Characterization of a sleep architectural phenotype in children with Down syndrome.

PURPOSE: Evidence suggests that while the high prevalence of obstructive sleep apnea (OSA) in children with Down syndrome (DS) likely contributes to sleep fragmentation, their poor sleep is only partly attributable to the presence of OSA. We hypothesized that a sleep phenotype exists for DS, which would be independent of OSA and evident across childhood. METHODS: This is a retrospective study of sleep architecture in children with DS together with matched controls. All subjects underwent baseline polysomnography between January 1985 and January 2013. Case-control pairs were compared according to age group. RESULTS: Sleep characteristics were compared in 130 DS subjects aged 0-17.8 years (median 5.8 years) and 130 matched controls. Body mass index z-scores were similar between cases and controls. Compared to controls, children with DS had a lower sleep efficiency and higher percentage of slow-wave sleep at 2-6.9, 7-11.9, and 12-17.9 years (p <0.05 for all) as well as reduced rapid-eye movement (REM) sleep percentage, significant at 7-11.9 years (p <0.05). Children with DS exhibited increased N1 sleep at 2-6.9 years but decreased N1 sleep at 12-17.9 years compared to controls (p <0.05 for both). CONCLUSIONS: Children with DS exhibit altered sleep architecture when compared to non-DS children of similar age and OSA severity. Notably, reduced REM sleep and increased slow-wave sleep was seen independent of OSA in children with DS over 2 years. Amounts of both REM and non-REM sleep may have important implications for learning, memory, and behavior, all the more significant in this population with baseline neurocognitive impairment.

Effect of body position and sleep state on obstructive sleep apnea severity in children with Down syndrome.

STUDY OBJECTIVES: To investigate the influence of sleep position and sleep state on obstructive sleep apnea (OSA) severity in in children with Down syndrome (DS). DESIGN: Retrospective review. SETTING: Sleep disorders laboratory of a tertiary medical center. PARTICIPANTS: Children with Down syndrome and typically developing children matched for age, gender, apneahypopnea index (AHI), and year of polysomnogram. MEASUREMENTS AND RESULTS: Sleep variables from baseline polysomnography. Sensor-recorded position (supine, prone, lateral) was expressed as the percentage of total sleep time. The AHI was calculated in each sleep state (NREM, REM), position, and position-sleep state combination. Of 76 DS subjects (55% male) the median age and AHI were 4.6 years (range 0.2-17.8 years) and 7.4 events/h (range 0-133). In all subjects, AHI was higher in REM than NREM (p < 0.05); however, the NREM AHI was higher in DS subjects than controls (p < 0.05). Compared to controls, the percentage of prone sleep was greater in DS subjects (p < 0.05), but the percentage of supine or non-supine (prone plus lateral) sleep was no different. For DS subjects alone, NREM AHI was higher in supine than non-supine sleep (p < 0.05). CONCLUSION: In DS and non-DS children alike, respiratory events are predominantly REM related. However, when matched for OSA severity, children with DS have a higher NREM AHI, which is worse in the supine position, perhaps indicating a positional effect compounded by underlying hypotonia inherent to DS. These findings illustrate the clinical importance of NREM respiratory events in the DS population and implications for treatment options.

Effect of propranolol on naming in chronic Broca's aphasia with anomia.

Previous research suggests that the noradrenergic system modulates flexibility of access to the lexical-semantic network, with propranolol benefiting normal subjects in lexical-semantic problem solving tasks. Patients with Broca's aphasia with anomia have impaired ability to access appropriate verbal output for a given visual stimulus in a naming task. Therefore, we tested naming in a pilot study of chronic Broca's aphasia patients with anomia after propranolol and after placebo in a double-blinded crossover manner. Naming was better after propranolol than after placebo, suggesting a potential benefit from propranolol in chronic Broca's aphasia with anomia. Larger follow-up studies are necessary to further investigate this effect.