Executive function in adolescents with Down Syndrome

Brief Report: Contrasting Profiles of Everyday Executive Functioning in Smith-Magenis Syndrome and Down Syndrome

Everyday executive function (EF) was examined in Smith-Magenis syndrome (SMS), associated with high risk of behaviour disorder, and Down syndrome (DS), associated with relatively low risk of behaviour disorder. Caregivers of 13 children with SMS and 17 with DS rated everyday EF using the Behavioral Rating Inventory of Executive Functioning-Preschool. Greater everyday EF deficits relative to adaptive ability were evident in SMS than in DS. The SMS profile of everyday EF abilities was relatively uniform; in DS emotional control strengths and working memory weaknesses were evident. Findings implicate broad everyday EF difficulties in SMS compared to DS, corresponding with increased rates of behaviour disorder in SMS. Findings further suggest that everyday EF profiles may, in part, be syndrome related.

Memory profiles in Down syndrome across development: a review of memory abilities through the lifespan

Down syndrome (DS) is associated with a variety of cognitive impairments, notably memory impairments. Due to the high prevalence rates of early-onset dementia associated with DS, it is imperative to understand the comprehensive development of memory impairments beginning in childhood and into adulthood, as this may help researchers identify precursors of dementia at earlier stages of development and pinpoint targets for memory intervention. The current paper provides a systematic, developmentally focused review of the nature of memory difficulties in DS across the lifespan. Specifically, this review summarizes what is known about long-term, short-term, and working memory abilities (distinguishing between verbal and nonverbal modalities) in DS, compared to both mental age-matched typically developing peers and individuals with other forms of intellectual disability (ID) at three developmental stages (i.e., preschool, adolescence, and adulthood). Additionally, this review examines the degree of impairment reported relative to typically developing mental age-matched peers in the existing literature by examining effect size data across memory domains as a function of age. With few exceptions, memory abilities were impaired across the lifespan compared to mental age-matched typically developing peers. Relative to other groups with ID, research findings are mixed. Our review of the literature identified a scarcity of memory studies in early childhood, particularly for STM and WM. In adulthood, research was limited in the LTM and WM domains and very little research has compared memory abilities in older adults with DS to those with typical development. Looking to the future, longitudinal studies could provide a better understanding of the developmental trajectory of memory abilities in DS, and the possible associations between memory abilities and real-world functioning. This research could ultimately inform interventions to improve independence and overall quality of life for those with DS and their families.

Learning by observation and learning by doing in Down and Williams syndromes

New skills may be learned by active experience (experiential learning or learning by doing) or by observation of others' experience (learning by observation). In general, learning by observation reduces the time and the attempts needed to learn complex actions and behaviors. The present research aimed to compare learning by observation and learning by doing in two clinical populations with different etiology of intellectual disability (ID), as individuals with Down syndrome (DS) and individuals with Williams syndrome (WS), with the hypothesis that specific profiles of learning may be found in each syndrome. To this end, we used a mixture of new and existing data to compare the performances of 24 individuals with DS, 24 individuals with WS and 24 typically developing children on computerized tasks of learning by observation or learning by doing. The main result was that the two groups with ID exhibited distinct patterns of learning by observation. Thus, individuals with DS were impaired in reproducing the previously observed visuo-motor sequence, while they were as efficient as TD children in the experiential learning task. On the other hand, individuals with WS benefited from the observational training while they were severely impaired in detecting the visuo-motor sequence in the experiential learning task (when presented first). The present findings reinforce the syndrome-specific hypothesis and the view of ID as a variety of conditions in which some cognitive functions are more disrupted than others because of the differences in genetic profile and brain morphology and functionality. These findings have important implications for clinicians, who should take into account the genetic etiology of ID in developing learning programs for treatment and education.

Pupil response and attention skills in Down syndrome

Down syndrome (DS) is characterized by attentional problems. Little is known about the neural correlates of attention problems in DS due to difficulties in evaluation. Pupil dilation, associated with an increase in cognitive load and locus coeruleus-noradrenaline system activity in humans, is a neurophysiological measurement that may help to characterize such problems. The aim of this research was to investigate the link between a phasic pupil dilation response and target detection in people with DS, as compared with a control group with typical development (TD) matched by mental age. Participants performed an "oddball" task by means of an eye-tracker and a series of neuropsychological tests. Although the DS and control group demonstrated similar attentional skills and behavioral performance, the participants with DS showed greater pupil dilation. This result suggests that people with DS expend extra cognitive effort to achieve performance similar to those with TD. This finding is discussed in light of the attentional process in DS and the reliability of pupil dilation measurement in the study of attention and other cognitive processes in DS.

A cross-sectional analysis of executive function in Down syndrome from 2 to 35 years

BACKGROUND

Previous research has indicated a unique profile of executive function (EF) in children and adolescents with Down syndrome (DS). However, there is a paucity of research on EF in adults with DS. This study aimed to gain a broader understanding of strengths and weaknesses in EF in DS from 2 to 35 years.

METHOD

Parents of 112 individuals with DS between 2 and 35 years participated in this study. Parents either completed the Behaviour Rating Inventory of Executive Function - for individuals 6+ years - or the Behaviour Rating Inventory of Executive Function Preschool Version - for children 2-5 years.

RESULTS

Results suggest not only overall difficulties but also patterns of strength and weakness within EF for individuals with DS. For the 2 to 5-year-old group, emotional control and shift were relative strengths, planning/organisation and inhibit were intermediate skills, and working memory was a relative weakness. For the 6 to 18-year-old group, emotional control and organisation of materials were relative strengths, inhibit and initiate were intermediate skills, and working memory, monitor, planning/organisation, and shift were relative weaknesses. Most abilities were consistent from 2 to 18 years, except shift, which decreased in preadolescence before beginning to recover in adolescence. Across the full age range (2-35 years), composite scores indicated quadratic trends in inhibit, working memory, and planning/organisation, and a cubic trend in shift, with EF abilities generally declining in middle childhood before recovering in adulthood.

CONCLUSIONS

This study extends previous research on EF in DS by providing an initial description of EF profiles across the lifespan. More longitudinal and behavioural research is needed to further characterise the development of EF in DS.

Executive functioning in Cornelia de Lange syndrome: domain asynchrony and age-related performance

BACKGROUND

The aim of this study was to examine executive functioning in adolescents and adults with Cornelia de Lange syndrome (CdLS) to identify a syndrome and age-related profile of cognitive impairment.

METHODS

Participants were 24 individuals with CdLS aged 13-42 years (M = 22; SD = 8.98), and a comparable contrast group of 21 individuals with Down syndrome (DS) aged 15-33 years (M = 24; SD = 5.82). Measures were selected to test verbal and visual fluency, inhibition, perseverance/flexibility, and working memory and comprised both questionnaire and performance tests.

RESULTS

Individuals with CdLS showed significantly greater impairment on tasks requiring flexibility and inhibition (rule switch) and on forwards span capacity. These impairments were also reported in the parent/carer-rated questionnaire measures. Backwards Digit Span was significantly negatively correlated with chronological age in CdLS, indicating increased deficits with age. This was not identified in individuals with DS.

