Youth with Down syndrome display widespread increased functional connectivity during rest.

Studies of resting-state functional connectivity in young people with Down syndrome (DS) have yielded conflicting results. Some studies have found increased connectivity while others have found a mix of increased and decreased connectivity. No studies have examined whole-brain connectivity at the voxel level in youth with DS during an eyes-open resting-state design. Additionally, no studies have examined the relationship between connectivity and network selectivity in youth with DS. Thus, the current study sought to fill this gap in the literature. Nineteen youth with DS (Mage = 16.5; range 7-23; 13 F) and 33 typically developing (TD) youth (Mage = 17.5; range 6-24; 18 F), matched on age and sex, completed a 5.25-min eyes-open resting-state fMRI scan. Whole-brain functional connectivity (average Pearson correlation of each voxel with every other voxel) was calculated for each individual and compared between groups. Network selectivity was then calculated and correlated with functional connectivity for the DS group. Results revealed that whole-brain functional connectivity was significantly higher in youth with DS compared to TD controls in widespread regions throughout the brain. Additionally, participants with DS had significantly reduced network selectivity compared to TD peers, and selectivity was significantly related to connectivity in all participants. Exploratory behavioral analyses revealed that regions showing increased connectivity in DS predicted Verbal IQ, suggesting differences in connectivity may be related to verbal abilities. These results indicate that network organization is disrupted in youth with DS such that disparate networks are overly connected and less selective, suggesting a potential target for clinical interventions.

Sensory Processing and Maladaptive Behavior: Profiles Within the Down Syndrome Phenotype.

Aim: Sensory processing impairments are well characterized in children with neurodevelopmental disorders, particularly autism, and have been associated with maladaptive behaviors. However, little is known regarding sensory processing difficulties within Down syndrome, or how these difficulties may influence maladaptive behavior. This study aims to characterize sensory processing difficulties within the Down syndrome phenotype and determine the influence of processing difficulties on maladaptive behavior. Methods: To explore this issue, we administered the Short Sensory Profile and the Developmental Behavior Checklist to parents or primary caregivers of young children with DS (N = 49; M nonverbal mental age (NVMA) = 30.92 months (SD = 12.30); M chronological age (CA) = 67.04 (SD = 25.13). Results: Results indicated that Low Energy/Weak, Under-responsive/Seeks Sensation, and Auditory Filtering were the areas of greatest sensory regulation difficulty, and that Self-Absorbed behavior and Disruptive/Antisocial behavior were elevated areas of maladaptive behavior. Multivariate regression analyses indicated that Under-responsive/Seeks Sensation was the only sensory regulation domain significantly associated with Self-Absorbed and Disruptive/Antisocial behavior. Conclusion: Findings indicate a consistent pattern of sensory processing impairments and associations with maladaptive behavior in children with DS. Implications for interventions are discussed.

Autism spectrum disorder (ASD) symptom profiles of children with comorbid Down syndrome (DS) and ASD: A comparison with children with DS-only and ASD-only.

BACKGROUND: Down syndrome (DS) is associated with increased rates of autism spectrum disorder (ASD), characterized by social-communicative impairments (SOC-COM) and repetitive behaviors and interests (RBI). However, little is known about the ASD symptom presentation in children with DS + ASD. AIMS: The current study sought to describe parent-report of SOC-COM and RBI symptoms on the Autism Diagnostic Interview -Revised (ADI-R) in children with DS (n = 22), DS + ASD (n = 11), and ASD (n = 66). METHOD: SOC-COM and RBI scores from the ADI-R were compared across the groups whose autism status was ascertained using the Autism Diagnostic Observation Schedule. RESULTS: Differences in SOC-COM and RBI symptom severity was observed. The general pattern of findings was ASD > DS+ASD > DS. Dissimilar ASD symptom profiles were observed across groups. In ASD, SOC-COM scores were higher than RBI scores; in DS + ASD, similar SOC-COM and RBI scores were observed. Lastly, SOC-COM impairments were highly related to verbal cognition in youth with DS + ASD but not in those with DS or ASD. CONCLUSIONS AND IMPLICATIONS: These findings suggest that children with DS + ASD have a distinct profile of ASD symptoms that differs from peers with either disorder in isolation. Thus, care should be taken in evaluating and designing treatments for this group.

Verbal short-term memory deficits in Down syndrome: phonological, semantic, or both?

The current study examined the phonological and semantic contributions to the verbal short-term memory (VSTM) deficit in Down syndrome (DS) by experimentally manipulating the phonological and semantic demands of VSTM tasks. The performance of 18 individuals with DS (ages 11-25) and 18 typically developing children (ages 3-10) matched pairwise on receptive vocabulary and gender was compared on four VSTM tasks, two tapping phonological VSTM (phonological similarity, nonword discrimination) and two tapping semantic VSTM (semantic category, semantic proactive interference). Group by condition interactions were found on the two phonological VSTM tasks (suggesting less sensitivity to the phonological qualities of words in DS), but not on the two semantic VSTM tasks. These findings suggest that a phonological weakness contributes to the VSTM deficit in DS. These results are discussed in relation to the DS neuropsychological and neuroanatomical phenotype.