Examining Relationships between Multiple Self-Reported Sleep Measures and Gait Domains in Cognitively Healthy Older Adults.

BACKGROUND: Gait-related changes in older adulthood may be related to changes in cognition (e.g., executive functioning), and recent work suggests that different self-reported measures of sleep may be tied to contrasting aspects of executive functioning. However, the relationship between these self-reported sleep measures and gait domains has not been explored. Such an investigation would be useful in helping to determine which older adults might exhibit changes in gait as well as experience other gait-associated changes (e.g., increased fall risk). OBJECTIVE: To examine associations between different aspects of self-reported sleep and gait domains in a sample of cognitively healthy older adults. METHOD: A total of 423 older adults (mean age 69.9 years, range 50-92) completed self-report measures of sleep quality, daytime sleepiness, and sleep-related distress. The participants also completed an objective, electronic measure of both single-task and dual-task gait (i.e., GAITRite). Principal component analyses were used to elucidate the solution for each gait condition, and multiple linear regression was used to examine the contributions of sleep measures to variability in gait performance. RESULTS: A 5-component solution of the single-task condition and a 4-component solution of the dual-task condition were identified. Multiple linear regressions revealed that a poorer sleep quality was associated with greater single-task and dual-task asymmetry. Greater daytime sleepiness was associated with increased dual-task gait variability and postural control. After controlling for the effects of other facets of sleep, sleep-related distress was not associated with any gait domain. CONCLUSIONS: Among cognitively healthy older adults,sleep quality and daytime sleepiness, but not sleep-related distress, are associated with aspects of gait. Patients who report these symptoms should be assessed and monitored for possible changes in gait.

Training, knowledge, attitudes and practices of Canadian health care providers regarding sleep and sleep disorders in children.

BACKGROUND: Sleep disorders are prevalent in children and are associated with significant comorbidity. OBJECTIVE: To assess the training, knowledge, attitudes and practices of Canadian health care providers (HCPs) regarding sleep disorders in children. METHOD: A 42-item survey, designed to collect information on frequency of paediatric sleep disorders-related screening and diagnosis, implementation of evidence-based interventions and related knowledge base, was completed by HCPs. RESULTS: Ninety-seven HCPs completed the survey. One per cent obtained training in paediatric sleep during undergraduate training and 3% obtained such training during their residencies, yet 34.9% estimated that 25 to 50% of their patients suffered from sleep disorders. Most HCPs thought that sleep disorders significantly impacted children's health and daytime function. Most HCPs screened for developmental sleep issues, but not consistently for sleep disorders. Most recommended evidence-based behavioural interventions for behavioural sleep disorders, but some also reported behavioural interventions that were not first-line or recommended. Inadequate knowledge regarding melatonin use was evident. Most participants reported rarely/never ordering a sleep study for a child with suspected obstructive sleep apnea (OSA). Most were familiar with surgical and weight loss management options for OSA; many were unfamiliar with benefits of continuous positive airway pressure. Participants' knowledge scores were highest on developmental and behavioural aspects of sleep, and lowest on sleep disorders. CONCLUSIONS: HCPs exhibit significant gaps in their knowledge, screening, evaluation and treatment practices for paediatric sleep disorders. Training at the undergraduate, graduate and postgraduate levels, as well as Continuing Medical Education are needed to optimize recognition, treatment and follow-up of paediatric sleep disorders.

Comparison of older adults' steps per day using NL-1000 pedometer and two GT3X+ accelerometer filters.

The purpose of this study was to compare the steps/d derived from the ActiGraph GT3X+ using the manufacturer's default filter (DF) and low-frequency-extension filter (LFX) with those from the NL-1000 pedometer in an older adult sample. Fifteen older adults (61-82 yr) wore a GT3X+ (24 hr/day) and an NL-1000 (waking hours) for 7 d. Day was the unit of analysis (n = 86 valid days) comparing (a) GT3X+ DF and NL-1000 steps/d and (b) GT3X+ LFX and NL-1000 steps/d. DF was highly correlated with NL-1000 (r = .80), but there was a significant mean difference (-769 steps/d). LFX and NL-1000 were highly correlated (r = .90), but there also was a significant mean difference (8,140 steps/d). Percent difference and absolute percent difference between DF and NL-1000 were -7.4% and 16.0%, respectively, and for LFX and NL-1000 both were 121.9%. Regardless of filter used, GT3X+ did not provide comparable pedometer estimates of steps/d in this older adult sample.

Childhood sleep apnea and neighborhood disadvantage.