CONCLUSIONS

The relative deficits in executive functioning task performance are important in understanding the behavioural phenotype of CdLS. Prospective longitudinal follow-up is required to examine further the changes in executive functioning with age and if these map onto observed changes in behaviour in CdLS. Links with recent research indicating heightened responses to oxidative stress in CdLS may also be important.

A Multi-Method Investigation of Pragmatic Development in Individuals With Down Syndrome

This longitudinal study examined pragmatic language in boys and girls with Down syndrome (DS) at up to three time points, using parent report, standardized and direct assessments. We also explored relationships among theory of mind, executive function, nonverbal mental age, receptive and expressive vocabulary, grammatical complexity, and pragmatic competence. Controlling for cognitive and language abilities, children with DS demonstrated greater difficulty than younger typically developing controls on parent report and standardized assessments, but only girls with DS differed on direct assessments. Further, pragmatic skills of individuals with DS developed at a delayed rate relative to controls. Some sex-specific patterns of pragmatic impairments emerged. Theory of mind and executive function both correlated with pragmatic competence. Clinical and theoretical implications are discussed.

Repetitive Behaviours and Restricted Interests in Individuals with Down Syndrome-One Way of Managing Their World?

This paper argues that the repetitive behaviour and restrictive interests (RBRI) displayed by individuals with Down syndrome have mostly positive functions. However, as research has developed from interests in Obsessional Compulsive Disorder or Autistic Spectrum Disorder, unfortunately a view has arisen that RBRI in individuals with Down syndrome are also likely to be pathological. This is particularly the case in adults. The paper reviews: (a) measures employed and the perspectives that have been used; (b) the development in typically developing individuals, those with Down syndrome, and those with other conditions associated with intellectual disability; (c) positive and possible negative effects of RBRI; and (d) the need for more research. The conclusion is that, for their level of development, RBRI are helpful for most individuals with Down syndrome.

Outcome Measures for Clinical Trials in Down Syndrome

Increasingly individuals with intellectual and developmental disabilities, including Down syndrome, are being targeted for clinical trials. However, a challenge exists in effectively evaluating the outcomes of these new pharmacological interventions. Few empirically evaluated, psychometrically sound outcome measures appropriate for use in clinical trials with individuals with Down syndrome have been identified. To address this challenge, the National Institutes of Health (NIH) assembled leading clinicians and scientists to review existing measures and identify those that currently are appropriate for trials; those that may be appropriate after expansion of age range addition of easier items, and/or downward extension of psychometric norms; and areas where new measures need to be developed. This article focuses on measures in the areas of cognition and behavior.

Training spatial-simultaneous working memory in individuals with Down syndrome

Recent studies have suggested that the spatial-simultaneous component of working memory (WM), which is involved when stimuli are presented simultaneously, is selectively impaired in individuals with Down syndrome (DS). The main objective of the present study was to examine whether WM performance can be enhanced in individuals with DS by analyzing the immediate and maintenance effects of a training program. For this purpose, 61 individuals with DS were randomly assigned to three groups: one trained on simultaneous components of visuospatial WM; one serving as an active control group, that completed activities on vocabulary; and one serving as a passive control group, that only attended the pre- and post-test and follow-up assessments. The efficacy of the training was analyzed in terms of specific (spatial-simultaneous WM tasks), near transfer (spatial-sequential and verbal WM tasks), far transfer (spatial abilities, everyday competences), and maintenance effects (with a follow-up at 1 month). The results showed an overall significant effect on the WM on the group receiving the training. The benefit was generally specific, however, with some transfer to other WM tasks, but only in the immediate (post-test) assessment.

[Behaviour problems of children with Down syndrome in preschool-age - Results from the Heidelberg Down syndrome study]

Aims

We report on the frequency and the correlations of behaviour problems among children with Down syndrome in preschool-age.

Method

As part of a longitudinal study 48 mothers of children with Down syndrome completed the German version of the “Strengths and Difficulties Questionnaire” (SDQ-D) and the Parenting Stress Inventory (PSI). The mothers were asked to fill out the questionnaires when the children had a mean age of five years. The results were compared to norms from children with typical development.

Results

Thirty per cent of the children with Down syndrome were rated as abnormal. Specifically, mean scores indicating problems with children of the same age and hyperactivity were elevated. A regression analysis predicting the total problem score of the SDQ-D revealed maternal educational level, optimistic attitude, and subjective parental stress at the age of one year and the degree of behavioural abnormalities at the age of three years as significant influential factors.

Conclusion

Early intervention for Down syndrome children should include supporting parenting competence and coping skills in order to prevent behaviour problems.

A note on motor skill acquisition in mild and moderate Down syndrome individuals

This study investigated the acquisition of a serial motor skill in individuals with Down syndrome with two levels of handicap, mild group (mean age = 14.5 years, SD = 2.3, 7 individuals) and moderate group (mean age = 15.2 years, SD = 3.2, 7 individuals). The task involved single-arm sequential movements to five. The measures to access performance were overall sequence error, reaction time, and total movement time. To evaluate action program, formation variability of sequencing and relative timing variability were considered. Although there was no clear practice effect, the results showed that the level of handicap led to different strategies to plan and control the actions. The moderate group presented a less stable action program expressed in the variability in sequencing and timing. Their longer reaction times also suggest a heavy demand on central processing in accord with the one-target advantage hypothesis and also due to memory deficits to select and plan movements.

Response abilities of children with Down Syndrome and other intellectual developmental disorders

Efficiency with which a task is performed results from the precise timing and force with which the task is executed. We aimed at assessing the influence of change in task constructs on the response abilities of children who are known to have impaired perceptual motor control. To answer this question, we assessed the response abilities in terms of response time(RT) and response force(RF) among children with Down Syndrome(DS), intellectual developmental disorders(IDD) and those who are typically developing. A response analyzer was used to assess their response abilities across a variety of task constructs namely while performing a simple response task, dual task (i.e. passive and active dual tasks), force modulation task and choice response task. Across all tasks, it was seen that their RT increased while RF decreased as the tasks became more complex in nature. The number of participants in the DS and IDD group diminished as the task complexity increased, reflecting their inherent difficulty in learning new tasks and executing a common expected response under different task conditions. The response abilities of the DS and IDD group was comparable across tasks and varied significantly from the TDC group. The study enables us to understand the influence of task difficulties on the response abilities and participation across groups of children with and without disabilities. The results of the study necessitate the need to evaluate and find methods to train the response abilities of children with DS and IDD, which has considerable implications towards the performance of their daily life skills.

Differential Brain, Cognitive and Motor Profiles Associated with Partial Trisomy. Modeling Down Syndrome in Mice

We hypothesize that the trisomy 21 (Down syndrome) is the additive and interactive outcome of the triple copy of different regions of HSA21. Because of the small number of patients with partial trisomy 21, we addressed the question in the Mouse in which three chromosomal regions located on MMU10, MMU17 and MMU16 carries almost all the HSA21 homologs. Male mice from four segmental trisomic strains covering the D21S17-ETS2 (syntenic to MMU16) were examined with an exhaustive battery of cognitive tests, motor tasks and MRI and compared with TS65Dn that encompasses D21S17-ETS2. None of the four strains gather all the impairments (measured by the effect size) of TS65Dn strain. The 152F7 strain was close to TS65Dn for motor behavior and reference memory and the three other strains 230E8, 141G6 and 285E6 for working memory. Episodic memory was impaired only in strain 285E6. The hippocampus and cerebellum reduced sizes that were seen in all the strains indicate that trisomy 21 is not only a hippocampus syndrome but that it results from abnormal interactions between the two structures.

