Sleep patterns and daytime sleepiness in adolescents and young adults with Williams syndrome

Short Report: Lack of Diurnal Variation in Salivary Cortisol Is Linked to Sleep Disturbances and Heightened Anxiety in Adolescents with Williams Syndrome

Objective: The aim of the current study was to examine the potential relationship between sleep patterns, cortisol levels, and anxiety profiles in adolescents with Williams Syndrome (WS) compared to typically developing adolescents. Method: Thirteen adolescents with WS and thirteen TD adolescents (age range 12–18 years) were recruited. Participants were provided with a “testing kit”, containing instructions for collecting data through a sleep diary, MotionWare actigraphy, the Childhood Sleep Habits Questionnaire (CSHQ), and the Spence Children’s Anxiety Scale, and a salivary cortisol collection kit. Results: Adolescents in the WS group did not show diurnal variation in salivary cortisol. Significantly higher scores were reported for two CSHQ subsections, night wakings and parasomnias, in the WS group. Regarding the actigraphy, only significantly longer sleep latency was observed in the WS group. In comparison to the TD group, the WS group had significantly higher anxiety. As expected, the TD group showed typical diurnal variation in cortisol, whereas the WS group showed a flattened cortisol profile throughout the day. Conclusions: From the developmental perspective, this study provides new data supporting the conclusion that sleep problems are not transient but continue to persist into adolescence in WS. Future studies ought to consider examining the role of cortisol and its interplay with anxiety levels and sleep problems across the lifespan in individuals with WS.

Sleep-related learning in Williams Syndrome and Down's Syndrome

This chapter addresses sleep research challenges for the study of neurodevelopmental disorders drawing upon two disorders such as Down Syndrome and Williams syndrome. General sleep problems are outlined here, however particular consideration is given to the syndrome-specific issues or challenges that may be crucial to advancing our understanding of sleep-related cognitive and behavioral issues.

Sleep's role in memory consolidation: What can we learn from atypical development?

Research conducted over the last century has suggested a role for sleep in the processes guiding healthy cognition and development, including memory consolidation. Children with intellectual and developmental disabilities (IDDs) tend to have higher rates of sleep disturbances, which could relate to behavior issues, developmental delays, and learning difficulties. While several studies examine whether sleep exacerbates daytime difficulties and attention deficits in children with IDDs, this chapter focuses on the current state of knowledge regarding sleep and memory consolidation in typically developing (TD) groups and those at risk for learning difficulties. In particular, this chapter summarizes the current literature on sleep-dependent learning across developmental disabilities, including Down syndrome, Williams syndrome, Autism Spectrum Disorder, and Learning Disabilities (Attention-Deficit/Hyperactivity Disorder and Dyslexia). We also highlight the gaps in the current literature and identify challenges in studying sleep-dependent memory in children with different IDDs. This burgeoning new field highlights the importance of considering the role of sleep in memory retention across long delays when evaluating children's memory processes. Further, an understanding of typical and atypical development can mutually inform recent theories of sleep's role in memory.

Psychopharmacology of Williams syndrome: safety, tolerability, and effectiveness

Introduction: Williams syndrome (WS) is a neurogenetic disorder characterized by a hyper-social personality, intellectual disability, and multiple medical co-morbidities. Psychiatric co-morbidities are also common. Since medical co-morbidities are common in this population, the risk-benefit of the use of psychiatric medications must be carefully considered and monitoring for safety and tolerability is needed.Areas covered: We review the cognitive profile and common medical co-morbidities in WS. We then discuss the common presentations of psychiatric disorders and review the available evidence on the use of psychiatric medications in WS. No prospective psychiatric medication trials have been conducted. We highlight the side effect profile of common psychiatric medications as they pertain to WS.Expert opinion: Psychiatric disorders can have a major effect on the quality of life of individuals with WS. The lack of long-term safety data and high likelihood of medical co-morbidities in WS make the judicious use of psychiatric medications more challenging; however, they can play an important role in decreasing distress and improving functioning. We provide recommendations for first- and second-line classes of medications based on our clinical experience and consideration of adverse effect profiles, as well as safety monitoring parameters at baseline and periodically.

