ACTBArizona Cognitive Test Battery AHI Apnea-hypopnea index IED Intra-extra dimensional set shift OSAS Obstructive sleep apnea syndrome PSG PolysomnographyAIM Good-quality sleep is essential for normal learning and memory. Sleep fragmentation and disrupted sleep architecture are commonly observed throughout the lifespan of individuals with Down syndrome, a condition marked by cognitive deficits emerging within the first few months of life. While obstructive sleep apnea syndrome (OSAS) is known to contribute to the loss of sleep quality in Down syndrome, its relation to cognitive and behavioral impairment remains poorly understood.METHOD Using ambulatory polysomnography, we measured sleep in an unreferred community-based sample of 38 individuals with Down syndrome (15 males, 23 females; mean age 9y 7mo (SD 1y 9mo), range 7-12y). Cognitive outcomes were assessed with the Arizona Cognitive Test Battery, a set of psychometric measures designed and validated for this population.RESULTS Among children with Down syndrome, mean Verbal IQ score (p=0.006) was 9 points lower in those with comorbid OSAS (apnea-hypopnea index >1.5) than in those without OSAS, and performance on measures of cognitive flexibility was poorer (p=0.03). In addition, those with OSAS showed increased light-stage sleep (p=0.009) at the expense of slow-wave sleep (p=0.04).INTERPRETATION These findings demonstrate a relation between OSAS and cognitive outcomes in Down syndrome. More work is required to fully understand the mechanisms underlying the links between poor sleep and impaired cognitive function. Overall, these findings highlight the importance of adequate sleep in typically and atypically developing populations.Down syndrome (trisomy 21) is the most common genetically defined cause of intellectual disability, with over 300 000 affected individuals residing in the United States alone. 1 The condition is characterized by decline of IQ during the infant and toddler years, well-documented deficits in the assimilation and expressive use of language, and impairments in cognitive flexibility and memory.2 As a result of alterations in craniofacial and oral musculature development and low muscle tone, individuals with Down syndrome are exceptionally vulnerable to obstructive sleep apnea syndrome (OSAS) from infancy, with estimates of the prevalence of the condition ranging from 30% to as high as 80%. [3][4][5] Ashworth et al. 6 have recently described the extent of sleep disruption in individuals with Down syndrome, noting that such individuals displayed more fragmented sleep than those with Williams syndrome, another intellectual disability. Because of the extent of their sleep disruption, individuals with Down syndrome could potentially suffer ill effects during critical periods of cognitive development.OSAS occurs when the upper airway becomes intermittently obstructed during sleep, resulting in incomplete ventilation, blood gas irregularities, and sleep fragmentation. It is best diagnosed with polysomnography (PSG), the criterion standard for sle...

Results showed that individuals with DS are poorer than controls in the spatial-simultaneous tasks, but not in the spatial-sequential tasks. These findings were not due to a difference in speed of visuospatial processing. In fact, when performances of the two groups in VSWM were compared using speed measures as covariates, differences between groups remained. It is suggested that the simultaneous VSWM deficit of individuals with DS could be due to the request for processing more than one item at a time.

Recent evidence has suggested that sleep may facilitate language learning. The current study examined variation in language ability in 29 toddlers with Down syndrome (DS) in relation to levels of sleep disruption. Toddlers with DS and poor sleep (66%, n = 19) showed greater deficits on parent-reported and objective measures of language, including vocabulary and syntax. Correlations between sleep and language were found in groups with equivalent medical and social backgrounds and after control for relevant behavioral co-morbidities, including autism symptoms. These results emphasize the important role of quality sleep in all children’s expressive language development, and may help increase our understanding of the etiology of language deficits in developmental disorders, potentially leading to new treatment approaches.

No abstract

Spatial context supports memory retrieval in adults. To understand the development of these effects, context effects on object recognition were tested in neurotypical children ages 3 years to adulthood (n 3–6 years = 34, n 10–16 years = 32, n college age = 22) and individuals with Down syndrome (DS) ages 10–29 years (n = 21). Participants engaged in an object recognition task; objects were presented in scenes and either remained in that same scene or were removed at test. In some groups (<4.5 years and with DS) context effects were present even though object recognition was poor. After 4.5 years, children demonstrated memory flexibility, while later in adolescence context effects reemerged, showing nonlinearity in the development of these effects.