Executive function and academic achievement in primary - grade students with Down syndrome

BACKGROUND

Executive function (EF) plays a critical role in academic outcomes in typically developing children, but the contribution of EF to academic performance in Down syndrome (DS) is less well understood. This study evaluated differences in early academic foundations between primary school aged children with DS and non-verbal mental-age matched typically developing (TD) children. Additionally, the contribution of EF domains to academic outcomes was evaluated in each group.

METHOD

Participants with DS (n = 29) and mental-age matched TD participants (n = 23) were administered the Woodcock Johnson- III NU Tests of Academic Achievement, as well as a laboratory-based EF battery, including measures of working memory, shifting, inhibition and object-planning.

RESULTS

Findings indicated a difference in early academic foundations profile between children with DS and mental-age matched TD children. Patterns of EF contributions towards academic outcomes were also observed across groups.

CONCLUSIONS

Aspects of EF are critical to academic achievement in DS but differentially so relative to typical development. Implications for educational instruction are discussed.

Learning potential and cognitive abilities in preschool boys with fragile X and Down syndrome

BACKGROUND

Enhancing cognitive abilities is relevant when devising treatment plans.

AIMS

This study examined the performance of preschool boys with Down syndrome and fragile X syndrome in cognitive tasks (e.g., nonverbal reasoning and short-term memory), as well as in improving cognitive functions by means of a learning potential methodology.

METHODS AND PROCEDURES

The basic scales corresponding to the Skills and Learning Potential Preschool Scale were administered to children with Down syndrome and others with fragile X syndrome, matched for chronological age and nonverbal cognitive development level.

RESULTS

The fragile X syndrome group showed stronger performance on short-term memory tasks than the Down syndrome group prior to intervention, with no differences recorded in nonverbal reasoning tasks. In addition, both groups' cognitive performance improved significantly between pre- and post-intervention. However, learning potential relative to auditory memory was limited in both groups, and for rule-based categorization in Down syndrome children.

CONCLUSION

The scale offered the opportunity to assess young children's abilities and identify the degree of cognitive modifiability. Furthermore, factors that may potentially affect the children's performance before and during learning potential assessment are discussed.

The relationship between sound-shape matching and cognitive ability in adults with Down syndrome

Down syndrome (DS), the most common genetic cause of intellectual disability, is characterised by a pattern of cognitive deficits hypothesised as relating to later developing neural systems. Multisensory integration (MSI) has been shown to benefit cognitive performance on numerous tasks in the typically developing population and is implicated in the early development of various cognitive processes. Given these developmental links of both MSI and DS it is important to determine the relationship between MSI and DS. This study aimed to characterise sound-shape matching performance in young adults with DS as an indicator of MSI (correct response rate around 90% in typically developing individuals). We further investigated the relationship between task performance and estimated cognitive ability (verbal and non-verbal) in addition to everyday adaptive behavior skills. Those answering correctly (72.5%) scored significantly higher across cognitive and adaptive behavior measures compared to those answering incorrectly. Furthermore, 57.1% of individuals with estimated cognitive ability scores below the median value answered correctly compared to 89.5% of individuals scoring above the median, with similar values found for adaptive behavior skills (57.9% vs 94.4%). This preliminary finding suggests sound-shape matching deficits are relatively common in DS but may be restricted to individuals of lower ability as opposed to being a general characteristic of DS. Further studies investigating aspects of MSI across a range of modalities are necessary to fully characterise the nature of MSI in DS and to explore underlying neural correlates and mechanisms.

Cross-syndrome comparison of real-world executive functioning and problem solving using a new problem-solving questionnaire

BACKGROUND

Individuals with neurodevelopmental disorders like Williams syndrome and Down syndrome exhibit executive function impairments on experimental tasks (Lanfranchi, Jerman, Dal Pont, Alberti, & Vianello, 2010; Menghini, Addona, Costanzo, & Vicari, 2010), but the way that they use executive functioning for problem solving in everyday life has not hitherto been explored. The study aim is to understand cross-syndrome characteristics of everyday executive functioning and problem solving.

METHODS

Parents/carers of individuals with Williams syndrome (n=47) or Down syndrome (n=31) of a similar chronological age (m=17 years 4 months and 18 years respectively) as well as those of a group of younger typically developing children (n=34; m=8years 3 months) completed two questionnaires: the Behavior Rating Inventory of Executive Function (BRIEF; Gioia, Isquith, Guy, & Kenworthy, 2000) and a novel Problem-Solving Questionnaire.

RESULTS

The rated likelihood of reaching a solution in a problem solving situation was lower for both syndromic groups than the typical group, and lower still for the Williams syndrome group than the Down syndrome group. The proportion of group members meeting the criterion for clinical significance on the BRIEF was also highest for the Williams syndrome group. While changing response, avoiding losing focus and maintaining perseverance were important for problem-solving success in all groups, asking for help and avoiding becoming emotional were also important for the Down syndrome and Williams syndrome groups respectively. Keeping possessions in order was a relative strength amongst BRIEF scales for the Down syndrome group.

CONCLUSION

Results suggest that individuals with Down syndrome tend to use compensatory strategies for problem solving (asking for help and potentially, keeping items well ordered), while for individuals with Williams syndrome, emotional reactions disrupt their problem-solving skills. This paper highlights the importance of identifying syndrome-specific problem-solving strengths and difficulties to improve effective functioning in everyday life.

Impact of maladaptive behavior on school function in Down syndrome

BACKGROUND/AIMS

Individuals with Down syndrome (DS) are at an increased risk for certain maladaptive behaviors. This study characterized maladaptive behavior in school-aged children with DS and examined the extent to which maladaptive behaviors are associated with school function.

METHODS AND PROCEDURES

Participants were 24 students with DS [mean nonverbal mental age (NVMA)=43.83months; mean chronological age (CA)=77.58months] who completed the Leiter Scales of Performance- Revised (Leiter-R; Roid & Miller, 1997). Their teachers completed the Behavior Assessment Scales for Children Version 2 (Reynolds & Kamphaus, 2004), and the School Function Assessment (Coster et al., 1998), measures of maladaptive and adaptive behavior as observed in the school setting.

RESULTS

Findings reveal a maladaptive behavior profile of elevated areas including Aggression, Attention Problems, and Somatization. When examining the association between maladaptive behavior and school function, multivariate regression results indicated a significant association between Aggression and Compliance, and Attention Problems and Task Completion.

CONCLUSIONS AND IMPLICATIONS

Results underscore the importance of developing training for educators regarding the potential impact of maladaptive behavior on school function for students with Down syndrome.

