Association between slow-wave activity, cognition and behaviour in children with sleep-disordered breathing

Neurobehavioral Associations with NREM and REM Sleep Architecture in Children with Autism Spectrum Disorder

Objective: Insomnia and daytime behavioral problems are common issues in pediatric autism spectrum disorder (ASD), yet specific underlying relationships with NonRapid Eye Movement sleep (NREM) and Rapid Eye Movement (REM) sleep architecture are understudied. We hypothesize that REM sleep alterations (REM%, REM EEG power) are associated with more internalizing behaviors and NREM sleep deficits (N3%; slow wave activity (SWA) 0.5–3 Hz EEG power) are associated with increased externalizing behaviors in children with ASD vs. typical developing controls (TD). Methods: In an age- and gender-matched pediatric cohort of n = 23 ASD and n = 20 TD participants, we collected macro/micro sleep architecture with overnight home polysomnogram and daytime behavior scores with Child Behavior Checklist (CBCL) scores. Results: Controlling for non-verbal IQ and medication use, ASD and TD children have similar REM and NREM sleep architecture. Only ASD children show positive relationships between REM%, REM theta power and REM beta power with internalizing scores. Only TD participants showed an inverse relationship between NREM SWA and externalizing scores. Conclusion: REM sleep measures reflect concerning internalizing behaviours in ASD and could serve as a biomarker for mood disorders in this population. While improving deep sleep may help externalizing behaviours in TD, we do not find evidence of this relationship in ASD.

Slow EEG Oscillation to Characterize Pediatric Sleep Apnea and Associated Cognitive Impairments

Previous studies have suggested that the typical slow oscillations (SO) characteristics during sleep could be modified in the presence of pediatric obstructive sleep apnea (OSA). Here, we evaluate whether these modifications are significant and if they may reflect cognitive deficits. We recorded the overnight electroencephalogram (EEG) of 294 pediatric subjects (5-9 years old) using eight channels. Then, we divided the cohort in three OSA severity groups (no OSA, mild, and moderate/severe) to characterize the corresponding SO using the spectral maximum in the slow wave sleep (SWS) band δ₁: 0.1-2 Hz (Maxs o), as well as the frequency where this maximum is located (FreqMaxso). Spectral entropy (SpecEn) from δ₁ was also included in the analyses. A correlation analysis was performed to evaluate associations of these spectral measures with six OSA-related clinical variables and six cognitive scores. Our results indicate that Maxso could be used as a moderate/severe OSA biomarker while providing useful information regarding verbal and visuo-spatial impairments, and that FreqMaxso emerges as an even more robust indicator of visuospatial function. In addition, we uncovered novel insights regarding the ability of SpecEn in δ₁ to characterize OSA-related disruption of sleep homeostasis. Our findings suggest that the information from SO may be useful to automatically characterize moderate/severe pediatric OSA and its cognitive consequences. Clinical Relevance- This study contributes towards reaching an objective quantifiable and automated assessment of the potential cognitive consequences of pediatric sleep apnea.

Covering the Gap Between Sleep and Cognition – Mechanisms and Clinical Examples

A growing number of studies have shown the strong relationship between sleep and different cognitive processes, especially those that involve memory consolidation. Traditionally, these processes were attributed to mechanisms related to the macroarchitecture of sleep, as sleep cycles or the duration of specific stages, such as the REM stage. More recently, the relationship between different cognitive traits and specific waves (sleep spindles or slow oscillations) has been studied. We here present the most important physiological processes induced by sleep, with particular focus on brain electrophysiology. In addition, recent and classical literature were reviewed to cover the gap between sleep and cognition, while illustrating this relationship by means of clinical examples. Finally, we propose that future studies may focus not only on analyzing specific waves, but also on the relationship between their characteristics as potential biomarkers for multiple diseases.

Pediatric Sleep Apnea: The Overnight Electroencephalogram as a Phenotypic Biomarker

