[Formula: see text] The role of distinct executive functions on adaptive behavior in children and adolescents with Down syndrome

Delineation of cross-domain associations between everyday executive function and adaptive behaviour in Down syndrome and Williams syndrome

In genetic syndromes such as Down syndrome (DS) and Williams syndrome (WS), difficulties with executive functioning (EF) are a commonly reported feature and a key correlate of long-term success in everyday life. Despite a robust literature in children with these syndromes, it remains unclear how cross-syndrome characteristics of everyday EF relate to adaptive functioning and intelligence among adults with DS and WS, and if these relationships differ between these groups. This study aimed to characterise the profile of strengths and weaknesses in everyday EF using the Behaviour Rating Inventory of Executive Function-Adult Informant Version (BRIEF-A) in older adolescents and young adults with DS and WS. Associations between distinct EFs, adaptive/maladaptive functioning, and intellectual ability were also investigated. Results showed that the WS group displayed profound impairments in almost all BRIEF-A scales, with a large percentage of scores in the clinically significant range. Further, selective EFs (Inhibit, Organisation of Materials, Task Monitor) were able to discriminate between the two genetic syndromes. Contrary to previous research, in WS, Working Memory was linked to adaptive functioning and IQ. In DS, the Task-Monitor and Shift scales were unique predictors of externalising and internalising behaviours, respectively. These findings could have important implications for targeted cognitive interventions in these genetic syndromes.

Laboratory-based measures of executive function and daily living skills in young children with Down syndrome: informing future interventions

BACKGROUND

Adaptive behaviour refers to the practical skills necessary for independence and is considered a high-priority intervention target for children with neurogenetic conditions associated with intellectual disability, like Down syndrome (DS). Daily living skills (DLS) are a critical aspect of adaptive behaviour, but they have received little intervention attention, possibly because they involve a wide variety of skills across many settings. The present study aimed to advance DLS intervention science by examining the concurrent and longitudinal association between DLS performances and a cognitive skillset hypothesised to support DLS skill acquisition, executive function (EF).

METHODS

Participants were 71 children with DS between the ages of 2.5 and 8.7 years (M = 5.23 years; standard deviation = 1.65) who completed a battery of adapted EF tasks and a primary caregiver who completed the Vineland Adaptive Behavior Scales 3rd Edition Parent/Caregiver Comprehensive Report Form. A subset of caregivers also provided 6- and 12-month follow-up adaptive behaviour information.

RESULTS

Results demonstrated a positive association between EF task performance and DLS standard scores and v-scores both concurrently and longitudinally.

CONCLUSIONS

The findings have implications for potential future intervention approaches that aim to strengthen DLS performances by advancing EF skills in this population.

[Formula: see text] Beyond the rubicon: a continuum approach to investigating the impact of ADHD like characteristics on everyday executive function in children with Tourette Syndrome

Across a range of neurodevelopmental conditions, a diagnosis of attention deficit hyperactivity disorder (ADHD) has been shown to be associated with executive function impairment. However, the DSM-V emphasis upon viewing psychological characteristics as existing on a continuous distributed quantitative dimension has enabled the opportunity to consider the influence of sub-diagnostic or sub-referral levels of these psychological characteristics upon cognitive function. This study adopted a continuum approach to the consideration of this ADHD influence and examined the extent to which the difference in parental reported executive functions between children with Tourette syndrome (TS) or typically developing children could be mediated by a concurrent group difference in the possession of sub-referral levels of ADHD-like characteristics. A total of 146 children, 58 with reported TS diagnosis, participated. Parental report measures of ecological executive functioning, the Child Executive Functioning Inventory, and the Vanderbilt ADHD Diagnostic Parent Rating Scale were employed. The analyses with a full sample and a sub-referral sample revealed significant group differences in most of the key measures. In addition, these measures were highly correlated even when controlling for age and gender. A series of mediation analyses indicated that in all models, the ADHD-like measures significantly mediated the group difference in executive function. These results suggest that sub-referrals levels of ADHD-like characteristics continue to contribute to executive challenges in TS. Future intervention research targeting these executive functions should consider the presence of ADHD-like characteristics at sub-referral levels of possession.

Evaluating an adapted reverse categorisation task to assess cognitive flexibility in young children with Down syndrome

BACKGROUND

Accurate measurement of cognitive skills is necessary to advance both developmental and intervention science for individuals with Down syndrome (DS). This study evaluated the feasibility, developmental sensitivity and preliminary reliability of a reverse categorisation measure designed to assess cognitive flexibility in young children with DS.

METHODS

Seventy-two children with DS ages 2.5-8 years completed an adapted version of a reverse categorisation task. Twenty-eight of the participants were assessed again 2 weeks later for retest reliability.

RESULTS

This adapted measure demonstrated adequate feasibility and developmental sensitivity, and preliminary evidence for test-retest reliability when administered to children with DS in this age range.