Neurodevelopmental Disorders Commonly Presenting with Sleep Disturbances

There are multiple disorders of neurodevelopment that present with co-occurring sleep disturbances. Many of these neurodevelopmental disorders (NDD) include sleep disturbances in their diagnostic criteria. Neurobiological, genetic, and environmental factors overlap to cause different sleep disorders in individuals with NDD. Caregivers often present reporting either insomnia or hypersomnia, and based on the clinical history and findings from diagnostic tests, an appropriate diagnosis can be made. It is crucial that clinicians understand the different presentations of sleep disturbances in individuals with NDD.

Sleep characteristics and problems of 2-year-olds with Williams syndrome: relations with language and behavior

Background

Sleep problems have been shown to have a negative impact on language development and behavior for both typically developing children and children with a range of neurodevelopmental disorders. The relation of sleep characteristics and problems to language and behavior for children with Williams syndrome (WS) is unclear. The goal of this study was to address these relations for 2-year-olds with WS. Associations of nonverbal reasoning ability, nighttime sleep duration, and excessive daytime sleepiness with language ability and behavior problems were considered.

Method

Ninety-six 2-year-olds with genetically confirmed classic-length WS deletions participated. Parents completed the Pediatric Sleep Questionnaire, which includes a Sleep-Related Breathing Disorder (SRBD) scale with a subscale measuring excessive daytime sleepiness, to assess sleep characteristics and problems. Parents also completed the Child Behavior Checklist (CBCL) and the MacArthur-Bates Communicative Development Inventory: Words and Sentences to assess behavior problems and expressive vocabulary, respectively. Children completed the Mullen Scales of Early Learning to measure nonverbal reasoning and language abilities.

Results

Parents indicated that children slept an average of 10.36 h per night (SD = 1.09, range 7.3–13.3), not differing significantly from the mean reported by Bell and Zimmerman (2010) for typically developing toddlers (p = .787). Sixteen percent of participants screened positive for SRBD and 30% for excessive daytime sleepiness. Children who screened positive for SRBD had significantly more behavior problems on all CBCL scales than children who screened negative. Children with excessive daytime sleepiness had significantly more attention/hyperactivity, stress, and externalizing problems than those who did not have daytime sleepiness. Individual differences in parent-reported nighttime sleep duration and directly measured nonverbal reasoning abilities accounted for unique variance in expressive language, receptive language, and internalizing problems. Individual differences in parent-reported daytime sleepiness accounted for unique variance in externalizing problems.

Conclusions

The relations of nighttime sleep duration, positive screens for SRBD, and excessive daytime sleepiness to language and behavior in toddlers with WS parallel prior findings for typically developing toddlers. These results highlight the importance of screening young children with WS for sleep problems. Studies investigating the efficacy of behavioral strategies for improving sleep in children with WS are warranted.

Supplementary Information

The online version contains supplementary material available at 10.1186/s11689-020-09336-z.

Comparison of village dog and wolf genomes highlights the role of the neural crest in dog domestication

BACKGROUND

Domesticated from gray wolves between 10 and 40 kya in Eurasia, dogs display a vast array of phenotypes that differ from their ancestors, yet mirror other domesticated animal species, a phenomenon known as the domestication syndrome. Here, we use signatures persisting in dog genomes to identify genes and pathways possibly altered by the selective pressures of domestication.

RESULTS

Whole-genome SNP analyses of 43 globally distributed village dogs and 10 wolves differentiated signatures resulting from domestication rather than breed formation. We identified 246 candidate domestication regions containing 10.8 Mb of genome sequence and 429 genes. The regions share haplotypes with ancient dogs, suggesting that the detected signals are not the result of recent selection. Gene enrichments highlight numerous genes linked to neural crest and central nervous system development as well as neurological function. Read depth analysis suggests that copy number variation played a minor role in dog domestication.

CONCLUSIONS

Our results identify genes that act early in embryogenesis and can confer phenotypes distinguishing domesticated dogs from wolves, such as tameness, smaller jaws, floppy ears, and diminished craniofacial development as the targets of selection during domestication. These differences reflect the phenotypes of the domestication syndrome, which can be explained by alterations in the migration or activity of neural crest cells during development. We propose that initial selection during early dog domestication was for behavior, a trait influenced by genes which act in the neural crest, which secondarily gave rise to the phenotypes of modern dogs.

