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.

Acquisition of cognitive and communication milestones in infants with Down syndrome.

BACKGROUND: Understanding the timing of developmental milestones in typical and clinical populations facilitates intervention planning and the early detection of risk for co-occurring conditions. Normative timing of developmental milestone achievement has been established for typically developing children. However, there is little information regarding the timing of cognitive and communication skill acquisition in young children with Down syndrome (DS). The objectives of this study are to (1) provide foundational information regarding the timing of cognitive and communication skill acquisition in infants with DS and (2) facilitate the early identification of infants with risk for co-occurring conditions. METHOD: Seventy-four infants with DS (age range: 4-18 months) completed the Bayley Scales of Infant Development-III (Bayley 2006). Individual items from the cognitive and communication scales were selected for analysis. Parents provided information regarding their infant's developmental and family history. RESULTS: The percentage of infants who attained each skill was calculated within 2-month age bands. For infants who did not show skill acquisition within each age band, the rates of prematurity, heart defects, corrective heart surgery and significant illness were calculated as well. CONCLUSIONS: This study provides foundational information that can contribute to the formulation of a developmental schedule for cognitive and language milestone acquisition in infants with DS.

Early developmental profiles among infants with Down syndrome.

BACKGROUND: Down syndrome (DS) generally predisposes children to a pattern of relative developmental strengths and challenges, but within-syndrome heterogeneity is also commonly observed across many dimensions. The present research examines whether heterogeneity in developmental presentation can be detected during infancy in DS and whether factors associated with differing profiles can be identified. METHODS: Infants with DS (n = 75; age range: 3.9-17.6 months) were administered the Bayley Scales of Infant Development III (Bayley-III). A primary caregiver provided information regarding developmental history and family demographics. Latent profile analysis was conducted to identify whether early profiles were present across the five Bayley-III domains. RESULTS: Three developmental profiles were observable within the sample: a 'Mild Delay' Profile, an 'Moderate Delay' Profile and a 'Pronounced Delay' Profile. In addition, chronological age, having received heart surgery and having received occupational therapy were associated with probability of profile membership. CONCLUSIONS: Findings from this study contribute to the growing knowledgebase regarding heterogenous presentations associated with DS and can inform early intervention planning.

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.

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.

Latent profiles of autism symptoms in children and adolescents with Down syndrome.

BACKGROUND: Down syndrome (DS) is associated with elevated rates of autism spectrum disorder (ASD) and autism symptomatology. To better characterise heterogeneity in ASD symptomatology in DS, profiles of caregiver-reported ASD symptoms were modelled for children and adolescents with DS. METHODS: Participants (n = 125) were recruited through several multi-site research studies on cognition and language in DS. Using the Social Responsiveness Scale-2 (SRS-2; Constantino and Gruber 2012), two latent profile analyses (LPA) were performed, one on the broad composite scores of social communication and interaction and restricted interests and repetitive behaviour, and a second on the four social dimensions of social communication, social motivation, social awareness, and social cognition. RESULTS: A three-profile model was the best fit for both analyses, with each analysis yielding a low ASD symptom profile, an elevated or mixed ASD symptom profile and a high ASD symptom profile. Associations were observed between profile probability scores and IQ, the number of co-occurring biomedical conditions reported, sex, and SRS-2 form. CONCLUSIONS: Characterising heterogeneity in ASD symptom profiles can inform more personalised supports in this population, and implications for potential therapeutic approaches for individuals with DS are discussed.

Feasibility of a syndrome-informed micro-intervention for infants with Down syndrome.