Pediatric obstructive sleep apnea (OSA) is a prevalent disorder that disrupts sleep and is associated with neurocognitive and behavioral negative consequences, potentially hampering the development of children for years. However, its relationships with sleep electroencephalogram (EEG) have been scarcely investigated. Here, our main objective was to characterize the overnight EEG of OSA-affected children and its putative relationships with polysomnographic measures and cognitive functions. A two-step analysis involving 294 children (176 controls, 57% males, age range: 5-9 years) was conducted for this purpose. First, the activity and irregularity of overnight EEG spectrum were characterized in the typical frequency bands by means of relative spectral power and spectral entropy, respectively: δ1 (0.1-2 Hz), δ2 (2-4 Hz), θ (4-8 Hz), α (8-13 Hz), σ (10-16 Hz), β1 (13-19 Hz), β2 (19-30 Hz), and γ (30-70 Hz). Then, a correlation network analysis was conducted to evaluate relationships between them, six polysomnography variables (apnea-hypopnea index, respiratory arousal index, spontaneous arousal index, overnight minimum blood oxygen saturation, wake time after sleep onset, and sleep efficiency), and six cognitive scores (differential ability scales, Peabody picture vocabulary test, expressive vocabulary test, design copying, phonological processing, and tower test). We found that as the severity of the disease increases, OSA broadly affects sleep EEG to the point that the information from the different frequency bands becomes more similar, regardless of activity or irregularity. EEG activity and irregularity information from the most severely affected children were significantly associated with polysomnographic variables, which were coherent with both micro and macro sleep disruptions. We hypothesize that the EEG changes caused by OSA could be related to the occurrence of respiratory-related arousals, as well as thalamic inhibition in the slow oscillation generation due to increases in arousal levels aimed at recovery from respiratory events. Furthermore, relationships between sleep EEG and cognitive scores emerged regarding language, visual-spatial processing, and executive function with pronounced associations found with EEG irregularity in δ1 (Peabody picture vocabulary test and expressive vocabulary test maximum absolute correlations 0.61 and 0.54) and β2 (phonological processing, 0.74; design copying, 0.65; and Tow 0.52). Our results show that overnight EEG informs both sleep alterations and cognitive effects of pediatric OSA. Moreover, EEG irregularity provides new information that complements and expands the classic EEG activity analysis. These findings lay the foundation for the use of sleep EEG to assess cognitive changes in pediatric OSA.

Associations Between Sleep-Disordered Breathing and Behavioral and Cognitive Functions in Children With and Without Attention-Deficit/Hyperactivity Disorder

BACKGROUND

Sleep-related problems are highly prevalent comorbidities in Attention-Deficit/Hyperactivity Disorder (ADHD).

OBJECTIVE

This study aimed to investigate the associations between sleep-disordered breathing (SDB) and behavioral and cognitive functions in children with and without ADHD.

METHODS

A total of 341 children were included (ADHD group: 155, control group: 186; age: 6-10 years). The participants' sleep-related symptoms were assessed using a parent-rated questionnaire, and they were categorized into low- and high-risk SDB groups based on their scores. Behavioral symptoms were assessed using the Behavioral Assessment System for Children, Second Edition (BASC-2), and cognitive sustained attention and inhibitory control were assessed using a computer-based continuous performance test.

RESULTS

In the ADHD group, the high-risk SDB children showed significantly higher scores than the low-risk SDB group in externalizing problems (F = 4.22; P = 0.042), including hyperactivity (F = 4.65; P = 0.033) and attention problems (F = 8.19; P = 0.005), but not internalizing problems. Meanwhile, in the control group, the high-risk SDB children showed significantly higher scores than the low-risk SDB group in internalizing problems (F = 9.89; P = 0.002), depression (F = 9.45; P = 0.002), and somatization (F = 7.83; P = 0.006), as well as in externalizing problems (F = 7.72; P = 0.006), including hyperactivity (F = 6.23; P = 0.013), aggression (F = 5.00; P = 0.027), and conduct problems (F = 6.79; P = 0.010). Contrary to the behavioral outcomes, none of the attention performance subscale scores showed significant differences between the high- and low-risk SDB groups in either the ADHD or control group.

CONCLUSIONS

The present findings suggest that SDB is associated with behavioral problems in children with ADHD and controls, with stronger associations in control children. On the contrary, SDB has no association with cognitive attention performance. This study extends our understanding of the associations of SDB with behavioral symptoms and cognitive functions in children.

Adenotonsillectomy for paediatric sleep disordered breathing in Australia and New Zealand

AIMS

To review the contributions of Australian and New Zealand research on adenotonsillectomy for the treatment of symptoms of obstructed breathing during sleep (sleep disordered breathing, SDB) in children.

METHODS

A search of the scientific literature was conducted using the MEDLINE (Ovid), PubMed and Scopus databases in August 2020. The following search string was used: (tonsillectomy OR adenoidectomy OR adenotonsillectomy) AND (paediatric OR child) AND (Australia OR New Zealand). A focused internet search was additionally conducted on Google to identify grey literature.

RESULTS

Researchers from Australia and New Zealand have made important contributions to the understanding and improvement of adenotonsillectomy (AT), including its epidemiology, cost, surgical techniques and peri-operative safety. Rates of AT have fluctuated over the years, becoming the most common paediatric surgery today, with SDB becoming the most common indication. Research in Australia and New Zealand has also focussed on the impact of AT on quality of life, and behaviour, neurocognition and cardiovascular sequelae.

CONCLUSIONS

Australian and New Zealand researchers have played a significant role in understanding the epidemiology and improving the safety of AT. There are promising directions in research still to come, including better understanding of the reasons for geographical variation in surgery rates, developing more efficient pre-operative risk assessment tools and alternative treatment options for mild OSA.

Consequences of paediatric sleep disordered breathing: contributions from Australian and New Zealand investigators

AIMS

To highlight the contributions of Australian and New Zealand researchers to the identification of the consequences of paediatric sleep disordered breathing (SDB).

METHODS

A search was conducted in PubMed using the terms "sleep disordered breathing" "child" and "Australia or New Zealand". All abstracts were reviewed and those which focused on the consequences of SDB have been included.