Use and Effectiveness of Sleep Medications by Parent Report in Individuals with Williams Syndrome

OBJECTIVE

Sleep disorders are common in individuals with Williams syndrome (WS), and sleep disturbance has a significant negative effect on attention, learning, and behavior. The use of sleep-inducing medicine in individuals with WS has not been widely investigated. The objective of this study was to evaluate the use and effectiveness of sleep medications among a large sample of individuals with WS by parent survey.

METHODS

A survey of the use and effectiveness of sleep medications was completed by 513 (of 2846) members of the Williams Syndrome Association. The online survey asked for the age at initiation, degree of effectiveness (helpful, somewhat helpful, and not helpful), and side effects.

RESULTS

One hundred thirty participants (25%) indicated that their family member with WS had taken medication to help with sleep. Melatonin was the most commonly reported medication taken for sleep, with 91% of parents reporting that it was "helpful" or "somewhat helpful" for their child with WS. Those who reported taking melatonin reported very few, if any, side effects.

CONCLUSION

This parent-completed survey is a preliminary study showing the positive benefit of melatonin for individuals with WS who have disrupted sleep. The findings support the need for further study of the use of melatonin, in addition to behavioral sleep aids, given evidence that sleep disturbance negatively influences cognition and behavior.

Sigma frequency dependent motor learning in Williams syndrome

There are two basic stages of fine motor learning: performance gain might occur during practice (online learning), and improvement might take place without any further practice (offline learning). Offline learning, also called consolidation, has a sleep-dependent stage in terms of both speed and accuracy of the learned movement. Sleep spindle or sigma band characteristics affect motor learning in typically developing individuals. Here we ask whether the earlier found, altered sigma activity in a neurodevelopmental disorder (Williams syndrome, WS) predicts motor learning. TD and WS participants practiced in a sequential finger tapping (FT) task for two days. Although WS participants started out at a lower performance level, TD and WS participants had a comparable amount of online and offline learning in terms of the accuracy of movement. Spectral analysis of WS sleep EEG recordings revealed that motor accuracy improvement is intricately related to WS-specific NREM sleep EEG features in the 8–16 Hz range profiles: higher 11–13.5 Hz z-transformed power is associated with higher offline FT accuracy improvement; and higher oscillatory peak frequencies are associated with lower offline accuracy improvements. These findings indicate a fundamental relationship between sleep spindle (or sigma band) activity and motor learning in WS.

Sleep phenotypes in infants and toddlers with neurogenetic syndromes

BACKGROUND

Although sleep problems are well characterized in preschool- and school-age children with neurogenetic syndromes, little is known regarding the early emergence of these problems in infancy and toddlerhood. To inform syndrome-specific profiles and targets for intervention, we compared parent-reported sleep problems in infants and toddlers with Angelman syndrome (AS), Williams syndrome (WS), and Prader-Willi syndrome (PWS) with patterns observed among same-aged typically developing (TD) controls.

METHODS

Mothers of 80 children (18 AS, 19 WS, 19 PWS, and 24 TD) completed the Brief Infant Sleep Questionnaire. Primary dependent variables included (1) sleep onset latency, (2) total sleep duration, (3) daytime and nighttime sleep duration, and (4) sleep problem severity, as measured by both maternal impression and National Sleep Foundation guidelines.

RESULTS

Sleep problems are relatively common in children with neurogenetic syndromes, with 41% of mothers reporting problematic sleep and 29% of children exhibiting abnormal sleep durations as per national guidelines. Across genetic subgroups, problems are most severe in children with AS and WS, particularly in relation to nighttime sleep duration. Although atypical sleep is characteristically reported in each syndrome later in development, infants and toddlers with PWS exhibited largely typical patterns, potentially indicating delayed onset of sleep problems in concordance with other medical features of PWS.

CONCLUSIONS

Our findings suggest that sleep problems in neurogenetic syndromes emerge as early as infancy and toddlerhood, with variable profiles across genetic subgroups. This work underscores the importance of early sleep screenings as part of routine medical care of neurosyndromic populations and the need for targeted, syndrome-sensitive treatment.

