Young children with Down syndrome show normal development of circadian rhythms, but poor sleep efficiency: a cross-sectional study across the first 60 months of life

Neuronal oscillations in cognition: Down syndrome as a model of mouse to human translation

Down syndrome (DS), a prevalent cognitive disorder resulting from trisomy of human chromosome 21 (Hsa21), poses a significant global health concern. Affecting approximately 1 in 800 live births worldwide, DS is the leading genetic cause of intellectual disability and a major predisposing factor for early-onset Alzheimer's dementia. The estimated global population of individuals with DS is 6 million, with increasing prevalence due to advances in DS health care. Global efforts are dedicated to unraveling the mechanisms behind the varied clinical outcomes in DS. Recent studies on DS mouse models reveal disrupted neuronal circuits, providing insights into DS pathologies. Yet, translating these findings to humans faces challenges due to limited systematic electrophysiological analyses directly comparing human and mouse. Additionally, disparities in experimental procedures between the two species pose hurdles to successful translation. This review provides a concise overview of neuronal oscillations in human and rodent cognition. Focusing on recent DS mouse model studies, we highlight disruptions in associated brain function. We discuss various electrophysiological paradigms and suggest avenues for exploring molecular dysfunctions contributing to DS-related cognitive impairments. Deciphering neuronal oscillation intricacies holds promise for targeted therapies to alleviate cognitive disabilities in DS individuals.

An investigation of sleep problems, gastrointestinal symptoms, comorbid psychopathology and challenging behavior in children and adolescents with Down Syndrome

BACKGROUND

Down syndrome (DS) is one of the most common chromosomal abnormalities, and children with DS have increased risks of receiving diagnoses of specific comorbidities.

AIMS

This study aimed to assess the frequencies and relationships between sleep problems, gastrointestinal (GI) symptoms, comorbid psychopathology, and challenging behavior.

METHODS AND PROCEDURES

The Children's Sleep Habits Questionnaire, Gastrointestinal Symptom Inventory, Autism Spectrum Disorder-Comorbid for Children, and Behavior Problems Inventory-Short Form were completed by 123 parents of children and adolescents with DS.

OUTCOMES AND RESULTS

The frequency of GI symptoms was 74.8 %, with high frequencies also found for: sleep problems (100 %), challenging behavior (100 %), and moderate to severe levels of comorbid psychopathology (tantrum=80 %; repetitive behavior=63 %; avoidant behavior=82 %; worry/depressed=61 %; conduct behavior=100 %; over-eating=100 %; under-eating=100 %). A significant moderate correlation was found between total GI symptoms and self-injurious behavior frequency. Children who presented with abdominal pain engaged in self-injurious behavior more frequently than those with no abdominal pain.

CONCLUSIONS AND IMPLICATIONS

Findings indicated a high frequency of sleep problems, comorbid psychopathology, GI symptoms, and challenging behavior and demonstrated a relationship between GI symptoms and self-injurious behavior in children and adolescents with DS. This research illustrated the importance of investigating comorbid conditions in individuals with DS. WHAT THIS PAPER ADDS?: Down Syndrome (DS) is a genetic condition characterized by trisomy 21 and is a leading cause of intellectual disability worldwide. The prevalence of DS is commonly associated with advanced maternal age and is associated with multiple comorbid conditions. The current study aimed to investigate the frequency of and relationship between sleep problems, gastrointestinal symptoms, comorbid psychopathology, and challenging behavior in children and adolescents with DS. High-frequency levels were found for sleep problems (100 %), challenging behavior (100 %), gastrointestinal symptoms (74.8 %), and moderate to severe levels of the different comorbid psychopathologies (tantrum=80 %; repetitive behavior=63 %; avoidant behavior=82 %; worry/depressed=61 %; conduct behavior=100 %; over-eating=100 %; under-eating=100 %). Results indicated a significant difference in self-injurious behavior frequency between individuals who presented with abdominal pain and those who did not. This study is the first to investigate the relationship of multiple comorbid conditions in a sample of children with DS. This paper adds to the literature by demonstrating the frequency of a number of comorbid conditions in children and adolescents with DS. The paper also adds novel findings to the literature by investigating the relationships between comorbid conditions in this population. The findings of this paper highlighted the frequency and comorbidities that exist between gastrointestinal symptoms, sleep problems, comorbid psychopathology, and challenging behavior. Analyses indicated that those who presented with abdominal pain, engaged in self-injurious behavior more frequently. Sleep problems, gastrointestinal symptoms, comorbid psychopathology, and challenging behavior in children and adolescents with Down Syndrome.

