhibition from childhood to young adulthood in people with Down syndrome

BACKGROUND

Few studies have investigated inhibition in people with Down syndrome (DS), indicating contradictory results.

AIM

This meta-analysis investigated if people with DS show more severe difficulties on inhibition, compared to typically developing (TD) children matched on a measure of mental age (MA).

METHODS AND PROCEDURES

Literature search included studies conducted before March 2019, combining the following keywords: "Down syndrome" with "Inhibition", "Interference control", "Effortful control", "Impulsivity", "Self-regulation", and "Executive functions". Descriptive information was coded, according to inclusions criteria. Meta-analysis of standardized differences between DS and TD groups' means was performed. Relevant moderators were also considered.

OUTCOMES AND RESULTS

Eight studies were included in the meta-analysis, including 161 people with DS and 160 TD children. The results indicated that people with DS showed significantly lower inhibition abilities when they are matched on MA with TD children, instead no significant differences emerged when this matching was not provided. A high heterogeneity across studies was estimated.

CONCLUSIONS AND IMPLICATIONS

This meta-analysis indicates that people with DS show, on average, an inhibition deficit compared to TD matched children, albeit not a severe one. These results suggest the importance of investigating in depth inhibition processes in people with DS from childhood to young adulthood.

Executive Functions and Attention Processes in Adolescents and Young Adults with Intellectual Disability

(1) Background: We made a comprehensive evaluation of executive functions (EFs) and attention processes in a group of adolescents and young adults with mild intellectual disability (ID). (2) Methods: 27 adolescents and young adults (14 females and 13 males) with ID, aged between 15.1 and 23 years (M = 17.4; SD = 2.04), were compared to a control group free of cognitive problems and individually matched for gender and age. (3) Results: As for EFs, individuals with ID were severely impaired on all subtests of the Behavioral Assessment of Dysexecutive Syndrome (BADS) battery. However, we also found appreciable individual differences, with eight individuals (approximately 30%) scoring within normal limits. On the attention tests, individuals with ID were not generally slower but presented specific deficits only on some attention tests (i.e., Choice Reaction Times, Color Naming and Color–Word Interference, and Shifting of Attention for Verbal and for Visual Targets).The role of a global factor (i.e., cognitive speed) was modest in contributing to the group differences; i.e., when present, group differences were selectively associated with specific task manipulations, not global differences in cognitive speed. (4) Conclusions: The study confirmed large group differences in EFs; deficits in attentional processing were more specific and occurred primarily in tasks taxing the selective dimension of attention, with performance on intensive tasks almost entirely spared.

Executive function in Down syndrome: A meta-analysis

BACKGROUND

Executive function (EF) refers to a set of cognitive processes involved in goal-oriented behavior-especially inhibition, attention shifting, and working memory. EF has been identified as a probable area of difficulty in Down syndrome (DS), but the exact nature of the difficulty has not been well-established.

AIMS

The meta-analysis sought to confirm or disconfirm EF as an area of difficulty in DS and elucidate an EF profile.

METHODS AND PROCEDURES

A random-effects meta-analysis was conducted on 57 studies that compared a group with DS to a typically developing (TD) mental age matched group on one or more executive function tasks. Heterogeneity was examined and moderators analyzed.

OUTCOMES AND RESULTS

The overall mean weighted effect size was large (d = -0.87), indicating poorer EF in groups with DS vs TD groups. Heterogeneity was significant, and moderator analysis revealed an EF profile with a very large effect for verbal WM/STM, a large effect for shifting, and moderate effects for inhibition and nonverbal WM/STM. Skewness analysis suggested that mean effect sizes might have been dampened, especially for WM/STM and shifting.

CONCLUSIONS AND IMPLICATIONS

Individuals with DS display a pronounced difficulty in EFs; implications for interventions and future research are discussed.

Neuropsychological profile of adults with Down syndrome and moderate intellectual disability

BACKGROUND

The neuropsychological profile of individuals with Down syndrome (DS) has been described as being characterized by dissociations between verbal and visual abilities, as well as between verbal comprehension and production abilities (higher visual than verbal abilities and higher verbal comprehension than verbal production abilities). However, the studies that reached these conclusions based these conclusions mainly on inter-group differences in children but not on intra-group differences.

AIMS

The study explores dissociations in adults with DS, taking inter-group and intra-group differences into account.