The LonDownS adult cognitive assessment to study cognitive abilities and decline in Down syndrome

Background: Down syndrome (DS), the most common genetic cause of intellectual disability, is associated with an ultra-high risk of developing Alzheimer’s disease. However, there is individual variability in the onset of clinical dementia and in baseline cognitive abilities prior to decline, particularly in memory, executive functioning, and motor coordination. The LonDownS Consortium aims to determine risk and protective factors for the development of dementia and factors relating to cognitive abilities in people with DS. Here we describe our cognitive test battery and related informant measures along with reporting data from our baseline cognitive and informant assessments.

Methods: We developed a cognitive test battery to assess general abilities, memory, executive function, and motor coordination abilities in adults with DS, with informant ratings of similar domains also collected, designed to allow for data on a broad range of participants. Participants (n=305) had a range of ages and abilities, and included adults with and without a clinical diagnosis of dementia.

Results: Results suggest the battery is suitable for the majority of adults with DS, although approximately half the adults with dementia were unable to undertake any cognitive task. Many test outcomes showed a range of scores with low floor and ceiling effects. Non-verbal age-adjusted IQ scores had lower floor effects than verbal IQ scores. Before the onset of any cognitive decline, females aged 16-35 showed better verbal abilities compared to males. We also identified clusters of cognitive test scores within our battery related to visuospatial memory, motor coordination, language abilities, and processing speed / sustained attention.

Conclusions: Our further studies will use baseline and longitudinal assessments to explore factors influencing cognitive abilities and cognitive decline related to ageing and onset of dementia in adults with DS.

The effects of assisted cycling therapy (ACT) and voluntary cycling on reaction time and measures of executive function in adolescents with Down syndrome

BACKGROUND

Reports of positive effects of aerobic exercise on cognitive function in persons with Down syndrome are extremely limited. However, a novel exercise intervention, termed assisted cycling therapy (ACT), has resulted in acutely improved cognitive planning ability and reaction times as well as improved cognitive planning after 8 weeks of ACT in adolescents and young adults with Down syndrome. Here, we report the effects of 8 weeks of ACT on reaction time, set-shifting, inhibition and language fluency in adolescents with Down syndrome.

METHODS

Adolescents with Down syndrome (age: ~18 years) were randomly assigned to 8 weeks of ACT (n = 17) or voluntary cycling (VC: n = 16), and a convenience sample (n = 11) was assigned to be an inactive comparison group (NC: n = 11). During ACT, the cycling cadence of the participants was augmented to an average cadence that was 80% faster than the voluntary cadence of the VC group. The increase in cadence was achieved with an electric motor in the stationary bicycle. Reaction time, set-shifting, inhibition and language fluency were assessed before and after 8 weeks of intervention.

RESULTS

Power output and heart rates of the ACT and VC groups were almost identical, but the ACT cadence was significantly faster. The ACT group, but not the VC or NC groups, showed significantly improved reactions times (Hedges' g = -0.42) and inhibitory control (g = 0.18). Only the VC group showed improved set-shifting ability (g = 0.57). The ACT and VC groups displayed improved semantic language fluency (g = 0.25, g = 0.22, respectively).

DISCUSSIONS

These and previous results support the hypothesis of increased neuroplasticity and prefrontal cortex function following ACT and, to a smaller extent, following VC. Both ACT and VC appear to be associated with cortical benefits, but based on current and previous results, ACT seems to maximize the benefits.

The impact of behavioural executive functioning and intelligence on math abilities in children with intellectual disabilities

BACKGROUND

Little is known about the role of behavioural executive functioning (EF) skills and level of intelligence (IQ) on math abilities in children with mild to borderline intellectual disabilities.

METHOD

Teachers of 63 children attending a school for special education (age: 10 to 13 years; IQ: 50 to 85) filled out a Behaviour Rating Inventory for Executive Function for each student. Furthermore, students took a standardised national composite math test and a specific math test on measurement and time problems. Information on level of intelligence was gathered through school records. Multiple regression analyses were performed to test direct, moderating and mediating effects of EF and IQ on math performance.

RESULTS

Behavioural problems with working memory and flexibility had a direct negative effect on math outcome, while concurrently, level of intelligence had a positive effect. The effect of IQ on math skills was moderated by problems with inhibition: in children with a clinical level of inhibition problems, there was no effect of level of intelligence on math performance.

CONCLUSIONS

Findings suggest that in students with mild to borderline intellectual disabilities and math difficulties, it is important to address their strengths and weaknesses with respect to EF and adjust instruction and remedial intervention accordingly.

The NIH Toolbox Cognitive Battery for intellectual disabilities: three preliminary studies and future directions

BACKGROUND

Recent advances in understanding molecular and synaptic mechanisms of intellectual disabilities (ID) in fragile X syndrome (FXS) and Down syndrome (DS) through animal models have led to targeted controlled trials with pharmacological agents designed to normalize these underlying mechanisms and improve clinical outcomes. However, several human clinical trials have failed to demonstrate efficacy of these targeted treatments to improve surrogate behavioral endpoints. Because the ultimate index of disease modification in these disorders is amelioration of ID, the validation of cognitive measures for tracking treatment response is essential. Here, we present preliminary research to validate the National Institutes of Health Toolbox Cognitive Battery (NIH-TCB) for ID.

METHODS

We completed three pilot studies of patients with FXS (total n = 63; mean age 19.3 ± 8.3 years, mean mental age 5.3 ± 1.6 years), DS (n = 47; mean age 16.1 ± 6.2, mean mental age 5.4 ± 2.0), and idiopathic ID (IID; n = 16; mean age 16.1 ± 5.0, mean mental age 6.6 ± 2.3) measuring processing speed, executive function, episodic memory, word/letter reading, receptive vocabulary, and working memory using the web-based NIH-TB-CB, addressing feasibility, test-retest reliability, construct validity, ecological validity, and syndrome differences and profiles.

RESULTS

Feasibility was good to excellent (≥80 % of participants with valid scores) for above mental age 4 years for all tests except list sorting (working memory). Test-retest stability was good to excellent, and convergent validity was similar to or better than results obtained from typically developing children in the normal sample for executive function and language measures. Examination of ecological validity revealed moderate to very strong correlations between the NIH-TCB composite and adaptive behavior and full-scale IQ measures. Syndrome/group comparisons demonstrated significant deficits for the FXS and DS groups relative to IID on attention and inhibitory control, a significant reading weakness for FXS, and a receptive vocabulary weakness for DS.

CONCLUSIONS

The NIH-TCB has potential for assessing important dimensions of cognition in persons with ID, and several tests may be useful for tracking response to intervention. However, more extensive psychometric studies, evaluation of the NIH-TCB's sensitivity to change, both developmentally and in the context of treatment, and perhaps establishing links to brain function in these populations, are required to determine the true utility of the battery as a set of outcome measures.

The profile of social functioning in children with Down syndrome

BACKGROUND

Practitioners and researchers have asserted for decades that social functioning is a strength in children with Down syndrome (DS). Nevertheless, some studies have concluded that children with DS may be at greater risk of impaired social functioning compared to typically developing controls. This cross-sectional study explores the profile of social functioning (social capabilities and social problems) in six-year-old children with DS, compares it with that of typically developing children and reveals possible differences in predictors between groups.

METHOD

Parental reports and clinical tests were utilized.