OBJECTIVE: To determine whether neighborhood characteristics or socioeconomic status are risk factors for obstructive sleep apnea (OSA) in young children. STUDY DESIGN: In this observational study, we compared residential census tract metrics in Montreal, Canada for 436 children aged 2-8 years who were evaluated for OSA, hypothesizing that the children with proven OSA (OSA group; n = 300) would come from more disadvantaged neighborhoods compared with those children without OSA (no OSA group; n = 136). Children who had undergone previous adenotonsillectomy and those with comorbid disorders were excluded from the analysis. RESULTS: Compared with the no OSA group, the OSA group lived in census tracts with lower median family incomes, higher proportions of children living below the Canadian low-income cutoff (indicating poverty), higher proportions of single-parent families, and greater population densities. The highest probability of having OSA was seen in children referred from the most disadvantaged census tracts and was due primarily to moderate/severe OSA. Group differences remained significant when adjusted for age, race/ethnicity, and obesity. CONCLUSIONS: Compared with the children without OSA, those with OSA were more likely to reside in disadvantaged neighborhoods. Future studies should examine whether these results can be replicated in other settings, especially those with large socioeconomic disparities.

Neuroimaging, Behavioral, and Gait Correlates of Fall Profile in Older Adults.

Prior research has suggested that measurements of brain functioning and performance on dual tasks (tasks which require simultaneous performance) are promising candidate predictors of fall risk among older adults. However, no prior study has investigated whether brain function measurements during dual task performance could improve prediction of fall risks and whether the type of subtasks used in the dual task paradigm affects the strength of the association between fall characteristics and dual task performance. In this study, 31 cognitively normal, community-dwelling older adults provided a self-reported fall profile (number of falls and fear of falling), completed a gait dual task (spell a word backward while walking on a GaitRite mat), and completed a supine dual task (rhythmic finger tapping with one hand while completing the AX continuous performance task (AX-CPT) with the other hand) during functional magnetic resonance imaging (fMRI). Gait performance, AX-CPT reaction time and accuracy, finger tapping cadence, and brain functioning in finger-tapping-related and AX-CPT-related brain regions all showed declines in the dual task condition compared to the single task condition. Dual-task gait, AX-CPT and finger tapping performance, and brain functioning were all independent predictors of fall profile. No particular measurement domain stood out as being the most strongly associated measure with fall variables. Fall characteristics are determined by multiple factors; brain functioning, motor task, and cognitive task performance in challenging dual-task conditions all contribute to the risk of falling.

An anesthetic management protocol to decrease respiratory complications after adenotonsillectomy in children with severe sleep apnea.

BACKGROUND: A high incidence of respiratory morbidity after adenotonsillectomy is reported in children with obstructive sleep apnea syndrome (OSAS). In an effort to decrease this morbidity, we implemented perioperative guidelines recommending an adjustment in the administration of opioids, dexamethasone, and atropine in children with OSAS who demonstrated recurrent episodes of profound hypoxemia during the perioperative sleep study. METHODS: We performed a retrospective review and compared results with historic data from 2001. The primary outcome variable was a major respiratory medical intervention (MMI(Respiratory)). The severity of OSAS was classified with the McGill Oximetry Scoring (MOS) system, and our focus was on those children demonstrating repetitive desaturation <80% (MOS4). RESULTS: The medical records of 292 children who underwent adenotonsillectomy between October 2002 and February 2006 met the inclusion criteria and 97 had been assigned MOS4. Eleven children (11.3%) required an MMI(Respiratory). In 2001, 8 children (29.6%), assigned MOS4, required an MMI(Respiratory). Comparing the new and old guidelines, the adjusted odds ratio for MMI(Respiratory) in MOS4 was 0.30 (95% CI: 0.10-0.85). The key elements achieving this reduction in MMI(Respiratory) were dexamethasone administration and a reduced opioid dosage. In 2002 to 2006, the intraoperative opioid dose, expressed in morphine equivalents, administered to the MOS4 group was 0.10 mg . kg(-1) (0.06-0.12 mg . kg(-1)), and the postoperative morphine dose was 0.02 mg . kg(-1) (0-0.07 mg . kg(-1)). Both doses were lower than the ones administered to the concurrent comparison group, P values <0.001. CONCLUSIONS: A change in practice that included a dexamethasone administration and a reduction in opioid administration to children with profound recurrent hypoxia reduced the incidence of MMI(Respiratory) by >50%.

Predictors of Heterogeneity in Cognitive Function: APOE-e4, Sex, Education, Depression, and Vascular Risk.