Exploring an objective measure of overactivity in children with rare genetic syndromes

BACKGROUND

Overactivity is prevalent in several rare genetic neurodevelopmental syndromes, including Smith-Magenis syndrome, Angelman syndrome, and tuberous sclerosis complex, although has been predominantly assessed using questionnaire techniques. Threats to the precision and validity of questionnaire data may undermine existing insights into this behaviour. Previous research indicates objective measures, namely actigraphy, can effectively differentiate non-overactive children from those with attention-deficit hyperactivity disorder. This study is the first to examine the sensitivity of actigraphy to overactivity across rare genetic syndromes associated with intellectual disability, through comparisons with typically-developing peers and questionnaire overactivity estimates.

METHODS

A secondary analysis of actigraphy data and overactivity estimates from The Activity Questionnaire (TAQ) was conducted for children aged 4-15 years with Smith-Magenis syndrome (N=20), Angelman syndrome (N=26), tuberous sclerosis complex (N=16), and typically-developing children (N=61). Actigraphy data were summarized using the M10 non-parametric circadian rhythm variable, and 24-hour activity profiles were modelled via functional linear modelling. Associations between actigraphy data and TAQ overactivity estimates were explored. Differences in actigraphy-defined activity were also examined between syndrome and typically-developing groups, and between children with high and low TAQ overactivity scores within syndromes.

RESULTS

M10 and TAQ overactivity scores were strongly positively correlated for children with Angelman syndrome and Smith-Magenis syndrome. M10 did not substantially differ between the syndrome and typically-developing groups. Higher early morning activity and lower evening activity was observed across all syndrome groups relative to typically-developing peers. High and low TAQ group comparisons revealed syndrome-specific profiles of overactivity, persisting throughout the day in Angelman syndrome, occurring during the early morning and early afternoon in Smith-Magenis syndrome, and manifesting briefly in the evening in tuberous sclerosis complex.

DISCUSSION

These findings provide some support for the sensitivity of actigraphy to overactivity in children with rare genetic syndromes, and offer syndrome-specific temporal descriptions of overactivity. The findings advance existing descriptions of overactivity, provided by questionnaire techniques, in children with rare genetic syndromes and have implications for the measurement of overactivity. Future studies should examine the impact of syndrome-related characteristics on actigraphy-defined activity and overactivity estimates from actigraphy and questionnaire techniques.

Sleep and Circadian Disturbances in Children With Neurodevelopmental Disorders

Sleep problems are highly prevalent in those with neurodevelopmental disorders (NDDs). We propose this is secondary to multiple factors that directly and indirectly negatively impact sleep and circadian processes in those with NDDs, which in turn, further perturbs development, resulting in a "developmental and sleep/circadian-related encephalopathy." In this review, we discuss select NDDs with known or suspected sleep and circadian phenotypes. We also highlight important considerations when evaluating and treating sleep and circadian disorders in these populations.

Behavioural sleep problems in children and adults with intellectual disabilities: An integrative literature review

BACKGROUND

People with intellectual disabilities are more likely to experience sleep problems, which can affect quality of life, physical health, mental health and well-being.

METHODS

An integrative literature review was conducted to investigate what is known about behavioural sleep disturbances in people with an intellectual disability. The search used the following databases: Scopus, PsycInfo and Cinahl, to find papers published since 2015.

RESULTS

Within intellectual disability research, sleep appears as a common issue due to its high prevalence, negative relationships with an individual's physical and mental health, their quality of life, and impact of sleep problems on family or carers. The growing evidence base appears to support the use of behavioural, lifestyle and pharmacological interventions to improve sleep in people with an intellectual disability.