RESULTS

The children with DS had generally weaker social capabilities compared to nonverbal mental age-matched controls, but no significant differences were found for social interactive play, community functioning and prosocial behaviour. No significant differences in predictors for social capabilities between the groups were found. The children with DS had more social problems than the typically developing controls with a similar chronological age and those with a similar nonverbal mental age, but no significant differences in emotional symptoms were found between the children with DS and either comparison group. Vocabulary was a more important predictor of social problems in the children with DS than in the typically developing control groups.

CONCLUSION

Interventions for children with DS should strongly focus on integrating vocabulary skills and social functioning starting at an early age. Implications for Rehabilitation Children with Down syndrome need help and support in social functioning. Systematic training to optimize social capabilities and to prevent social problems should be prioritized. Structured and explicit learning of words important for social interaction with peers and for conflict solutions should be emphasized. Integrated interventions focusing on social functioning and vocabulary should begin in preschool to prepare children for participation in mainstream education.

Developing an Informant Questionnaire for Cognitive Abilities in Down Syndrome: The Cognitive Scale for Down Syndrome (CS-DS)

Down syndrome (DS) is the most common genetic cause of intellectual disability (ID). Abilities relating to executive function, memory and language are particularly affected in DS, although there is a large variability across individuals. People with DS also show an increased risk of developing dementia. While assessment batteries have been developed for adults with DS to assess cognitive abilities, these batteries may not be suitable for those with more severe IDs, dementia, or visual / hearing difficulties. Here we report the development of an informant rated questionnaire, the Cognitive Scale for Down Syndrome (CS-DS), which focuses on everyday abilities relating to executive function, memory and language, and is suitable for assessing these abilities in all adults with DS regardless of cognitive ability. Complete questionnaires were collected about 128 individuals with DS. After final question selection we found high internal consistency scores across the total questionnaire and within the executive function, memory and language domains. CS-DS scores showed a wide range, with minimal floor and ceiling effects. We found high interrater (n = 55) and test retest (n = 36) intraclass correlations. CS-DS scores were significantly lower in those aged 41+ with significant cognitive decline compared to those without decline. Across all adults without cognitive decline, CS-DS scores correlated significantly to measures of general abilities. Exploratory factor analysis suggested five factors within the scale, relating to memory, self-regulation / inhibition, self-direction / initiation, communication, and focussing attention. The CS-DS therefore shows good interrater and test retest reliability, and appears to be a valid and suitable informant rating tool for assessing everyday cognitive abilities in a wide range of individuals with DS. Such a questionnaire may be a useful outcome measure for intervention studies to assess improvements to cognition, in addition to detecting dementia-related cognitive decline. The CS-DS may also be a useful tool for other populations with ID.

Executive Function and Ambiguous Sentence Comprehension

PURPOSE

Sentence comprehension is a critical skill in today's literate society. Recent evidence suggests that processing and comprehending language taps cognitive as well as linguistic abilities, a finding that has critical import for clinicians who have clients with language disorders. To promote awareness of the impact of cognition, especially executive function (EF) and working memory (WM), this opinion article presents current views of how sentences are processed and links the various steps of the process to specific EF and WM subcomponents.

METHOD

The article focuses on ambiguous sentences, pointing out the similar types of processing needed when resolving an ambiguity and performing EF tasks.

RESULTS

We discuss the potential overlap between the neurobiology of sentence processing and EF and the evidence supporting a link between EF and sentence processes.

CONCLUSION

Awareness of the potential role of EF and WM in sentence comprehension will help clinicians be more aware of potential cognitive-linguistic deficits in their clients. Future research will help to clarify the link between EF and sentence comprehension.

Gait dyspraxia as a clinical marker of cognitive decline in Down syndrome: A review of theory and proposed mechanisms

Down syndrome (DS) is the most common genetic cause of intellectual disability in children. With aging, DS is associated with an increased risk for Alzheimer's disease (AD). The development of AD neuropathology in individuals with DS can result in further disturbances in cognition and behavior and may significantly exacerbate caregiver burden. Early detection may allow for appropriate preparation by caregivers. Recent literature suggests that declines in gait may serve as an early marker of AD-related cognitive disorders; however, this relationship has not been examined in individuals with DS. The theory regarding gait dyspraxia and cognitive decline in the general population is reviewed, and potential applications to the population with individuals with DS are highlighted. Challenges and benefits in the line of inquiry are discussed. In particular, it appears that gait declines in aging individuals with DS may be associated with known declines in frontoparietal gray matter, development of AD-related pathology, and white matter losses in tracts critical to motor control. These changes are also potentially related to the cognitive and functional changes often observed during the same chronological period as gait declines in adults with DS. Gait declines may be an early marker of cognitive change, related to the development of underlying AD-related pathology, in individuals with DS. Future investigations in this area may provide insight into the clinical changes associated with development of AD pathology in both the population with DS and the general population, enhancing efforts for optimal patient and caregiver support and propelling investigations regarding safety/quality of life interventions and disease-modifying interventions.

A Novel Analog Reasoning Paradigm: New Insights in Intellectually Disabled Patients

Background

Intellectual Disability (ID) is characterized by deficits in intellectual functions such as reasoning, problem-solving, planning, abstract thinking, judgment, and learning. As new avenues are emerging for treatment of genetically determined ID (such as Down’s syndrome or Fragile X syndrome), it is necessary to identify objective reliable and sensitive outcome measures for use in clinical trials.

Objective

We developed a novel visual analogical reasoning paradigm, inspired by the Progressive Raven’s Matrices, but appropriate for Intellectually Disabled patients. This new paradigm assesses reasoning and inhibition abilities in ID patients.

Methods

We performed behavioural analyses for this task (with a reaction time and error rate analysis, Study 1) in 96 healthy controls (adults and typically developed children older than 4) and 41 genetically determined ID patients (Fragile X syndrome, Down syndrome and ARX mutated patients). In order to establish and quantify the cognitive strategies used to solve the task, we also performed an eye-tracking analysis (Study 2).

Results

Down syndrome, ARX and Fragile X patients were significantly slower and made significantly more errors than chronological age-matched healthy controls. The effect of inhibition on error rate was greater than the matrix complexity effect in ID patients, opposite to findings in adult healthy controls. Interestingly, ID patients were more impaired by inhibition than mental age-matched healthy controls, but not by the matrix complexity. Eye-tracking analysis made it possible to identify the strategy used by the participants to solve the task. Adult healthy controls used a matrix-based strategy, whereas ID patients used a response-based strategy. Furthermore, etiologic-specific reasoning differences were evidenced between ID patients groups.

Conclusion

We suggest that this paradigm, appropriate for ID patients and developmental populations as well as adult healthy controls, provides an objective and quantitative assessment of visual analogical reasoning and cognitive inhibition, enabling testing for the effect of pharmacological or behavioural intervention in these specific populations.