OBJECTIVE: Mild cognitive impairment and dementia are clinically heterogeneous disorders influenced by diverse risk factors. Improved characterization of the effect of multiple risk factors influence on specific cognitive functions may improve understanding of mechanisms in early cognitive change and lead to more effective interventions. METHODS: Structural equation modeling (SEM) simultaneously examined the effects of modifiable (education, depression, and metabolic/vascular risk) and nonmodifiable risk factors (age, sex, and apolipoprotein E-ɛ4 allele [APOE-e4] status) on specific cognitive domains in 461 cognitively normal older adults. RESULTS: The hypothesized model(s) provided an adequate fit for the data. Sex differences in cognition, depression, and vascular risk were found. On average, men were higher in vascular risk with generally lower cognitive performance than women; women were more likely to have depression. APOE-e4 associated with depression but not age, sex, or metabolic/vascular risk. Depression associated with lower executive attention, memory, and language performance, whereas metabolic/vascular risk associated with lower executive attention, memory, and working memory. Older age and lower education are associated with worse performance across the cognitive domains. The combined risk factors accounted for 16%-47% of the variance in the cognitive domains. CONCLUSIONS: Results highlight the combined effect of risk factors on cognitive function. Future research is needed to determine whether the multifactorial risk effects on cognition vary by sex. Precision medicine approaches that integrate neuropsychological services may improve diagnostic accuracy and earlier identification of those at risk of cognitive decline.

Enhanced interleukin-8 production in mononuclear cells in severe pediatric obstructive sleep apnea.

BACKGROUND: Obstructive sleep apnea (OSA) is a risk factor for cardiovascular disease, metabolic disorders, and cognitive dysfunction. Current thinking links chronic intermittent hypoxia (CIH) with oxidative stress and systemic inflammation. However, the sequence of events leading to the morbidities associated with OSA is poorly understood in children. Monocytes are known to be altered by chronic hypoxia. Thus in this prospective study, we investigated inflammatory cytokine profiles from cultures of peripheral blood mononuclear cells (PBMC) obtained from children with severe OSA and sleep-related CIH. METHODS: Ten children with OSA (cases) and 5 age-matched children without OSA (controls) were recruited for study. Samples of plasma and PBMC were obtained before and after adenotonsillectomy. The levels of the inflammatory cytokines, interleukin (IL)-1ß, IL-6, IL-8, IL-10, IL-12p70, and tumor necrosis factor-α (TNFα), were measured in both plasma and ex vivo culture supernatants of PBMC incubated with lipopolysaccharide (LPS) using the cytometric bead assay. RESULTS: Upon activation of PBMC by LPS, the levels of IL-8 in the culture supernatants from cases were threefold higher than in controls. The levels of the other cytokines including IL-1ß, IL-6, and TNFα, in culture supernatant of PBMC from cases showed no difference from controls; nor were there significant differences in plasma cytokine levels. CONCLUSION: We speculate that in young children with sleep-related CIH, an enhanced production capacity of IL-8 precedes the development of systemic inflammatory markers. Future work should evaluate IL-8 production capacity as a potential biomarker for OSA severity.

Respiratory-swallowing interactions during sleep in premature infants at term.

Non-nutritive swallowing occurs frequently during sleep in infants and is vital for fluid clearance and airway protection. Swallowing has also been shown to be associated with prolonged apnea in some clinical populations. What is not known is whether swallowing contributes to apnea or may instead help resolve these clinically significant events. We studied the temporal relationships between swallowing, respiratory pauses and arousal in six preterm infants at term using multi-channel polysomnography and a pharyngeal pressure transducer. Results revealed that swallows occurred more frequently during respiratory pauses and arousal than during control periods. They did not trigger the respiratory pause, however, as most swallows (66%) occurred after respiratory pause onset and were often tightly linked to arousal from sleep. Swallows not associated with respiratory pauses (other than the respiratory inhibition to accommodate swallowing) and arousal occurred consistently during the expiratory phase of the breathing cycle. Results suggest that swallowing and associated arousal serve an airway protective role during sleep and medically stable preterm infants exhibit the mature pattern of respiratory-swallowing coordination by the time they reach term.

Understanding heterogeneity in older adults: Latent growth curve modeling of cognitive functioning.