Increased overall cortical connectivity with syndrome specific local decreases suggested by atypical sleep-EEG synchronization in Williams syndrome

Williams syndrome (7q11.23 microdeletion) is characterized by specific alterations in neurocognitive architecture and functioning, as well as disordered sleep. Here we analyze the region, sleep state and frequency-specific EEG synchronization of whole night sleep recordings of 21 Williams syndrome and 21 typically developing age- and gender-matched subjects by calculating weighted phase lag indexes. We found broadband increases in inter- and intrahemispheric neural connectivity for both NREM and REM sleep EEG of Williams syndrome subjects. These effects consisted of increased theta, high sigma, and beta/low gamma synchronization, whereas alpha synchronization was characterized by a peculiar Williams syndrome-specific decrease during NREM states (intra- and interhemispheric centro-temporal) and REM phases of sleep (occipital intra-area synchronization). We also found a decrease in short range, occipital connectivity of NREM sleep EEG theta activity. The striking increased overall synchronization of sleep EEG in Williams syndrome subjects is consistent with the recently reported increase in synaptic and dendritic density in stem-cell based Williams syndrome models, whereas decreased alpha and occipital connectivity might reflect and underpin the altered microarchitecture of primary visual cortex and disordered visuospatial functioning of Williams syndrome subjects.

Capacity to improve fine motor skills in Williams syndrome

BACKGROUND

Individuals with Williams syndrome (WS) are known to have difficulties in carrying out fine motor movements; however, a detailed behavioural profile of WS in this domain is still missing. It is also unknown how great the capacity to improve these skills with focused and extensive practice is.

METHOD

We studied initial performance and learning capacity in a sequential finger tapping (FT) task in WS and in typical development. Improvement in the FT task has been shown to be sleep dependent. WS subjects participating in the current study have also participated in earlier polysomnography studies, although not directly related to learning.

RESULTS

WS participants presented with great individual variability. In addition to generally poor initial performance, learning capacity was also greatly limited in WS. We found indications that reduced sleep efficiency might contribute to this limitation.

CONCLUSIONS

Estimating motor learning capacity and the depth of sleep disorder in a larger sample of WS individuals might reveal important relationships between sleep and learning, and contribute to efficient intervention methods improving skill acquisition in WS.

The Importance of Sleep: Attentional Problems in School-Aged Children With Down Syndrome and Williams Syndrome

In typically developing (TD) children, sleep problems have been associated with day-time attentional difficulties. Children with developmental disabilities often suffer with sleep and attention problems, yet their relationship is poorly understood. The present study investigated this association in school-aged children with Down syndrome (DS) and Williams syndrome (WS). Actigraphy and pulse oximetry assessed sleep and sleep-disordered breathing respectively, and attention was tested using a novel visual Continuous Performance Task (CPT).Attentional deficits were evident in both disorder groups. In the TD group, higher scores on the CPT were related to better sleep quality, higher oxyhemoglobin saturation (SpO2), and fewer desaturation events. Sleep quality, duration, and SpO2 variables were not related to CPT performance for children with DS and WS.

Sleep in Neurodevelopmental Disorders

Individuals with intellectual and developmental disabilities (IDD) experience sleep problems at higher rates than the general population. Although individuals with IDD are a heterogeneous group, several sleep problems cluster within genetic syndromes or disorders. This review summarizes the prevalence of sleep problems experienced by individuals with Angelman syndrome, Cornelia de Lange syndrome, Cri du Chat syndrome, Down syndrome, fragile X syndrome, Prader-Willi syndrome, Smith-Magenis syndrome, Williams syndrome, autism spectrum disorder, and idiopathic IDD. Factors associated with sleep problems and the evidence for sleep treatments are reviewed for each neurodevelopmental disorder. Sleep research advancements in neurodevelopmental disorders are reviewed, including the need for consistency in defining and measuring sleep problems, considerations for research design and reporting of results, and considerations when evaluating sleep treatments.

Performance on the Kaufman Brief Intelligence Test-2 by Children With Williams Syndrome

We describe the performance of 292 4- to 17-year-olds with Williams syndrome (WS) on the Kaufman Brief Intelligence Test-2 (KBIT-2; Kaufman & Kaufman, 2004). Mean IQ Composite, Verbal standard score (SS), and Nonverbal SS were in the borderline range relative to the general population, with variability similar to the general population. Correlations between SSs and CA were close to 0, with no significant sex differences. There was a significant effect of maternal education on Verbal SS. The KBIT-2 appropriately captures the full range of performance of 8- to 17-year-olds with WS for the abilities measured and of all but the very lowest-functioning 5- to 7-year-olds. However, the KBIT-2 does not contain easy enough items to adequately assess the abilities of the lowest quartile of 4-year-olds.