CONCLUSIONS

This adapted reverse categorisation measure may be useful for future developmental and treatment studies that target early foundations of cognitive flexibility in young children with DS. Additional recommendations for use of this measure are discussed.

Perspectives on adaptive functioning and intellectual functioning measures for intellectual disabilities behavioral research

Introduction

Intellectual disability (ID) is a significant limitation in both intellectual ability and adaptive functioning, but many studies of participants with ID only include a measure of overall intellectual functioning when describing their samples. The purpose of this perspective article was to provide a starting point for future research regarding the utility of including measures of both intellectual and adaptive functioning in research focused on ID. In this article, we discuss the differences and similarities between the constructs of intellectual and adaptive functioning, how they are measured, and the benefits of using both measures to describe participant abilities. Data are presented to demonstrate that intellectual and adaptive functioning measures capture separate but related skills in a sample of individuals with ID (i.e., children with Down syndrome [DS]; the leading genetic cause of ID).

Methods

Thirty children with DS (7-31 months) were administered the Mullen Scales of Early Learning and their mothers were interviewed using the Vineland Adaptive Behavior Scales.

Results

At the group level, Vineland and Mullen composite scores were relatively normally distributed and positively correlated. At the individual level, a concordance correlation coefficient indicated moderate agreement between Vineland and Mullen composite scores.

Discussion

Although many children showed consistency between measures, others did not. Our discussion and findings, though preliminary, highlight that intellectual and adaptive functioning are separate but related skills and that there are benefits to including both measures when describing samples with ID. We discuss considerations for including adaptive functioning measures to enhance future research on individuals with ID.

Cognitive flexibility assessment in youth with Down syndrome: Reliability, practice effects, and validity

BACKGROUND

Cognitive flexibility refers to the ability to switch between different mental sets, tasks, or strategies and is challenging for some individuals with Down syndrome (DS). The lack of reliable and valid cognitive flexibility measures for individuals with DS is a major barrier to clinical trials and intervention studies designed to address cognitive challenges specific to DS. To avoid measurement limitations that could confound interpretations of performance in clinical trials in children with DS, it is critical to use phenotype-sensitive and psychometrically sound measures of cognitive flexibility.

AIM

This study aimed to evaluate the psychometric properties of three measures of cognitive flexibility including Rule-Shift, Weigl Sorting, and KiTAP Flexibility in a sample of 97 youth with DS aged 6-17 years old.

METHOD

Data were collected at two time points with a two-week interval. Parents also completed adaptive behavior and cognitive flexibility questionnaires. Child cognitive and language abilities were also assessed.

RESULTS

The Weigl Sorting met the most psychometric criteria, with adequate feasibility (≥ 80 %) and significant correlations with most of the broader developmental domains; however, the levels of test-retest reliability, practice effects, and convergent validity did not meet a priori criteria. Rule-Shift and KiTAP Flexibility measures did not have acceptable feasibility; although sensitivity and specificity analyses revealed that Rule-Shift may be appropriate for a subgroup of the participants.

CONCLUSION

No evaluated measures met all psychometric study criteria and, therefore, additional evaluation of cognitive flexibility measures is needed for use among individuals with DS.

Confirmatory factor analysis of the BRIEF2 in a sample of youth with Down syndrome

BACKGROUND

The factor structure of the Behavior Rating Inventory of Executive Function, second edition (BRIEF2) has been widely examined in both typically developing children and specific clinical samples. Despite the frequent use of the BRIEF2 for measuring executive functioning in individuals with Down syndrome, no study has investigated the factorial validity or dimensionality of the BRIEF2 in this population. This study aimed to address this notable gap in the literature.

METHODS

Parents of 407 children and youth with Down syndrome aged 6-18 years completed the BRIEF2 as part of different studies led by six sites. Three competing models proposed by previous studies were analysed using Confirmatory Factor Analysis: the theoretical structure of the BRIEF2 where the scales were constrained to load on three factors labelled as Cognitive, Behavioral, and Emotional Regulation, a two-factor correlated model with the merged Behavioral and Emotional regulation, and a single-factor model.

RESULTS

The three-factor model provided a better fit than the one- and two-factor models, yet a large correlation was observed between Behavioural and Emotional regulation factors. The results provide meaningful explanatory value for the theoretical structure of the BRIEF2. However, the Behavioral and Emotional regulation factors might be less differentiated and the two-factor structure of the BRIEF2 may also make theoretical and empirical sense.

CONCLUSIONS

Although more studies are needed to further examine the factor structure of the BRIEF2 in youth with Down syndrome, this investigation provides preliminary support for the interpretation of the three executive function index scores provided by the BRIEF2: Cognitive, Behavioral, and Emotional Regulation.