BACKGROUND: Clarifying relationships between specific neurocognitive functions in cognitively intact older adults can improve our understanding of mechanisms involved in cognitive decline, which may allow identification of new opportunities for intervention and earlier detection of those at increased risk of dementia. METHOD: The present study employed latent growth curve modeling to longitudinally examine the relationship between executive attention/processing speed, episodic memory, language, and working memory functioning utilizing the neuropsychological test battery from the National Alzheimer's Disease Coordinating Center. A total of 691 relatively healthy older adults (Mage = 69.07, SD = 6.49) were assessed at baseline, and 553 individuals completed three visits spanning a two-year period. RESULTS: Better cognitive performance was concomitantly associated with better functioning across domains. Subtle declines in executive attention/processing speed processes were found, while, on average, memory and language performance improved with repeated testing. Lower executive attention/processing speed performance at baseline predicted less incremental growth rate in memory. In turn, higher initial memory functioning was associated with incremental improvements in language performance. CONCLUSIONS: These results are consistent with the notion that intact executive function and attention processes are important to preserving memory functioning with advanced age, but are also the functions most susceptible to decline with age. These findings also provide further insight into the critical role of practice effects in clinical assessment practice and have implications for pharmaceutical trials. Practice effects should be routinely considered as they may give the appearance of retention of function within the cognitive domains considered to be a hallmark of Alzheimer's disease pathology.

Adenotonsillectomy improves sleep, breathing, and quality of life but not behavior.

OBJECTIVE: To obtain parental perspectives on changes in sleep, breathing, quality of life (QOL), and neurobehavioral measures after adenotonsillectomy. STUDY DESIGN: This retrospective cohort study comprised otherwise healthy children evaluated for obstructive sleep apnea syndrome (OSAS) from 1993 to 2001. We compared those children who underwent adenotonsillectomy with those children who did not. The parents of 473 children (292 boys) 2 years of age and older were sent questionnaires to evaluate QOL and clinical and behavioral changes. For 94 children 3 years of age and older, behavioral changes were evaluated using the Conners' Parent Rating Scale-Revised (CPRS-R) for three different periods: pre-operatively/pre-polysomnography, postoperatively/postpolysomnography, and recently. RESULTS: One hundred and sixty-six questionnaires were returned (35%), 138 of which were complete with written consent provided. Compared with parents of unoperated children, parents of children who had adenotonsillectomy were more likely to report improvements in sleep, breathing, and QOL but not improvements in concentration, school performance, and intellectual or developmental progress. Both short and long term, there were no significant effects of adenotonsillectomy on any of the CPRS-R behavior subscales. CONCLUSION: From a parental perspective, adenotonsillectomy frequently improves sleep, breathing, and QOL but does not often improve neurobehavioral outcomes.

Apolipoprotein E Genotype Linked to Spatial Gait Characteristics: Predictors of Cognitive Dual Task Gait Change.

BACKGROUND: Developing measures to detect preclinical Alzheimer's Disease is vital, as prodromal stage interventions may prove more efficacious in altering the disease's trajectory. Gait changes may serve as a useful clinical heuristic that precedes cognitive decline. This study provides the first systematic investigation of gait characteristics relationship with relevant demographic, physical, genetic (Apolipoprotein E genotype), and health risk factors in non-demented older adults during a cognitive-load dual task walking condition. METHODS: The GAITRite system provided objective measurement of gait characteristics in APOE-e4 "carriers" (n = 75) and "non-carriers" (n = 224). Analyses examined stride length and step time gait characteristics during simple and dual-task (spelling five-letter words backwards) conditions in relation to demographic, physical, genetic, and health risk factors. RESULTS: Slower step time and shorter stride length associated with older age, greater health risk, and worse physical performance (ps < .05). Men and women differed in height, gait characteristics, health risk factors and global cognition (ps < .05). APOE-e4 associated with a higher likelihood of hypercholesterolemia and overall illness index scores (ps < .05). No genotype-sex interactions on gait were found. APOE-e4 was linked to shorter stride length and greater dual-task related disturbances in stride length. CONCLUSIONS: Stride length has been linked to heightened fall risk, attention decrements and structural brain changes in older adults. Our results indicate that stride length is a useful behavioral marker of cognitive change that is associated with genetic risk for AD. Sex disparities in motor decline may be a function of health risk factors.

Reliability and Validity of a Novel Internet-Based Battery to Assess Mood and Cognitive Function in the Elderly.