A cross-syndrome study of the differential effects of sleep on declarative memory consolidation in children with neurodevelopmental disorders

Sleep plays an active role in memory consolidation. Because children with Down syndrome (DS) and Williams syndrome (WS) experience significant problems with sleep and also with learning, we predicted that sleep‐dependent memory consolidation would be impaired in these children when compared to typically developing (TD) children. This is the first study to provide a cross‐syndrome comparison of sleep‐dependent learning in school‐aged children. Children with DS (n = 20) and WS (n = 22) and TD children (n = 33) were trained on the novel Animal Names task where they were taught pseudo‐words as the personal names of ten farm and domestic animals, e.g. Basco the cat, with the aid of animal picture flashcards. They were retested following counterbalanced retention intervals of wake and sleep. Overall, TD children remembered significantly more words than both the DS and WS groups. In addition, their performance improved following night‐time sleep, whereas performance over the wake retention interval remained stable, indicating an active role of sleep for memory consolidation. Task performance of children with DS did not significantly change following wake or sleep periods. However, children with DS who were initially trained in the morning continued to improve on the task at the following retests, so that performance on the final test was greater for children who had initially trained in the morning than those who trained in the evening. Children with WS improved on the task between training and the first retest, regardless of whether sleep or wake occurred during the retention interval. This suggests time‐dependent rather than sleep‐dependent learning in children with WS, or tiredness at the end of the first session and better performance once refreshed at the start of the second session, irrespective of the time of day. Contrary to expectations, sleep‐dependent learning was not related to baseline level of performance. The findings have significant implications for educational strategies, and suggest that children with DS should be taught more important or difficult information in the morning when they are better able to learn, whilst children with WS should be allowed a time delay between learning phases to allow for time‐dependent memory consolidation, and frequent breaks from learning so that they are refreshed and able to perform at their best.

Sleep in high-functioning children with autism: longitudinal developmental change and associations with behavior problems

Sleep disturbance is common in autism spectrum disorder (ASD), but longitudinal trajectories are poorly defined. This study measured sleep disturbance at baseline and 1 year later examining change over time and associated problem behaviors. Participants were 84 gender-matched children, aged between 7 and 12 years at baseline; 46 children were diagnosed with ASD, and 38 were typically developing (TYP) children. Parent reports on a range of scales were collected. The ASD group had more sleep disturbance than the TYP group. Sleep disturbance decreased over the year in children with ASD, but not in TYP children. Reduced sleep disturbance was associated with improved social ability. Sleep disturbance at baseline predicted later anxiety. Findings indicated different trajectories of sleep disturbance in ASD, and the implications are discussed.

Aging and sleep in Williams syndrome: accelerated sleep deterioration and decelerated slow wave sleep decrement

Specific developmental and aging trajectories characterize sleep electroencephalogram (EEG) of typically developing (TD) subjects. Williams syndrome (WS) is marked by sleep alterations and accelerated aging of several anatomo-functional and cognitive measures. Here we test the hypothesis of a premature aging of sleep in WS. Age-related changes of home recorded sleep EEG of 42 subjects (21 WS, 21 age- and gender matched TD subjects, age: 6-29 years) were tested by Pearson correlations and homogeneity-of-slopes analysis. Typical developmental/aging effects of sleep EEGs were observed in TD subjects. Accelerated aging in WS was confirmed by overall sleep/wake measures. Specifically, premature aging was evident in accelerated age-dependent declines in WS subjects' sleep efficiency, as well as in steeper age-related rises in wakefulness and wake after sleep onset (WASO) of the WS group. In contrast, NREM sleep-related measures indicated atypical decelerations of the developmental trends of WS subjects, characterized by the slowing down of the age-related slow wave sleep (SWS) declines mirrored by the lack of age-dependent increase in Stage 2 (S2) sleep. Age-effects in sleep EEG power spectra were not different among the groups. Objectively measured sleep disruption of subjects with WS is age-dependent and increasing with age. Moreover, these data suggest atypical pre- and postpubertal neural development in WS, with sleep/wake balance and REM sleep time indicating accelerated aging while NREM sleep composition revealing signs of an as yet unidentified, perhaps compensatory developmental delay.