METHOD AND PROCEDURES

The sample was composed of 40 adults with DS and 38 adults with moderate intellectual disability (ID) but without DS, matched for chronological age, sex, and intellectual level.

OUTCOMES AND RESULTS

The participants with DS, unlike the other group, exhibited similar performance in their verbal and visual abilities, as well as in their verbal comprehension and production abilities (intra-group differences). In addition, they showed worse performance in verbal general measures and verbal comprehension abilities but similar performance in visual general measures and verbal production abilities (inter-group differences) compared with those without DS with similar intellectual levels on standardized measures.

CONCLUSIONS AND IMPLICATIONS

The observed intra-group differences highlight that a lack of dissociation between verbal and visual abilities, as well as between verbal comprehension and production abilities, seems to be a specific feature of adults with DS.

Goal-directed action planning in infants with Down syndrome

BACKGROUND

Down syndrome (DS) is a neurogenetic disorder associated with risk for executive dysfunction, or difficulties with the cognitive processes required for planning volitional, goal-directed behaviour. This study examines the developmental origins of difficulties with goal-directed action planning in infants with DS to inform our understanding of the cognitive phenotype associated with DS and its implications for intervention.

METHOD

First, the study compared the performance of infants with DS (n = 44, mean chronological age = 7.5 months, SD = 2.3) and typically developing infants (n = 31, mean chronological age = 7.5 months, SD = 2.9) on plan production and planning efficiency during an early planning task. Next, potential sources of variability in planning behaviour (motor performance and sensory processing) within the DS sample were examined. All infants completed an early planning laboratory task and the Bayley Scales of Infant Development-III Cognitive Scale. The motor and sensory skills of infants with DS were assessed by the motor scales of the Bayley Scales of Infant Development-III and the Infant Sensory Profile-2. DS-related biomedical history information was provided by caregivers for the infants with DS.

RESULTS

Between-group differences in planning were observed on the dimensions of strategy production and completion, such that infants with DS were less efficient in their strategy execution than typically developing infants. In the DS group, motor skills and sensory processing were associated with planning efficiency on all components of the early planning task.

CONCLUSIONS

Less efficient action planning in infants with DS may disrupt the shaping of goal-directed behaviour, and the identification of early risk factors associated with planning efficiency has important implications for early intervention.

A Representational Approach to Executive Function Impairments in Young Adults with Down Syndrome

Based on a representational perspective, this paper examines executive functioning in Down syndrome. Sixteen young adults with Down syndrome, 16 mental age- and 16 age-matched controls were compared on script sequencing and sorting tasks. Participants were asked to reestablish the sequential structure of script actions given with or without irrelevant actions. Impairments in script information processing were observed only in young adults with Down syndrome, who performed more slowly than controls, making mistakes in ordering actions, but rejecting aberrant elements. These data are consistent with the view that Down syndrome impairs the syntactic but not semantic dimension of script representation.

The Acquisition of Survey Knowledge by Individuals With Down Syndrome

People with Down syndrome often exhibit deficiencies in wayfinding activities, particularly route learning (e.g., Courbois et al., 2013; Davis et al., 2014; Farran et al., 2015). Evidence concerning more sophisticated survey learning has been sparse. In the research reported here, two experiments are reported that evaluated survey learning of youth with DS and typically developing children (TD) matched on mental age. In Experiment 1, participants learned two overlapping routes consisting of three turns each through a virtual environment depicting 9 square city blocks. Following acquisition, they were tested on multiple measures of survey knowledge: finding a shortcut, identifying the direction of landmarks not currently visible from their location in the environment, and recognizing a bird's-eye representation of the overall environment. Under these conditions, which should provide relatively optimal opportunities for survey learning, the participants with DS performed comparably to TD participants matched on non-verbal ability on all of our measures of survey learning. Hence, we concluded that people with DS can acquire some survey knowledge when tasked with learning a small environment and given the opportunity to do so. In Experiment 2, the experimenter navigated participants through a large, relatively complex, virtual environment along a circuitous path, beginning and ending at a target landmark. Then, the participants were placed at a pre-specified location in the environment that they had viewed previously and instructed to navigate to the same target (a door) using the shortest possible path from their current location. They completed the task three times: once after being shown the environment one time, once after three exposures, and once after five exposures. Results indicated that the participants with DS exhibited significantly less skill at identifying the shortcut than did the TD participants, with differences emerging as the number of exposures increased. Participants with DS were also less able to recall landmarks at the end of the experiment. Overall, however, the performance of both groups was relatively poor in both experiments - with the performance of participants with DS being worse as conditions became less optimal. These results were discussed in terms of underlying mechanisms that may account for variations in survey learning as environmental complexity increases.