Dementia is a chronic condition in the elderly and depression is often a concurrent symptom. As populations continue to age, accessible and useful tools to screen for cognitive function and its associated symptoms in elderly populations are needed. The aim of this study was to test the reliability and validity of a new internet-based assessment battery for screening mood and cognitive function in an elderly population. Specifically, the Helping Hand Technology (HHT) assessments for depression (HHT-D) and global cognitive function (HHT-G) were evaluated in a sample of 57 elderly participants (22 male, 35 female) aged 59-85 years. The study sample was categorized into three groups: 1) dementia (n = 8; Mini-Mental State Exam (MMSE) score 10-24), 2) mild cognitive impairment (n = 24; MMSE score 25-28), and 3) control (n = 25; MMSE score 29-30). Test-retest reliability (Pearson correlation coefficient, r) and internal consistency reliability (Cronbach's alpha, α) of the HHT-D and HHT-G were assessed. Validity of the HHT-D and HHT-G was tested via comparison (Pearson r) to commonly used pencil-and-paper based assessments: HHT-D versus the Geriatric Depression Scale (GDS) and HHT-G versus the MMSE. Good test-retest (r = 0.80; p < 0.0001) and acceptable internal consistency reliability (α= 0.73) of the HHT-D were established. Moderate support for the validity of the HHT-D was obtained (r = 0.60 between the HHT-D and GDS; p < 0.0001). Results indicated good test-retest (r = 0.87; p < 0.0001) and acceptable internal consistency reliability (α= 0.70) of the HHT-G. Validity of the HHT-G was supported (r = 0.71 between the HHT-G and MMSE; p < 0.0001). In summary, the HHT-D and HHT-G were found to be reliable and valid computerized assessments to screen for depression and cognitive status, respectively, in an elderly sample.

Longitudinal assessment of neuropsychological and temporal/spatial gait characteristics of elderly fallers: taking it all in stride.

Gait abnormalities are linked to cognitive decline and an increased fall risk within older adults. The present study addressed gaps from cross-sectional studies in the literature by longitudinally examining the interplay between temporal and spatial aspects of gait, cognitive function, age, and lower-extremity strength in elderly "fallers" and "non-fallers". Gait characteristics, neuropsychological and physical test performance were examined at two time points spaced a year apart in cognitively intact individuals aged 60 and older (N = 416). Mixed-model repeated-measure ANCOVAs examined temporal (step time) and spatial (stride length) gait characteristics during a simple and cognitive-load walking task in fallers as compared to non-fallers. Fallers consistently demonstrated significant alterations in spatial, but not temporal, aspects of gait as compared to non-fallers during both walking tasks. Step time became slower as stride length shortened amongst all participants during the dual task. Shorter strides and slower step times during the dual task were both predicted by worse executive attention/processing speed performance. In summary, divided attention significantly impacts spatial aspects of gait in "fallers", suggesting stride length changes may precede declines in other neuropsychological and gait characteristics, thereby selectively increasing fall risk. Our results indicate that multimodal intervention approaches that integrate physical and cognitive remediation strategies may increase the effectiveness of fall risk interventions.

Scoring arousals in the home environment.

Arousals from sleep and consequent sleep disruption may be a causal link between sleep-disordered breathing and its sequellae in children. Quantification of arousals therefore makes an important contribution to the overall assessment of the sleep of a child with suspected obstructive sleep apnea (OSA) or other sleep disorders. Arousals are classically defined by changes in the electroencephalographic (EEG) channels, but most arousals in children involve body movement in addition to EEG changes. Several methods of quantifying arousals without the use of EEG have been proposed, with the aim of simplifying testing in children with suspected OSA so that it can be safely and efficiently performed in the child's home. The following paper gives a background to the assessment of arousals from sleep in children, and describes methods for detecting arousals and their potential application to recordings performed in a child's home.

Sleep and breathing in Prader-Willi syndrome.

Prader-Willi syndrome (PWS) is a genetic disorder, with hypotonia being the predominant feature in infancy, and developmental delay, obesity, and behavioral problems becoming more prominent in childhood and adolescence. Children with this disorder frequently suffer from excessive daytime sleepiness and have a primary abnormality of the circadian rhythm of rapid eye movement sleep. They also have primary abnormal ventilatory responses to hypoxia and hypercapnia, and these abnormalities may be exacerbated by obesity. Children with PWS are at risk of a variety of abnormalities of breathing during sleep, including obstructive sleep apnea and sleep-related alveolar hypoventilation. Clinical evaluation should include a careful history of sleep-related symptoms and assessment of the upper airway and lung function. Polysomnography should be considered for those with symptoms suggestive of sleep-disordered breathing. Treatment options depend on the underlying problem, but may include behavioral interventions, weight control, adenotonsillectomy, and nocturnal ventilation.