CONCLUSION

A wide array of literature provides evidence that people with intellectual disabilities are affected by and need support with their sleep.

RCAN1 knockout and overexpression recapitulate an ensemble of rest-activity and circadian disruptions characteristic of Down syndrome, Alzheimer's disease, and normative aging

BACKGROUND

Regulator of calcineurin 1 (RCAN1) is overexpressed in Down syndrome (DS), but RCAN1 levels are also increased in Alzheimer's disease (AD) and normal aging. AD is highly comorbid among individuals with DS and is characterized in part by progressive neurodegeneration that resembles accelerated aging. Importantly, abnormal RCAN1 levels have been demonstrated to promote memory deficits and pathophysiology that appear symptomatic of DS, AD, and aging. Anomalous diurnal rest-activity patterns and circadian rhythm disruptions are also common in DS, AD, and aging and have been implicated in facilitating age-related cognitive decline and AD progression. However, no prior studies have assessed whether RCAN1 dysregulation may also promote the age-associated alteration of rest-activity profiles and circadian rhythms, which could in turn contribute to neurodegeneration in DS, AD, and aging.

METHODS

The present study examined the impacts of RCAN1 deficiency and overexpression on the photic entrainment, circadian periodicity, intensity and distribution, diurnal patterning, and circadian rhythmicity of wheel running in young (3-6 months old) and aged (9-14 months old) mice of both sexes.

RESULTS

We found that daily RCAN1 levels in the hippocampus and suprachiasmatic nucleus (SCN) of light-entrained young mice are generally constant and that balanced RCAN1 expression is necessary for normal circadian locomotor activity rhythms. While the light-entrained diurnal period was unaltered, RCAN1-null and RCAN1-overexpressing mice displayed lengthened endogenous (free-running) circadian periods like mouse models of AD and aging. In light-entrained young mice, RCAN1 deficiency and overexpression also recapitulated the general hypoactivity, diurnal rest-wake pattern fragmentation, and attenuated amplitudes of circadian activity rhythms reported in DS, preclinical and clinical AD, healthily aging individuals, and rodent models thereof. Under constant darkness, RCAN1-null and RCAN1-overexpressing mice displayed altered locomotor behavior indicating circadian clock dysfunction. Using the Dp(16)1Yey/+ (Dp16) mouse model for DS, which expresses three copies of Rcan1, we found reduced wheel running activity and rhythmicity in both light-entrained and free-running young Dp16 mice like young RCAN1-overexpressing mice. Critically, these diurnal and circadian deficits were rescued in part or entirely by restoring Rcan1 to two copies in Dp16 mice. We also found that RCAN1 deficiency but not RCAN1 overexpression altered protein levels of the clock gene Bmal1 in the SCN.

CONCLUSIONS

Collectively, this study's findings suggest that both loss and aberrant gain of RCAN1 precipitate anomalous light-entrained diurnal and circadian activity patterns emblematic of DS, AD, and possibly aging.

Melatonin as an immunomodulator in children with Down syndrome

BACKGROUND

Down syndrome (DS) is a disorder characterised by marked immune dysfunction, increased mortality from sepsis, chronic inflammation, increased oxidative stress, sleep disturbance and possibly abnormal endogenous melatonin levels. Melatonin has a myriad of immune functions, and we hypothesised that this therapeutic agent could modulate the innate immune system in this cohort.

METHODS

We investigated neutrophil and monocyte function (CD11b, TLR4 expression by flow cytometry), genes involved in TLR signalling (MyD88, IRAK4, TRIF), the inflammasome (NLRP3, IL-1β), and circadian rhythm (BMAL, CLOCK, CRY) by qPCR, and inflammatory cytokines (IL-2, IL-6, IL-8, IL-18, IL-1β, TNF-α, IFN-γ, IL-10, IL-1ra, VEGF, Epo, GM-CSF) by enzyme-linked immunosorbent assay (ELISA) following immunomodulation with LPS endotoxin and melatonin. 47 children with DS and 23 age- and sex-matched controls were recruited.

RESULTS

We demonstrated that melatonin has several significant effects by reducing CD11b and TLR4 expression, attenuating TLR signalling, genes involved in the inflammasome and has the potential to reduce LPS-induced inflammatory responses.