Emotion knowledge in neurotypical children and in those with down syndrome

This research aimed to assess two components of emotion knowledge (EK): receptive EK with face emotion identification and matching tasks, and emotion situation knowledge with the emotion attribution task (EAT). Study 1 assessed the development of EK in 265 neurotypical (NT) children (4-11 years), divided into four age groups. Overall, results showed a significant improvement of EK with age in the NT population for the three tasks, especially between the ages of 4/5 and 6/7. Children were less successful at the EAT in comparison to the other two tasks, indicating that receptive EK develops earlier than emotion situation knowledge. The presence of visual context (EAT) does not help to improve our children's overall facial emotion recognition, especially for anger and sadness, while these emotions are well recognized in isolated facial expressions (emotion identification). Study 2 compared EK between 32 children with Down syndrome (CA: M = 13 years, SD = 2.13) and 32 NT children (CA: M = 5.3 years, SD = 1.36): matched on a vocabulary task. Children with DS had more difficulties in EK than NT children. They had lower performances on the identification and the EAT tasks, while exhibited similar performances to their NT controls on the emotion matching task. Moreover, good abilities to identify emotion expressions seem to be a prerequisite for successful face-context recognition in NT children, but not in children with DS. Difficulties encountered by children with DS could result from executive dysfunction when dealing with complex visual information in addition to emotion processing difficulties.

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.

Cognitive abilities and life experience in everyday planning in adolescents with intellectual disabilities: Support for the difference model

BACKGROUND

The literature on planning ability in individuals with intellectual disability (ID) provides no clarity on whether their ability matches their mental age (MA) or not. Perhaps can planning experience explain the mixed results. The current study investigated to what extent cognitive abilities and life experience can explain everyday planning ability in individuals with ID and to what extent results from everyday planning tasks support the developmental or the difference model of ID.

METHOD

Planning tests, cognitive ability tasks and a self-rated life experience form were administered to 71 adolescents with ID and 62 children with a typical development matched on MA.

RESULTS

Adolescents with ID exhibited planning ability according to their MA. Regression analyses showed that the predictors of planning differed between the groups. The cognitive measures could predict planning in both groups, but life experience only contributed positively to planning in the MA group, whereas chronological age was negatively correlated with successful planning in the ID group.

CONCLUSIONS AND DISCUSSION

The results support the difference model of ID. When matched on MA, the individuals with ID will solve the planning task in a qualitatively different manner. Additionally, the participants with ID could not utilise their life experience when solving the planning task, contrary to the MA group. Practitioners should be aware that individuals with ID might need more everyday planning training throughout adolescence. To support adolescents with ID, practitioners may focus on supporting the individual's cognitive abilities rather than relying on their prior knowledge.

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.

Different abilities needed at home and school: The relation between executive function and adaptive behaviour in adolescents with Down syndrome

Studies have shown that executive function abilities are related and have predictive power over adaptive behaviour in both typical and atypical populations. This study examined the relationship between executive functioning and adaptive behaviour in adolescents with Down syndrome, as it has not been studied before in this population. We propose and test a model of how each core EF (i.e., working memory, inhibition, and flexibility) contributes to each domain of AB (i.e., conceptual, social, and practical). We found that parent reported Conceptual skills were related to working memory, while teacher reported Conceptual and Practical skills were related to inhibition and flexibility. We hypothesise that these findings are related to the different requirements and expectations of the home and school environments: the more predictable home environment requires the adolescent to rely on working memory for his everyday activities, while the changing and challenging school environment requires the inhibition common behaviours and to flexibly change actions to be successful.