Sleep, plasticity and the pathophysiology of neurodevelopmental disorders: the potential roles of protein synthesis and other cellular processes

Sleep is important for neural plasticity, and plasticity underlies sleep-dependent memory consolidation. It is widely appreciated that protein synthesis plays an essential role in neural plasticity. Studies of sleep-dependent memory and sleep-dependent plasticity have begun to examine alterations in these functions in populations with neurological and psychiatric disorders. Such an approach acknowledges that disordered sleep may have functional consequences during wakefulness. Although neurodevelopmental disorders are not considered to be sleep disorders per se, recent data has revealed that sleep abnormalities are among the most prevalent and common symptoms and may contribute to the progression of these disorders. The main goal of this review is to highlight the role of disordered sleep in the pathology of neurodevelopmental disorders and to examine some potential mechanisms by which sleep-dependent plasticity may be altered. We will also briefly attempt to extend the same logic to the other end of the developmental spectrum and describe a potential role of disordered sleep in the pathology of neurodegenerative diseases. We conclude by discussing ongoing studies that might provide a more integrative approach to the study of sleep, plasticity, and neurodevelopmental disorders.

Sleep problems and language development in toddlers with Williams syndrome

Sleep and related maternal beliefs were assessed in a narrow age range of 18 children with Williams syndrome (WS) and 18 typically developing (TD) children. WS is a rare genetic disorder characterised by a complex physical, cognitive and behavioural phenotype. High prevalence of sleep difficulties in older children and adults with WS have been reported. Parents completed 6 questionnaires: the Brief Infant Sleep Questionnaire, Infant Sleep Vignettes Interpretation Scale, Pittsburgh Sleep Quality Index of Parents, Child Behaviour Checklist, MacArthur Communicative Development Inventory for Infants - Words and Gestures, and the Major (ICD-10) Depression Inventory. Compared to TD children, those with WS had shorter night sleep, more night wakings and wakefulness according to parental report. Regression analyses revealed that a proportion of the variance in language development scores in WS children could be explained by night sleep duration. Compared to control parents, the mothers of the WS group were more likely to describe their child's sleep as problematic and had higher rates of involvement with child sleep, yet they had a lesser tendency to interpret sleep problems as signs of distress and a greater tendency to emphasise limit setting. Approximately half of both groups of mothers experienced poor sleep quality. This was also related to maternal mood, and night wakefulness in the children with WS. This is the first study to quantify sleep difficulties in young children with WS in a narrow age range using maternal report. The possible negative effects on maternal sleep and mood, and the link between night sleep and language development in young children with WS, requires further detailed investigation.

Cross syndrome comparison of sleep problems in children with Down syndrome and Williams syndrome

Based on previous findings of frequent sleep problems in children with Down syndrome (DS) and Williams syndrome (WS), the present study aimed to expand our knowledge by using parent report and actigraphy to define sleep problems more precisely in these groups. Twenty-two school-aged children with DS, 24 with WS and 52 typically developing (TD) children took part in the study. Each child wore an actiwatch for a minimum of four nights and parents completed the Children's Sleep Habits Questionnaire (CSHQ). Sleep problems were common in both developmental disorders. Children with DS had the greatest sleep disruption, with frequent and longer night wakings as well as restlessness. Parents reported symptoms of sleep-disordered breathing and a range of other problems including grinding teeth, bedtime resistance and sleep anxiety. Children with WS had problems initiating sleep and parents also reported bed-wetting and body pain. Despite these problems, the mean actual sleep time, as measured by actigraphy, did not differ between the three groups. CSHQ reports were in agreement with actigraphy for children's sleep duration, but this was not the case for sleep latency, restlessness and the night wakings variables. Sleep problems in DS and WS are common and appear to be syndrome-specific. Due to the inaccuracy of parent report, it is recommended that children at risk undergo objective measures of sleep assessment.

Co-morbidity of complex genetic disorders and hypersomnias of central origin: lessons from the underlying neurobiology of wake and sleep

Appropriate wake and sleep cycles are important to physical well-being, and are modulated by neuronal networks in the brain. A variety of medical conditions can disrupt sleep or cause excessive daytime sleepiness. Clinical diagnostic classification schemes have historically lumped genetic disorders together into a category that considers the sleep dysfunction to be secondary to a medical condition. The unique nature of sleep endophenotypes that occur more frequently in particular genetic disorders has been underappreciated. Increased understanding of the pathophysiology of wake/sleep dysfunction in rare genetic disorders could inform studies of the neurological mechanisms that underlie more common forms of wake and sleep dysfunction. In this review, we highlight genetic developmental disorders in which sleep endophenotypes have been described, and then consider genetic neurodegenerative disorders with sleep characteristics that set them apart from the disruptions to sleep that are typically associated with aging and dementia.