Down Syndrome Developmental Brain Transcriptome Reveals Defective Oligodendrocyte Differentiation and Myelination

Trisomy 21, or Down syndrome (DS), is the most common genetic cause of developmental delay and intellectual disability. To gain insight into the underlying molecular and cellular pathogenesis, we conducted a multi-region transcriptome analysis of DS and euploid control brains spanning from mid-fetal development to adulthood. We found genome-wide alterations in the expression of a large number of genes, many of which exhibited temporal and spatial specificity and were associated with distinct biological processes. In particular, we uncovered co-dysregulation of genes associated with oligodendrocyte differentiation and myelination that were validated via cross-species comparison to Ts65Dn trisomy mice. Furthermore, we show that hypomyelination present in Ts65Dn mice is in part due to cell-autonomous effects of trisomy on oligodendrocyte differentiation and results in slower neocortical action potential transmission. Together, these results identify defects in white matter development and function in DS, and they provide a transcriptional framework for further investigating DS neuropathogenesis.

Recall memory in children with Down syndrome and typically developing peers matched on developmental age

BACKGROUND

Whereas research has indicated that children with Down syndrome (DS) imitate demonstrated actions over short delays, it is presently unknown whether children with DS recall information over lengthy delays at levels comparable with typically developing (TD) children matched on developmental age.

METHOD

In the present research, 10 children with DS and 10 TD children participated in a two-session study to examine basic processes associated with hippocampus-dependent recall memory. At the first session, the researcher demonstrated how to complete a three-step action sequence with novel stimuli; immediate imitation was permitted as an index of encoding. At the second session, recall memory was assessed for previously modelled sequences; children were also presented with two novel three-step control sequences.

RESULTS

The results indicated that group differences were not apparent in the encoding of the events or the forgetting of information over time. Group differences were also not observed when considering the recall of individual target actions at the 1-month delay, although TD children produced more target actions overall at the second session relative to children with DS. Group differences were found when considering memory for temporal order information, such that TD children evidenced recall relative to novel control sequences, whereas children with DS did not.

CONCLUSIONS

These findings suggest that children with DS may have difficulty with mnemonic processes associated with consolidation/storage and/or retrieval processes relative to TD children.

«Cognitus & Moi»: A Computer-Based Cognitive Remediation Program for Children with Intellectual Disability

Attentional, visuospatial, and social cognition deficits have a negative impact on children's adaptative and social competences and, as a result, on their ability to achieve a normal functioning and behavior. Until now and despite the frequency of those deficits, there is a lack of children's specific cognitive remediation tools specifically dedicated to attentional and visuospatial areas. The «Cognitus & Moi» program involves a variety of exercises in a paper and/or pencil (n = 30) or a computerized format (n = 29) and a strategy coaching approach. Each module of «Cognitus & Moi» targets a single impaired cognitive area, within the limits of cognitive domains' overlapping. The little cartoon character named Cognitus, who illustrates the program, is supposed to be very friendly and kind toward children. Cognitus will accompany them throughout the program for an effective and positive reinforcement. The main goal of «Cognitus & Moi» is to adjust to children's difficulties in daily life. Moreover, since the cognitive remediation benefit is complex to apply in daily life, the program is based on a metacognitive strategy. After a complete neuropsychological assessment and a psychoeducational session (with the child and the parents), 16 1-h-sessions of cognitive remediation with the therapist are proposed. Each session is composed of three parts: (1) computerized tasks focusing on specific attentional or visuospatial components (20 min). The attentional module targets hearing, visual, and divided attention. A double attention task is also proposed. The visuospatial module targets eye tracking and gaze direction, spatial orientation, visuospatial memory and construction, and mental imagery; (2) pen and paper tasks focusing on the same processes (20 min) and a facial emotion recognition task; (3) a proposal of a home-based task (during 20 min). Weekly, specific attentional and visuospatial home tasks are proposed to the child and analyzed with the parents and the therapist. Indeed, home exercises are useful to promote the transfer of strategies to daily life and their subsequent automation. The heterogeneity of cognitive deficits in intellectual deficiency necessitates an individualized cognitive remediation therapy. In this regard, «Cognitus & Moi» seems to be a promising tool.

Executive functions among youth with Down Syndrome and co-existing neurobehavioural disorders

BACKGROUND

Executive function (EF) deficits are a recognised component of the cognitive phenotype of youth with Down Syndrome (DS). Recent research in this area emphasises the use of behaviour ratings, such as the Behavior Rating Inventory of Executive Functions-Preschool Version (BRIEF-P), to capture the real-world applications of executive functions. To account for the intellectual functioning of youth with DS, this measure is used out of age range; however, its psychometric properties when used in this fashion are unknown. The goals of this study are to evaluate psychometric characteristics of the BRIEF-P among youth with DS and to examine the pattern of EF strengths/weaknesses in children with DS and co-occurring psychiatric conditions.

METHOD

A total of 188 clinically referred youth with DS, ages 3-13 were rated by their caregivers using the BRIEF-P. These youth were evaluated by a clinician with expertise in DS and were characterised as having no co-occurring behavioural disorder (Typical DS group), co-occurring Autism Spectrum Disorder (DS + ASD) or co-occurring Disruptive Behaviour Disorder (DS + DBD).

RESULTS

An exploratory factor analysis of item-level BRIEF-P data from clinically referred youth with DS supported the theoretically derived three-factor structure originally proposed for the BRIEF-P (Emergent Metacognition, Flexibility and Inhibitory Self-Control); however, the item composition of each factor varied somewhat in comparison to the original structure of the measure. Group comparisons indicate that, while youth with typical DS evidence fewer executive function difficulties across all domains, youth with DS + ASD show the greatest weaknesses in Emergent Metacognition, and youth with DS + DBD show significant difficulties in both Emergent Metacognition and Inhibition.

CONCLUSIONS

These findings offer preliminary support for use of the BRIEF-P with clinically referred youth with Down Syndrome. Some scoring modifications may be necessary if the theoretically derived index scores are to be used with this population. BRIEF-P scores may offer an empirical basis for differentiating DS youth with varying behavioural profiles.

Assessment of Cognitive Scales to Examine Memory, Executive Function and Language in Individuals with Down Syndrome: Implications of a 6-month Observational Study

Down syndrome (DS) is the most commonly identifiable genetic form of intellectual disability. Individuals with DS have considerable deficits in intellectual functioning (i.e., low intellectual quotient, delayed learning and/or impaired language development) and adaptive behavior. Previous pharmacological studies in this population have been limited by a lack of appropriate endpoints that accurately measured change in cognitive and functional abilities. Therefore, the current longitudinal observational study assessed the suitability and reliability of existing cognitive scales to determine which tools would be the most effective in future interventional clinical studies. Subtests of the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), Cambridge Neuropsychological Test Automated Battery (CANTAB), and Clinical Evaluation of Language Fundamentals-Preschool-2 (CELF-P-2), and the Observer Memory Questionnaire-Parent Form (OMQ-PF), Behavior Rating Inventory of Executive Function®-Preschool Version (BRIEF-P) and Leiter International Performance Scale-Revised were assessed. The results reported here have contributed to the optimization of trial design and endpoint selection for the Phase 2 study of a new selective negative allosteric modulator of the GABAA receptor α5-subtype (Basmisanil), and can be applied to other studies in the DS population.