Altered Hippocampal-Prefrontal Neural Dynamics in Mouse Models of Down Syndrome

Altered neural dynamics in the medial prefrontal cortex (mPFC) and hippocampus may contribute to cognitive impairments in the complex chromosomal disorder Down syndrome (DS). Here, we demonstrate non-overlapping behavioral differences associated with distinct abnormalities in hippocampal and mPFC electrophysiology during a canonical spatial working memory task in three partially trisomic mouse models of DS (Dp1Tyb, Dp10Yey, and Dp17Yey) that together cover all regions of homology with human chromosome 21 (Hsa21). Dp1Tyb mice show slower decision-making (unrelated to the gene dose of DYRK1A, which has been implicated in DS cognitive dysfunction) and altered theta dynamics (reduced frequency, increased hippocampal-mPFC coherence, and increased modulation of hippocampal high gamma); Dp10Yey mice show impaired alternation performance and reduced theta modulation of hippocampal low gamma; and Dp17Yey mice are not significantly different from the wild type. These results link specific hippocampal and mPFC circuit dysfunctions to cognitive deficits in DS models and, importantly, map them to discrete regions of Hsa21.

Aberrant Oligodendrogenesis in Down Syndrome: Shift in Gliogenesis?

Down syndrome (DS), or trisomy 21, is the most prevalent chromosomal anomaly accounting for cognitive impairment and intellectual disability (ID). Neuropathological changes of DS brains are characterized by a reduction in the number of neurons and oligodendrocytes, accompanied by hypomyelination and astrogliosis. Recent studies mainly focused on neuronal development in DS, but underestimated the role of glial cells as pathogenic players. Aberrant or impaired differentiation within the oligodendroglial lineage and altered white matter functionality are thought to contribute to central nervous system (CNS) malformations. Given that white matter, comprised of oligodendrocytes and their myelin sheaths, is vital for higher brain function, gathering knowledge about pathways and modulators challenging oligodendrogenesis and cell lineages within DS is essential. This review article discusses to what degree DS-related effects on oligodendroglial cells have been described and presents collected evidence regarding induced cell-fate switches, thereby resulting in an enhanced generation of astrocytes. Moreover, alterations in white matter formation observed in mouse and human post-mortem brains are described. Finally, the rationale for a better understanding of pathways and modulators responsible for the glial cell imbalance as a possible source for future therapeutic interventions is given based on current experience on pro-oligodendroglial treatment approaches developed for demyelinating diseases, such as multiple sclerosis.

Operation of cognitive memory inhibition in adults with Down syndrome: Effects of maintenance load and material

BACKGROUND

Cognitive inhibition is one of the executive functions; this process over memory plays a fundamental role in recalling relevant information. The aims of this study were to understand the effects of maintenance load and stimuli on the operation of cognitive inhibition over memory in working memory tasks in adults with Down syndrome.

METHOD

The study included 36 individuals with Down syndrome (mean age = 33.44 years, standard deviation = 7.54 years, 50% women) and 36 individuals with neurotypical development (mean age = 33.55 years, standard deviation = 7.52 years, 50% women). The participants performed a working memory task in which they had to solve an interference problem during the maintenance phase.

RESULTS

The Down syndrome group performed worse on cognitive inhibition over memory than the neurotypical development group. Both groups had lower recall with interference and under high-load conditions. In the neurotypical development group, memory was similar with both materials. The Down syndrome group performed better with non-social stimuli than with social stimuli.

CONCLUSIONS

Understanding the variables that influence cognitive inhibition over memory will help in planning effective interventions for people with Down syndrome. Considering the results, special importance should be placed on work with social stimuli, at least in individuals with Down syndrome.

Psycholinguistic profile of young adults with Down syndrome

BACKGROUND

The phenotype of Down syndrome (DS) is usually characterized by relative strengths in visual skills and severe deficits in auditory processing; this has consequences for language and communication. To date, it is not known whether this pattern characterizes the psycholinguistic profile of young adults with DS.

AIMS

This study aimed to assess whether, relative to their cognitive level, young adults with DS present a specific and homogeneous phenotype for both auditory and visual psycholinguistic skills.

METHODS AND PROCEDURES

Fifty young adults with DS and 50 peers with other intellectual disability (ID) were equated in chronological age and nonverbal cognition and were compared regarding their performance in auditory and visual psycholinguistic functions.

OUTCOMES AND RESULTS

Participants with DS showed more phenotypic-specific deficits in auditory psycholinguistic skills than in those involved in visual processing. However, phenotypic-specific impairments in visual psycholinguistic skills were also observed, while no significant between-group differences were found for some auditory psycholinguistic skills.

CONCLUSIONS AND IMPLICATIONS

The psycholinguistic pattern of young adults with DS is not homogeneous with respect to auditory and visual processing. The profile of specific deficits suggests that the educative support for young adults with DS may need to be specific.