CONCLUSIONS

Immunomodulatory effects of melatonin were found in both paediatric cohorts with more marked effects in the children with DS. Melatonin mediates immune response through a wide array of mechanisms and this immunomodulator may buffer the inflammatory response by regulating pro and anti-inflammatory signalling.

IMPACT

We highlight that melatonin mediates its immune response through a wide array of mechanisms, its effects appear to be dose dependant and children with Down syndrome may be more receptive to treatment with it. Immunomodulatory effects of melatonin were demonstrated with marked effects in the children with Down syndrome with a reduction of MyD88, IL-1ß and NLRP3 expression in whole-blood samples. Melatonin is a proposed anti-inflammatory agent with a well-established safety profile, that has the potential for mitigation of pro- and anti-inflammatory cytokines in paediatric Down syndrome cohorts, though further clinical trials are warranted.

Circadian Sleep-Activity Rhythm across Ages in Down Syndrome

Across all ages, individuals with Down syndrome (DS) experience high rates of sleep problems as well as cognitive impairments. This study sought to investigate whether circadian rhythm disruption was also experienced by people with DS and whether this kind of sleep disorder may be correlated with cognitive performance. A cross-sectional study of 101 participants (58 with DS, 43 with typical development) included individuals in middle childhood (6–10 years old), adolescence (11–18 years old), and young adulthood (19–26 years old). Sleep and markers of circadian timing and robustness were calculated using actigraphy. Cognitive and behavioral data were gathered via a novel touchscreen battery (A-MAP^TM, Arizona Memory Assessment for Preschoolers and Special Populations) and parent questionnaire. Results indicated that children and adolescents with DS slept the same amount as peers with typical development, but significant group differences were seen in phase timing. The circadian robustness markers, interdaily stability and intradaily variability of sleep-wake rhythms, were healthiest for children regardless of diagnostic group and worst for adults with DS. Amplitude of the 24-h activity profile was elevated for all individuals with DS. In analyses of the correlations between sleep quality, rhythms, and cognition in people with DS, interdaily stability was positively correlated with reaction time and negatively correlated with verbal and scene recall, a finding that indicates increased stability may paradoxically correlate with poorer cognitive outcomes. Further, we found no relations with sleep efficiency previously found in preschool and adult samples. Therefore, the current findings suggest that a thorough examination of sleep disorders in DS must take into account age as well as circadian robustness to better understand sleep-cognitive correlations in this group.

Actigraphy in sleep research with infants and young children: Current practices and future benefits of standardized reporting

Actigraphy is a cost-efficient method to estimate sleep-wake patterns over long periods in natural settings. However, the lack of methodological standards in actigraphy research complicates the generalization of outcomes. A rapidly growing methodological diversity is visible in the field, which increasingly necessitates the detailed reporting of methodology. We address this problem and evaluate the current state of the art and recent methodological developments in actigraphy reporting with a special focus on infants and young children. Through a systematic literature search on PubMed (keywords: sleep, actigraphy, child *, preschool, children, infant), we identified 126 recent articles (published since 2012), which were classified and evaluated for reporting of actigraphy. Results show that all studies report on the number of days/nights the actigraph was worn. Reporting was good with respect to device model, placement and sleep diary, whereas reporting was worse for epoch length, algorithm, artefact identification, data loss and definition of variables. In the studies with infants only (n = 58), the majority of articles (62.1%) reported a recording of actigraphy that was continuous across 24 hr. Of these, 23 articles (63.9%) analysed the continuous 24-hr data and merely a fifth used actigraphy to quantify daytime sleep. In comparison with an evaluation in 2012, we observed small improvements in reporting of actigraphy methodology. We propose stricter adherence to standards in reporting methodology in order to streamline actigraphy research with infants and young children, to improve comparability and to facilitate big data ventures in the sleep community.