Semantic Verbal Fluency Pattern, Dementia Rating Scores and Adaptive Behavior Correlate With Plasma Aβ42 Concentrations in Down Syndrome Young Adults

Down syndrome (DS) is an intellectual disability (ID) disorder in which language and specifically, verbal fluency are strongly impaired domains; nearly all adults show neuropathology of Alzheimer’s disease (AD), including amyloid deposition by their fifth decade of life. In the general population, verbal fluency deficits are considered a strong AD predictor being the semantic verbal fluency task (SVFT) a useful tool for enhancing early diagnostic. However, there is a lack of information about the association between the semantic verbal fluency pattern (SVFP) and the biological amyloidosis markers in DS. In the current study, we used the SVFT in young adults with DS to characterize their SVFP, assessing total generated words, clustering, and switching. We then explored its association with early indicators of dementia, adaptive behavior and amyloidosis biomarkers, using the Dementia Questionnaire for Persons with Intellectual Disability (DMR), the Adaptive Behavior Assessment System-Second Edition (ABAS-II), and plasma levels of Aβ peptides (Aβ₄₀ and Aβ₄₂), as a potent biomarker of AD. In DS, worse performance in SVFT and poorer communication skills were associated with higher plasma Aβ₄₂ concentrations, a higher DMR score and impaired communication skills (ABAS–II). The total word production and switching ability in SVFT were good indicators of plasma Aβ₄₂ concentration. In conclusion, we propose the SVFT as a good screening test for early detection of dementia and amyloidosis in young adults with DS.

Everyday executive functions in Down syndrome from early childhood to young adulthood: evidence for both unique and shared characteristics compared to youth with sex chromosome trisomy (XXX and XXY)

Executive functions (EF) are thought to be impaired in Down syndrome (DS) and sex chromosome trisomy (Klinefelter and Trisomy X syndromes; +1X). However, the syndromic specificity and developmental trajectories associated with EF difficulties in these groups are poorly understood. The current investigation (a) compared everyday EF difficulties in youth with DS, +1X, and typical development (TD); and (b) examined relations between age and EF difficulties in these two groups and a TD control group cross-sectionally. Study 1 investigated the syndromic specificity of EF profiles on the Behavior Rating Inventory of Executive Function (BRIEF) in DS (n = 30), +1X (n = 30), and a TD group (n = 30), ages 5–18 years. Study 2 examined age effects on EF in the same cross-sectional sample of participants included in Study 1. Study 3 sought to replicate Study 2's findings for DS by examining age-EF relations in a large independent sample of youth with DS (n = 85) and TD (n = 43), ages 4–24 years. Study 1 found evidence for both unique and shared EF impairments for the DS and +1X groups. Most notably, youth with +1X had relatively uniform EF impairments on the BRIEF scales, while the DS group showed an uneven BRIEF profile with relative strengths and weaknesses. Studies 2 and 3 provided support for fairly similar age-EF relations in the DS and TD groups. In contrast, for the +1X group, findings were mixed; 6 BRIEF scales showed similar age-EF relations to the TD group and 2 showed greater EF difficulties at older ages for +1X. These findings will be discussed within the context of efforts to identify syndrome specific cognitive-behavioral profiles for youth with different genetic syndromes in order to inform basic science investigations into the etiology of EF difficulties in these groups and to develop treatment approaches that are tailored to the needs of these groups.

Improving working memory abilities in individuals with Down syndrome: a treatment case study

Working memory (WM) skills of individuals with Down's syndrome (DS) tend to be very poor compared to typically developing children of similar mental age. In particular, research has found that in individuals with DS visuo-spatial WM is better preserved than verbal WM. This study investigated whether it is possible to train short-term memory (STM) and WM abilities in individuals with DS. The cases of two teenage children are reported: EH, 17 years and 3 months, and AS, 15 years and 11 months. A school-based treatment targeting visuo-spatial WM was given to EH and AS for six weeks. Both prior to and after the treatment, they completed a set of assessments to measure WM abilities and their performance was compared with younger typically developing non-verbal mental age controls. The results showed that the trained participants improved their performance in some of the trained and non-trained WM tasks proposed, especially with regard to the tasks assessing visuo-spatial WM abilities. These findings are discussed on the basis of their theoretical, educational, and clinical implications.

Improvements in manual dexterity relate to improvements in cognitive planning after assisted cycling therapy (ACT) in adolescents with down syndrome

We have previously reported beneficial effects of acute (i.e., single session) Assisted Cycling Therapy (ACT) on manual dexterity and cognitive planning ability in adolescents with Down syndrome (DS). In the present study, we report the chronic effects of eight weeks of ACT, voluntary cycling (VC), and no cycling (NC), on the same measures in adolescents with DS. Participants completed 8 weeks of ACT, VC, or NC. Those in the ACT and VC groups completed 30min sessions three times per week on a stationary bicycle. During ACT, the mechanical motor of the bicycle augmented the cadence to a rate which was on average 79% faster than the voluntary cadence. During VC, the participants pedaled at a self-selected rate. Unimanual dexterity scores as measured with the Purdue Pegboard test (PPT) improved significantly more for the ACT and VC groups compared to the NC group. ACT lead to greater improvements than VC and NC in the assembly sub-test, which is a task that requires more advanced temporal and spatial processing. The ACT group improved significantly more than the VC group and non-significantly more than the NC group in cognitive planning ability as measured by the Tower of London test (ToL). There were also significant correlations between the assembly subtest of the PPT and all measures of the ToL. These correlations were stronger during post-testing than pre-testing. Pre-post changes in the combined PPT score and ToL number of correct moves correlated positively in the ACT group. These results support the efficacy of the salutary effects of ACT on global fine motor function and executive function in DS. Additionally, the performance on complex bimanual dexterity tasks appears to be related to the capacity of cognitive planning ability. This research has important implications for persons with movement deficits that affect activities of daily living.

Numerical skills in children with Down syndrome. Can they be improved?

The present study aims to explore the impact of a numerical skills training program on the basic mathematical skills and logical thinking in children with Down syndrome (DS). The training program was built specifically for children with DS, bearing the strengths and weaknesses of their particular cognitive profile in mind. Two groups of children with DS took part in the study. All children were tested before and after the training on measures of numerical skills and logical thinking. One group of 27 children was trained in numerical skills twice a week for 2 months, for about 30min per session. A control group of 9 children was not involved in any training session. After training, children in the intervention group performed better in numerical tests, while those in the control group did not. These results suggest that our training program is both feasible and effective for children with Down syndrome.

Building an adaptive brain across development: targets for neurorehabilitation must begin in infancy

Much progress has been made toward behavioral and pharmacological intervention in intellectual disability, which was once thought too difficult to treat. Down syndrome (DS) research has shown rapid advances, and clinical trials are currently underway, with more on the horizon. Here, we review the literature on the emergent profile of cognitive development in DS, emphasizing that treatment approaches must consider how some "end state" impairments, such as language deficits, may develop from early alterations in neural systems beginning in infancy. Specifically, we highlight evidence suggesting that there are pre- and early postnatal alterations in brain structure and function in DS, resulting in disturbed network function across development. We stress that these early alterations are likely amplified by Alzheimer's disease (AD) progression and poor sleep. Focusing on three network hubs (prefrontal cortex, hippocampus, and cerebellum), we discuss how these regions may relate to evolving deficits in cognitive function in individuals with DS, and to their language profile in particular.