BACKGROUND: Infants with Down syndrome (DS) are at risk for a range of phenotypic outcomes, including delays in the onset of reaching behaviour, a critical skill that facilitates early learning. This parallel-group feasibility and pilot study presents findings from a parent-mediated micro-intervention that aimed to support the development of reaching behaviour in a sample of infants with DS. METHODS: Participants were 73 infants with DS and their caregivers. Infants who qualified for the home-based intervention (based on manual skill performance on Bayley Scales of Infant and Toddler Development, Third Edition items) were randomly assigned individually or by geographical region to a treatment or an alternative treatment condition that involved toy-based interactions with caregivers. Infants in the treatment condition experienced facilitated reaching during the toy-based interactions through the use of Velcro-affixed mittens and toys. RESULTS: Forty-two infants met criteria to participate in the intervention, and 37 participated in both baseline and post-treatment visits. At post-treatment, infants in the treatment condition demonstrated shorter latencies to make contact with objects and showed higher frequencies of reach attempts and swats at objects than infants in the alternative treatment group. These findings were more pronounced when examining a chronological age-restricted subgroup of infants 5 to 10 months. CONCLUSIONS: Findings suggest that a syndrome-informed approach to targeted intervention may be a promising application of phenotyping science in DS and other neurogenetic conditions associated with intellectual disability.

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.

Parenting behaviour and executive function in children with Down syndrome.

BACKGROUND: Parenting behaviours influence many domains of child development, and recent work has demonstrated the specific effects of parenting on the development of executive function (EF) abilities. The relationship between parent-child interaction patterns and EF has been examined in typically developing (TD) children but has not yet been examined in dyads where the child has a diagnosis of Down syndrome (DS). METHOD: The current study examines the differences in patterns of parenting behaviours between DS dyads and dyads with TD children equated on nonverbal mental age. DS dyads (n = 42), child ages 59 to 118 months, and TD dyads (n = 28), child ages 30 to 49 months, participated in a modified version of the Parent-Child Challenge Task. Parent directive and teaching behaviours were coded, along with child compliance and noncompliance. Child participants also completed a laboratory measure of inhibition and working memory, and parents completed the Behaviour Rating Inventory of Executive Function-Preschool. RESULTS: There was a greater frequency of parenting directives and child compliance in the DS dyads, and parents of children with DS were more likely to follow child compliance with directives than parents of TD children. In both groups, parenting directive behaviour was a significant predictor of child EF laboratory performance. CONCLUSIONS: Results characterise the relationship between specific parenting behaviours and child EF in DS and TD dyads. The implications for parent training and intervention are discussed.

Correlates of early cognition in infants with Down syndrome.

BACKGROUND: While delays in cognitive development are detectable during early development in Down syndrome, the neuropsychological and biomedical underpinnings of cognitive skill acquisition in this population remain poorly understood. METHOD: To explore this issue, 38 infants with Down syndrome [mean chronological age = 9.65 months; SD = 3.64] completed the Bayley Scales of Infant Development-III and a set of laboratory tasks that measured sustained attention (duration of visual attention during a 1-min object exploration task), attention shifting (mean latency to shift attention on an alternating object presentation task) and visual short-term memory (dishabituation to a novel object on a change preference task). RESULTS: Latency to shift attention was negatively associated with Bayley Cognitive Scale raw scores, even when controlling for the effects of chronological age, r (33) = -.41, P = .02. In addition, prematurity status was associated with latency to shift attention. CONCLUSIONS: Early attention shifting may be an important factor that facilitates overall cognitive skill acquisition in infants with Down syndrome, and premature birth may be a risk factor for difficulties on this dimension.

Sensory processing in the postinstitutionalized child.

OBJECTIVE: The purpose of this study was to examine whether children adopted from Romanian orphanages have difficulty with sensory processing and related behaviors. METHOD: Seventy-three children adopted from Romanian orphanages were compared with 72 peers who were typically developing. The subjects' ages ranged from 3 to 6 years. The parent-report Developmental and Sensory Processing Questionnaire was used to assess sensory processing and related behaviors. The tool consists of questions in six sensory processing domains and five related behavioral domains. RESULTS: Multiple t tests indicated that the subjects adopted from Romanian orphanages demonstrated significantly greater problems than those in the control group on five of the six sensory processing domains: touch, movement-avoids, movement-seeks, vision, and audition. Additionally, the Romanian subjects exhibited significantly greater problems than the control subjects on four of the five behavioral domains: activity level, feeding, organization, and social-emotional. CONCLUSIONS: These findings substantiate clinical observations and parent reports of sensory processing deficits in children adopted from Romanian orphanages and highlight the critical importance of the environment for sensory integration. The findings also enhance our understanding of how children who were previously institutionalized respond to the human and physical environment.