Sleep EEG fingerprints reveal accelerated thalamocortical oscillatory dynamics in Williams syndrome

Sleep EEG alterations are emerging features of several developmental disabilities, but detailed quantitative EEG data on the sleep phenotype of patients with Williams syndrome (WS, 7q11.23 microdeletion) is still lacking. Based on laboratory (Study I) and home sleep records (Study II) here we report WS-related features of the patterns of antero-posterior 8-16 Hz non-rapid-eye-movement (NREM) sleep EEG power distributions. Participants in Study I were 9 WS and 9 typically developing (TD) controls matched for age (14-29 years) and sex, and sleeping for two consecutive nights in the laboratory. WS participants were characterized by region-independent decreases in 10.50-12.50 Hz and central increases in 14.75-15.75 Hz EEG power. Region-independent decreases and increases in z-scores of the spectra were observed in the 10.25-12.25 Hz and 14-16 Hz ranges, respectively. Moreover, in the EEG spectra of participants with WS a lower probability for the emergence of a frontally dominant peak was observed. Parietal fast sigma peaks and the antero-posterior shifts in power distributions were of higher frequencies in WS (~1 Hz difference). A 1 year follow-up of 9 WS and 3 TD participants, as well as their inclusion into larger samples (20 WS and 20 TD, age: 6-29 years) of a two-night ambulatory home polysomnography study confirmed the WS-specific decrease in alpha/low sigma power (8-11.75 Hz) and the pattern of z-score differences (decreases: 8.50-11.25 Hz; increases: 13.5-14 Hz), including the antero-posterior shifts in power distribution (0.5 Hz) and some features of the spectral peaks. Altogether these data suggest a decrease in alpha/low sigma power, as well as a redistribution of NREM sleep 8-16 Hz EEG power toward the higher frequencies and/or a higher frequency of NREM sleep thalamocortical oscillations in WS.

Pain disrupts sleep in children and youth with intellectual and developmental disabilities

Both chronic pain and sleep problems are common for children with intellectual and developmental disabilities (IDD). Although one study has revealed a relationship between having a medical condition and sleep problems in this population, the role of pain was not examined independently. Thus, the goal of this study was to clarify the specific role of pain in children's sleep problems. Caregivers of 123 children with IDD (67 male; mean age = 10 years, 7 months (SD = 49.7 months)) completed the Children's Sleep Habits Questionnaire (CHSQ) and provided information about children's pain, function and demographic characteristics. Children were grouped as having: No Pain (86), Treated Pain (21), or Untreated Pain (16). A Multivariate Analysis of Variance (MANOVA) indicated children who had pain had significantly more sleep problems overall (F(16, 222) = 2.2, p = .005), and more Night Wakings (F(2, 118) = 3.1, p = .05), Parasomnias (F(2, 118) = 5.0, p = .009) and Sleep Disordered Breathing (F(2, 118) = 5.1, p = .008) in particular. The pattern of sleep problems varied due to whether the child was taking pain medication. Children with pain also had significantly shorter typical sleep duration (F(2, 112) = 3.5, p = 0.035). The presence of sleep problems did not vary due to functional level or whether children were taking sleep medications. However, parents of children who were taking sleep medications reported that both Bedtime Resistance (F(1, 121) = 5.7, p = .019) and Sleep Duration (F(1, 121) = 6.0, p = .016) were more problematic for them. This data indicates pain disrupts sleep in children with IDD even when it is being managed pharmacologically, suggesting pain treatment may not be effective. These results suggest that pain should be considered during evaluation and management of sleep problems in children with IDD.