RESULTS

Australasian research into the consequences of SDB has grown exponentially over the last 35 years. SDB has significant adverse consequences for quality of life, behaviour, neurocognition and the cardiovascular system and the Australasian research studies investigating these are summarised.

CONCLUSIONS

Australian and New Zealand researchers have played a significant role in understanding the consequences of paediatric SDB and the mechanisms which underpin these. The research conducted "Downunder" has led the world in this field of research and will continue to provide evidence to improve the lives of children not only in Australasia but around the world.

Associations among High Risk for Sleep-disordered Breathing, Related Risk Factors, and Attention Deficit/Hyperactivity Symptoms in Elementary School Children

Objective

: Habitual snoring is a common problem in children. We evaluated the association between a high risk for sleep-disordered breathing and attention deficit/hyperactivity symptoms.

Methods

Parents of 13,560 children aged 6 to 12 years responded to questionnaires including items on habitual snoring and the Korean attention deficit/hyperactivity disorder rating scale. The snoring score comprised the number of "yes" responses to habitual-snoring items, and a high risk for sleep-disordered breathing was defined as a snoring score ≥ 2.

Results

The odds ratio (OR) of a high risk for sleep-disordered breathing was significantly higher in boys (OR = 1.47; p < 0.001), overweight children (OR = 2.20; p < 0.001), and children with current secondhand-smoking exposure (OR = 1.38; p < 0.001). The Korean attention deficit/hyperactivity disorder rating scale score increased significantly with the snoring score (0 vs. 1, B = 1.56, p < 0.001; 0 vs. 2, B = 2.44, p < 0.001; 0 vs. 3, B = 2.48, p < 0.001; 0 vs. 4, B = 3.95; p < 0.001).

Conclusion

Our study confirms several risk factors of sleep-disordered breathing, namely male sex, overweight, and exposure to tobacco smoking, and found a positive association between habitual snoring and attention deficit/hyperactivity symptoms.

Sleep macro-architecture and micro-architecture in children born preterm with sleep disordered breathing

BACKGROUND

Both preterm birth and sleep disordered breathing (SDB) affect sleep in children. We compared the effects of SDB on sleep macro-architecture and micro-architecture in children born preterm (N = 50) and children born at term (N = 50). We hypothesized that sleep would be more disrupted in children born preterm.

METHODS

Polysomnographic studies matched for age (3-12 years) and SDB severity were analyzed. Sleep macro-architecture was assessed using standard criteria and micro-architecture was evaluated using spectral analysis of the electroencephalogram and slow wave activity (SWA) calculated for each sleep stage across the night.

RESULTS

Ex-preterm children (gestational age 29.3 ± 3.6 weeks, mean ± standard error of the mean) were not different from controls for demographic or respiratory parameters or sleep macro-architecture. Theta power in N2 tended to be higher for F4 (p < 0.05) and C4 (p < 0.07). In the second non-rapid eye movement period, SWA was significantly higher in the preterm group compared to the term group for both F4 and C4 (p < 0.05 for both).

CONCLUSIONS

Sleep micro-architecture in children born preterm showed increased theta power and SWA. These differences provide evidence of increased sleep debt and reduced dissipation of sleep debt across the night. Further studies are required to identify if these findings are related to impaired neurocognition and behavior.

Correlation of sleep microstructure with daytime sleepiness and cognitive function in young and middle-aged adults with obstructive sleep apnea syndrome

PURPOSE

To compare microstructural features of sleep in young and middle-aged adults with differing severities of obstructive sleep apnea syndrome (OSAS), and to investigate the relationship between sleep microstructural fragmentation and cognitive impairment, as well as daytime sleepiness, in these patients.

METHODS

A total of 134 adults with snoring (mean age, 37.54 ± 7.66 years) were classified into four groups based on apnea-hypopnea index: primary snoring, mild OSAS, moderate OSAS, and severe OSAS. Overnight polysomnography was performed to assess respiratory, sleep macrostructure (N1, N2, N3, and R), and sleep microstructure (arousal, cyclic alternating pattern [CAP]) parameters. Cognitive function and daytime sleepiness were assessed using Montreal Cognitive Assessment (MoCA) and Epworth Sleepiness Scale (ESS).

RESULTS

As OSAS severity increased, MoCA gradually decreased and ESS gradually increased. N1%, N2%, and N3% sleep were significantly different between the severe OSAS group and the primary snoring, mild OSAS, and moderate OSAS groups (all P < 0.05). Overall arousal index, respiratory-related arousal index, CAP time, CAP rate, phase A index, number of CAP cycles, and phase A average time differed significantly in the moderate and severe OSAS groups compared with the mild OSAS and primary snoring groups (all P < 0.05). The strongest correlations identified by stepwise multiple regression analysis were between phase A3 index and the MoCA and ESS scores.

CONCLUSIONS

Sleep microstructure exhibited significant fragmentation in patients with moderate and severe OSAS, which was associated with decreased MoCA and increased ESS scores. This suggests that phase A3 index is a sensitive indicator of sleep fragmentation in OSAS.