Signalling pathways contributing to learning and memory deficits in the Ts65Dn mouse model of Down syndrome

Down syndrome (DS) is a genetic trisomic disorder that produces life-long changes in physiology and cognition. Many of the changes in learning and memory seen in DS are reminiscent of disorders involving the hippocampal/entorhinal circuit. Mouse models of DS typically involve trisomy of murine chromosome 16 is homologous for many of the genes triplicated in human trisomy 21, and provide us with good models of changes in, and potential pharmacotherapy for, human DS. Recent careful dissection of the Ts65Dn mouse model of DS has revealed differences in key signalling pathways from the basal forebrain to the hippocampus and associated rhinal cortices, as well as changes in the microstructure of the hippocampus itself. In vivo behavioural and electrophysiological studies have shown that Ts65Dn animals have difficulties in spatial memory that mirror hippocampal deficits, and have changes in hippocampal electrophysiological phenomenology that may explain these differences, and align with expectations generated from in vitro exploration of this model. Finally, given the existing data, we will examine the possibility for pharmacotherapy for DS, and outline the work that remains to be done to fully understand this system.

A Review of Sleep Disturbances among Infants and Children with Neurodevelopmental Disorders

Sleep problems are common among children with neurodevelopmental disorders (NDDs). We review sleep disturbance in three major NDDs: autism spectrum disorder, Down syndrome, and fetal alcohol spectrum disorder (FASD). We review associations with functional impairment, discuss how patterns of sleep disturbance inform understanding of etiology, and theorize about mechanisms of impairment. Sleep disturbance is a transdiagnostic feature of NDDs. Caregivers report high rates of sleep problems, including difficulty falling or staying asleep. Polysomnography data reveal differences in sleep architecture and increased rates of sleep disorders. Sleep disturbance is associated with functional impairment and stress among families. Further research is needed to elucidate mechanisms of impairment and develop more effective interventions. Despite significant sleep disturbance in FASD, limited research is available.

Obstructive Sleep Apnoea Contributes to Executive Function Impairment in Young Children with Down Syndrome

OBJECTIVE/BACKGROUND

Children with Down syndrome (DS) commonly experience difficulties with executive function (EF). They are also vulnerable to obstructive sleep apnoea (OSA). OSA is associated with EF deficits in typically developing children. A recent study reported an association between OSA and cognitive deficits in 38 school-aged children with DS. We experimentally investigated EF behaviours in young children with DS, and their association with OSA.

PARTICIPANTS AND METHODS

Children with DS were recruited to take part in a larger study of OSA (N = 202). Parents of 80 children (50 male) aged 36 to 71 months (M = 56.90, SD = 10.19 months) completed the Behavior Rating Inventory of Executive Function - Preschool Version (BRIEF-P). Of these 80 children, 69 were also successfully studied overnight with domiciliary cardiorespiratory polygraphy to diagnose OSA.

RESULTS

Obstructive apnoea/hypopnoea index was in the normal range (0-1.49/h) for 28 children but indicated OSA (≥1.5/h) in 41 children. Consistent with previous research, we found a large effect for children experiencing particular weaknesses in working memory, planning and organising, whilst emotional control was a relative strength. OSA was associated with poorer working memory (β = .23, R2 = .05, p = .025), emotional control (β = .20, R2 = .04, p = .047) and shifting (β = .24, R2 = .06, p = .023).

CONCLUSIONS

Findings suggest that known EF difficulties in DS are already evident at this young age. Children with DS already have limited cognitive reserve and can ill afford additional EF deficit associated with OSA. OSA is amenable to treatment and should be actively treated in these children to promote optimal cognitive development.

Alterations of specific cortical GABAergic circuits underlie abnormal network activity in a mouse model of Down syndrome

Down syndrome (DS) results in various degrees of cognitive deficits. In DS mouse models, recovery of behavioral and neurophysiological deficits using GABA_AR antagonists led to hypothesize an excessive activity of inhibitory circuits in this condition. Nonetheless, whether over-inhibition is present in DS and whether this is due to specific alterations of distinct GABAergic circuits is unknown. In the prefrontal cortex of Ts65Dn mice (a well-established DS model), we found that the dendritic synaptic inhibitory loop formed by somatostatin-positive Martinotti cells (MCs) and pyramidal neurons (PNs) was strongly enhanced, with no alteration in their excitability. Conversely, perisomatic inhibition from parvalbumin-positive (PV) interneurons was unaltered, but PV cells of DS mice lost their classical fast-spiking phenotype and exhibited increased excitability. These microcircuit alterations resulted in reduced pyramidal-neuron firing and increased phase locking to cognitive-relevant network oscillations in vivo. These results define important synaptic and circuit mechanisms underlying cognitive dysfunctions in DS.