Sleep assessments in healthy school-aged children using actigraphy: concordance with polysomnography

Actigraphic (ACT) recordings are used widely in schoolchildren as a less intrusive and more extended approach to evaluation of sleep problems. However, critical assessment of the validity and reliability of ACT against overnight polysomnography (NPSG) are unavailable. Thus, we explored the degree of concordance between NPSG and ACT in school-aged children to delineate potential ACT boundaries when interpreting pediatric sleep. Non-dominant wrist ACT was recorded simultaneously with NPSG in 149 healthy school-aged children (aged 4.1-8.8 years, 41.7% boys, 80.4% Caucasian) recruited from the community. Analyses were limited to the Actiware (MiniMitter-64) calculated parameters originating from 1-min epoch sampling and medium sensitivity threshold value of 40; i.e. sleep period time (SPT), total sleep time (TST) and wake after sleep onset (WASO). SPT was not significantly different between ACT and NPSG. However, ACT underestimated TST significantly by 32.2±33.4 min and overestimated WASO by 26.3±34.4 min. The decreased precision of ACT was also evident from moderate to small concordance correlation coefficients (0.47 for TST and 0.09 for WASO). ACT in school-aged children provides reliable assessment of sleep quantity, but is relatively inaccurate during determination of sleep quality. Thus, caution is advocated in drawing definitive conclusions from ACT during evaluation of the sleep-disturbed child.

Atypical sleep architecture and altered EEG spectra in Williams syndrome

BACKGROUND

Williams syndrome (WS) is a neurodevelopmental genetic disorder characterised by physical abnormalities and a distinctive cognitive profile with intellectual disabilities (IDs) and learning difficulties.

METHODS

In our study, nine adolescents and young adults with WS and 9 age- and sex-matched typically developing (TD) participants underwent polysomnography. We examined sleep architecture, leg movements and the electroencephalogram (EEG) spectra of specific frequency bands at different scalp locations.

RESULTS

We found an atypical, WS characteristic sleep pattern with decreased sleep time, decreased sleep efficiency, increased wake time after sleep onset, increased non-rapid eye movement percentage, increased slow wave sleep, decreased rapid eye movement sleep percentage, increased number of leg movements and irregular sleep cycles. Patients with WS showed an increased delta and slow wave activity and decreased alpha and sigma activity in the spectral analysis of the EEG.

CONCLUSIONS

Sleep maintenance and organisation are significantly affected in WS, while EEG spectra suggest increases in sleep pressure.

Characterisation of sleep problems in children with Williams syndrome

Sleep is critical to optimal daytime functioning, learning and general health. In children with established developmental disorders sleep difficulties may compound existing learning difficulties. The purpose of the present study was to evaluate the prevalence and syndrome specificity of sleep problems in Williams syndrome (WS), a neurodevelopmental disorder affecting around 1 in 20,000 live births. Parents of 64 children with WS, aged 6-12 years, and 92 age matched healthy controls were surveyed about their child's sleep habits. The Child Sleep Habits Questionnaire, general health and background information were collected from the parents. Ninety seven percent of parents reported that their children had sleep problems and reported a high prevalence of sleep difficulties: greater bedtime resistance, sleep anxiety, night waking and daytime sleepiness. This is the first study to our knowledge to survey sleep problems in a large cohort of school age children with WS. Sleep problems in children with learning difficulties are often amendable to treatment if diagnosed early. Furthermore the negative impact of sleep disturbances on daytime behaviour and learning should be measured before diagnoses of behaviourally defined disorders are considered.

Introduction: Williams syndrome

In the nearly 50 years since the description of Williams syndrome by [Williams et al. (1961); Circulation 24:1311-1318], the focus of scientific inquiry has shifted from identification, definition, and description of the syndrome in small series to genotype-phenotype correlation, pathophysiologic investigation in both humans and in animal models, and therapeutic outcomes in large cohorts. Study of this rare syndrome has provided insight into the structure and function of the extracellular matrix, has contributed to understanding of genomic structure and rearrangement, and is beginning to elucidate genetic underpinnings of learning, language, and behavior. The results of current research not only recommend interventions that can be implemented now, but also identify areas requiring additional investigation, and suggest future therapeutic approaches.

Cutoffs, norms, and patterns of comorbid difficulties in children with developmental disabilities on the Baby and Infant Screen for Children with aUtIsm Traits (BISCUIT-Part 2)

Behavioral symptoms of comorbid psychopathology of 651 children 17-37 months of age who were at risk for developmental disabilities were studied using the BISCUIT-Part 2. In Study 1, norms and cutoff scores were established for this new scale on this sample. In Study 2, frequency of response on the 52 items measured was reported. Problems in eating and sleep were the most common with just over 15% of the sample experiencing these difficulties of either a moderate or severe nature. For severe problems, the most commonly reported difficulties were inattention/impulsivity, and tantrums/conduct behavior problems. Implications of this scale and these data for early identification of behavior disorders in atypically developing children are discussed.