Relationship between motor skill competency and executive function in children with Down's syndrome

BACKGROUND

Previous studies suggest that children with Down's syndrome (DS), a genetically based neurodevelopmental disorder, demonstrate motor problems and cognitive deficits. The first aim of this study was to examine motor skills and executive functions (EFs) in school-age children with DS. The second aim was to investigate the relationship between these two performance domains.

METHODS

The Test of Gross Motor Development (TGMD-2), the Movement Assessment Battery Children-2 checklist (MABC2-checklist) and the Trail-Making Test for young children (Trails-P) were used to assess motor and cognitive performances of 18 children (11 boys, 7 girls) with DS aged between 7 and 11 years (9.06 ± 0.96) and an age- and sex-matched sample of 18 typically developing (TD) children (11 boys, 7 girls; 8.99 ± 0.93).

RESULTS

Individuals with DS showed the expected difficulties in attentional control, response suppression and distraction, as well as in locomotor and object control skills, as indicated by poorer performance than TD individuals. Motor performance (bottom-up as well as top-down measures) and EF correlated positively, with regard to the group with DS only though. In the most complex task (distraction), the children of the DS group achieving lower locomotor scores showed lower efficacy scores on the Trails-P. Additionally, strong relationships were found for the perspective of teachers on all sections of the MABC2-Checklist and EF.

CONCLUSION

The findings from this study suggest that children with DS are not only impaired in higher-order EF, but showing also deficits in locomotor and object control skills. This study stresses the importance of early interventions facilitating cognitive abilities and motor skills.

Improving spatial-simultaneous working memory in Down syndrome: effect of a training program led by parents instead of an expert

Recent studies have suggested that the visuospatial component of working memory (WM) is selectively impaired in individuals with Down syndrome (DS), the deficit relating specifically to the spatial-simultaneous component, which is involved when stimuli are presented simultaneously. The present study aimed to analyze the effects of a computer-based program for training the spatial-simultaneous component of WM in terms of: specific effects (on spatial-simultaneous WM tasks); near and far transfer effects (on spatial-sequential and visuospatial abilities, and everyday memory tasks); and maintenance effects (1 month after the training). A comparison was drawn between the results obtained when the training was led by parents at home as opposed to an expert in psychology. Thirty-nine children and adolescents with DS were allocated to one of two groups: the training was administered by an expert in one, and by appropriately instructed parents in the other. The training was administered individually twice a week for a month, in eight sessions lasting approximately 30 min each. Our participants' performance improved after the training, and these results were maintained a month later in both groups. Overall, our findings suggest that spatial-simultaneous WM performance can be improved, obtaining specific and transfer gains; above all, it seems that, with adequate support, parents could effectively administer a WM training to their child.

Negative life events predict performance on an executive function task in young adults with developmental disabilities

BACKGROUND

Recent research with typically developing children indicates that chronic stress can be detrimental to the development of executive function. This study extends this work to individuals with developmental disabilities and examines the longitudinal relationship between an indicator of chronic stress, negative life events, and performance on a task of executive function within a group of 30 individuals with early identified developmental disabilities.

METHODS

Multilevel modelling was used to analyse the relationship between cumulative negative life events and response time on a Flanker task.

RESULTS

As hypothesized, individuals who had experienced more cumulative negative life events in their families demonstrated longer response time, an indicator of less efficient executive function.

CONCLUSIONS

The association between cumulative negative life events and executive function for children with developmental disabilities suggests the prominent role of the environment for development in this domain. These findings also suggest the importance of providing services, resources, and interventions that will help families adaptively cope with stressful circumstances.

The association between a single bout of moderate physical activity and executive function in young adults with Down syndrome: a preliminary study

BACKGROUND

This study was aimed at investigating the impact of a single exercise intervention on executive function in young adults with Down syndrome (DS).

METHODS

Considering the relations among executive function, physical and mental health and early onset of Alzheimer's disease in this population, we tested three components of executive function (e.g. choice-response time, attention shifting and inhibition) that have been shown to be impaired in previous studies. Ten persons with DS were assigned to an exercise group, who walked on a treadmill for 20 min at moderate intensity and ten additional persons with DS were assigned to an attentional control group, who watched a video. Measures of executive function were tested pre and post interventions.

RESULTS

These results showed non-significant improvements in choice-response time (P = 0.32) and attention shifting (P = 0.13) but a statistically significant improvement in inhibition (P = 0.03) after the exercise intervention.

CONCLUSIONS

Given the improved inhibition ability, exercise may be an effective intervention, even in a signal session. However, only a few studies have focused on this topic. Based on theoretical models linking exercise to executive function, we proposed that exercise may increase arousal status or enhance neural transmission. Hence, future work is needed to examine the exact mechanism in the relationship between exercise and executive function for individuals with DS.

A new cognitive evaluation battery for Down syndrome and its relevance for clinical trials

The recent prospect of pharmaceutical interventions for cognitive impairment of Down syndrome (DS) has boosted a number of clinical trials in this population. However, running the trials has raised some methodological challenges and questioned the prevailing methodology used to evaluate cognitive functioning of DS individuals. This is usually achieved by comparing DS individuals to matched healthy controls of the same mental age. We propose a new tool, the TESDAD Battery that uses comparison with age-matched typically developed adults. This is an advantageous method for probing the clinical efficacy of DS therapies, allowing the interpretation and prediction of functional outcomes in clinical trials. In our DS population the TESDAD battery permitted a quantitative assessment of cognitive defects, which indicated language dysfunction and deficits in executive function, as the most important contributors to other cognitive and adaptive behavior outcomes as predictors of functional change in DS. Concretely, auditory comprehension and functional academics showed the highest potential as end-point measures of therapeutic intervention for clinical trials: the former as a cognitive key target for therapeutic intervention, and the latter as a primary functional outcome measure of clinical efficacy. Our results also emphasize the need to explore the modulating effects of IQ, gender and age on cognitive enhancing treatments. Noticeably, women performed significantly better than men of the same age and IQ in most cognitive tests, with the most consistent differences occurring in memory and executive functioning and negative trends rarely emerged on quality of life linked to the effect of age after adjusting for IQ and gender. In sum, the TESDAD battery is a useful neurocognitive tool for probing the clinical efficacy of experimental therapies in interventional studies in the DS population suggesting that age-matched controls are advantageous for determining normalization of DS.

Spatial-sequential and spatial-simultaneous working memory in individuals with Williams syndrome

The aim of the present study was to compare visuospatial working memory performance in 18 individuals with Williams syndrome (WS) and 18 typically developing (TD) children matched for nonverbal mental age. Two aspects were considered: task presentation format (i.e., spatial-sequential or spatial-simultaneous), and level of attentional control (i.e., passive or active tasks). Our results showed that individuals with WS performed less well than TD children in passive spatial-simultaneous tasks, but not in passive spatial-sequential tasks. The former's performance was also worse in both active tasks. These findings suggest an impairment in the spatial-simultaneous working memory of individuals with WS, together with a more generalized difficulty in tasks requiring information storage and concurrent processing, as seen in other etiologies of intellectual disability.