Down syndrome is a genetic disorder caused by the presence of a third copy of chromosome 21. Affected individuals show delayed growth, characteristic facial features, altered brain development; with mild to severe intellectual disability. The exact mechanisms underlying the intellectual disability in Down syndrome are unclear, although studies in mice have provided clues. Drugs that reduce the inhibitory activity in the brain improve cognition in a mouse model of Down syndrome. This suggests that excessive inhibitory activity may contribute to the cognitive impairments.

Many different neural circuits generate inhibitory activity in the brain. These circuits contain cells called interneurons. Sub-types of interneurons act via different mechanisms to reduce the activity of neurons. Identifying the interneurons that are affected in Down syndrome would thus improve our understanding of the brain basis of the disorder.

Zorrilla de San Martin et al. compared mice with Down syndrome to unaffected control mice. The results revealed an increased activity in two types of inhibitory brain circuits in Down syndrome. The first contains interneurons called Martinotti cells. These help the brain to combine inputs from different sources. The second contains interneurons called parvalbumin-positive basket cells. These help different areas of the brain to synchronize their activity, which in turn makes it easier for those areas to exchange information.

By mapping the changes in inhibitory circuits in Down syndrome, Zorrilla de San Martin et al. have provided new insights into the biological basis of the disorder. Future studies should examine whether targeting specific circuits with pharmacological treatments could ultimately help reduce the associated impairments.

Obstructive sleep apnea in children with down syndrome - Prevalence and evaluation of surgical treatment

INTRODUCTION

The prevalence of obstructive sleep apnea (OSA) in the pediatric population with Down syndrome (DS) is reported to be 45-76%. The criterion "gold" standard for diagnosing OSA is polysomnography (PSG). First-hand surgical treatment is adenotonsillectomy (ATE), and another option is adenopharyngoplasty (APP). The aims of this study were to determine the OSA prevalence among children with DS who had undergone PSG and to evaluate and compare the efficiency and results of ATE and APP treatments.

METHODS AND MATERIALS

Children <18 years old with DS who underwent PSG at Karolinska University Hospital were included in this retrospective cohort study. Medical records were examined for patient age, sex, medical comorbidity diagnoses, and OSA treatment, and the results from PSG and the quality of life questionnaire OSA-18 were registered. The prevalence and degree of OSA were calculated. Results from a nonsystematic subgroup that underwent postoperative PSG and the OSA-18 were compiled to evaluate surgical efficiency. Pre- and postoperative results from APP and ATE patients were compared.

RESULTS

In the study, 138 DS children were included. The OSA prevalence was 82.6%, and 39.9% had severe OSA, with a median (range) apnea hypopnea index (AHI) of 7.6 (0-104). Other comorbidity diagnoses were found for ear disease in 60%, circulatory disease in 51% and endocrine disease in 39% of patients. A nonsystematic subgroup of 33 patients underwent postoperative PSG, with a residual prevalence of moderate or severe OSA of 63.6%. Among the ATE and APP patients with pre- and postoperative PSG (n = 20), no difference between the groups was shown, but the values were significantly improved as a whole: the median AHI changed from 21.1 to 12.4 and the median OSA-18 rating changed from 54.0 to 35.0.

CONCLUSIONS

In this population of children with DS, the OSA prevalence was over 80%, wherefore continued screening and treatment are strongly supported. Uncertain surgical efficiency was indicated, and no significant difference in the results for ATE and APP was shown. When interpreting the results, it should be taken into consideration that the frequency of postoperative PSG was low and nonsystematic and that the groups were unequal and small.