The Mediatory Role of Executive Functioning on the Association Between Sleep and Both Everyday Memory and ADHD Symptoms in Children and Youth With Down Syndrome

People with Down syndrome (DS) commonly experience challenges with sleep, executive functioning, everyday memory, and symptoms of attention deficit hyperactivity disorder (ADHD). A path analysis was conducted to determine if executive function mediated the relationship between sleep problems and both everyday memory and ADHD symptoms. Parents of 96 children and youth with DS completed questionnaires related to sleep, executive functioning, everyday memory, and ADHD symptoms. Results showed that executive functioning fully mediated the relation between sleep and both everyday memory and ADHD symptoms. Implications for education and intervention for children and youth with DS are discussed.

Executive functioning and verbal fluency performance in youth with Down syndrome

BACKGROUND

Executive functioning (EF) is an area of challenge for individuals with Down syndrome (DS) associated with a variety of downstream difficulties. Verbal fluency performance is one potential downstream effect that is commonly assessed in individuals with DS due to the measure's utility as a predictor of dementia. Verbal fluency requires individuals to inhibit irrelevant responses, shift between groupings of related words, and monitor to prevent repetition, all skills related to EF.

AIMS

This study aimed to determine the association between semantic verbal fluency performance and three EF subdomains (inhibition, shifting, and working memory) in youth with DS after taking into account vocabulary and cognitive ability.

METHODS AND PROCEDURES

Neuropsychological assessments (verbal and visuospatial), and parent reports of EF, were completed at one time point by 69 youth with DS 6-17 years old and their caregivers. Expressive and receptive vocabulary skills and cognitive ability were also assessed.

OUTCOMES AND RESULTS

The results revealed that verbal fluency performance was significantly associated with neuropsychological assessments of EF and parent report of inhibition even after controlling for the effects of vocabulary and cognitive ability.

CONCLUSIONS AND IMPLICATIONS

The findings highlight the underlying importance of EF in verbal fluency tasks in youth with DS.

Profiles of Caregiver-Reported Executive Function in Children with Down Syndrome

Children with Down syndrome (DS) are at risk for challenges with aspects of executive function (EF). The current study explores whether heterogeneity in EF profiles can be detected within a sample of children with DS. Participants were 69 children with DS, ages 3-10 years (M = 6.23, SD = 1.91). T-scores from a caregiver-report measure of executive function were modeled using latent profile analysis, and auxiliary analyses examined the association between demographic and biomedical factors and probability of profile membership. The two-profile solution was the best fit for the sample, with a profile that involved elevated scores in working memory only ("Working Memory Only" profile; 43% of sample) and a "Multi-Domain" profile that involved elevated scores in planning, inhibition, and working memory (57%). The presence of congenital heart defects was associated with a higher probability of assignment to the Multi-Domain profile. Findings from this study contribute to the characterization of heterogeneous outcomes associated with DS.

Evaluating Verbal Fluency Outcome Measures in Children With Down Syndrome

This study evaluates the psychometric properties of a verbal fluency task for potential use as an outcome measure in future clinical trials involving children with Down syndrome. Eighty-five participants attempted a modified version of the Neuropsychological Assessment of Children, Second Edition Word Generation Task at two time points. In the full sample, the measure fell below a priori reliability and feasibility criteria, though feasibility of the semantic trials were higher than feasibility of the phonemic trials. Performance on the measure correlated with chronological age and IQ scores, and no sex-related effects were found. Additional analyses suggested that the semantic verbal fluency trials might be appropriate for children with Down syndrome 10 years of age and older.

Psychometric Evaluation of Social Cognition and Behavior Measures in Children and Adolescents with Down Syndrome

Individuals with Down syndrome (DS) are often described as socially engaged; however, challenges with social cognition, expressive language, and social interaction are also common in DS and are prospective outcomes of interest for clinical trials. The current study evaluates the psychometric properties of standardized measurements of social cognition and social behavior for potential use as outcome measures for children and adolescents with DS. Seventy-three youth ages 6 to 17 years old (M = 12.67, SD = 3.16) with DS were assessed on social cognition subtests of a neuropsychological assessment at two time points. Caregivers also completed a parent-report measure of social behavior. Measures were evaluated for feasibility, test-retest reliability, practice effects, convergent validity, and associations with broader developmental domains (i.e., age, cognition, and language). All social cognition and behavior measures met criteria for a portion of the psychometric indices evaluated, yet feasibility limitations were identified for the Developmental Neuropsychological Assessment, Second Edition (NEPSY-II) Affect Recognition subtest, and the NEPSY-II Theory of Mind subtest had problematic floor effects for percentile ranks. The Social Responsiveness Scale, Second Edition (SRS-2; T-scores) had high feasibility, moderate to excellent test-retest reliability, and no practice effects, suggesting this measure could be appropriate for use in clinical trials involving youth with DS.