Sleep is atypical across neurodevelopmental disorders in infants and toddlers: A cross-syndrome study

This cross-syndrome study focuses on sleep and its relationship with language development. Children with neurodevelopmental disorders present with language delay. Typical language development is constrained by numerous factors including sleep. Sleep is often disrupted in adolescents/adults with neurodevelopmental disorders. We therefore hypothesised that sleep may be disrupted, and correlate with language development, in infants/toddlers with neurodevelopmental disorders. To test our hypothesis, we obtained sleep and vocabulary size data from 75 infants/toddlers with one of three neurodevelopmental disorders (Down syndrome [DS], fragile X syndrome [FXS], Williams syndrome [WS]). Sleep was indeed disrupted in these children. It was also positively associated with receptive vocabulary size in the infants/toddlers with DS and WS (we could not test the relationship between sleep and language in FXS due to lack of power). We argue that disrupted sleep may be a common occurrence in very young children with neurodevelopmental disorders, and it may relate to their ability to acquire their first language.

Sleep problems and recall memory in children with Down syndrome and typically developing controls

BACKGROUND

Research conducted with typically developing (TD) infants and children generally indicates that better habitual sleep and sleep after learning are related to enhanced memory. Less is known, however, about associations between sleep and recall memory in children with Down syndrome (DS).

AIMS

The present study was conducted to determine whether parent-reported sleep problems were differentially associated with encoding, 1-month delayed recall memory, and forgetting over time in children with DS and those who were TD.

METHODS AND PROCEDURES

Ten children with DS (mean age = 33 months, 5 days) and 10 TD children (mean age = 21 months, 6 days) participated in a two-session study. At each session, recall memory was assessed using an elicited imitation paradigm. Immediate imitation was permitted at the first session as an index of encoding, and delayed recall was assessed 1 month later. In addition, parents provided demographic information and reported on child sleep problems.

OUTCOMES AND RESULTS

Although parents did not report more frequent sleep problems for children with DS relative to TD children, regression-based moderation analyses revealed that more frequent sleep problems were associated with increased forgetting of individual target actions and their order by children with DS. Evidence of moderation was not found when examining encoding or delayed recall.

CONCLUSIONS AND IMPLICATIONS

Although group differences were not found when considering parent-reported sleep problems, more frequent sleep problems were positively associated with increased forgetting by children with DS relative to those who were TD. Although future experimental work is needed to determine causality, these results suggest that improved sleep in children with DS might reduce forgetting, ultimately improving long-term recall memory.

Distribution and age of onset of psychopathological risk in a cohort of children with Down syndrome in developmental age

Background

Aim of the study is to intercept specific characteristics and psychiatric comorbidity in Down Syndrome (DS). The study describes the distribution and the age of specific aspects of behavioral phenotype in a sample of subjects with DS.

Methods

Psychopathological risk has been evaluated in a 97 DS patient cohort, aged 1 to 18 years, during regular follow-up neuropsychiatric visit and through administration of Child Behavior Checklist (CBCL); Childhood Autism Rating Scale (CARS-T) was assessed to verify the presence of autistic behaviors.

Results

The results show the presence of specific psychopathological risk factors in 90% of the sample. 7% of sample presents autistic features. The risk of psychopathology is independent of the degree of intellectual disability.

Conclusion

The high frequency of psychopathological risk factors indicates the need for accurate monitoring to intercept specific characteristics, such as in the case of comorbidity for autism. The search for specific psychopathological factors is a little explored aspect to date, as evidenced by the literature. Despite the studies available to date highlight the presence of psychopathological vulnerability in DS, so far there are only few reports that explore this issue systematically.

Cardiorespiratory sleep studies at home: experience in research and clinical cohorts

OBJECTIVE

To evaluate the success rates of home cardiorespiratory polygraphy in children under investigation for sleep-disordered breathing and parent perspectives on equipment use at home.

DESIGN

Prospective observational study.

SETTING

Sheffield, Evelina London and Southampton Children's Hospitals.

PATIENTS

Data are reported for 194 research participants with Down syndrome, aged 0.5-5.9 years across the three centres and 61 clinical patients aged 0.4-19.5 years from one centre, all of whom had home cardiorespiratory polygraphy including respiratory movements, nasal pressure flow, pulse oximetry, body position and motion.

MAIN OUTCOME MEASURES

Percentage of home cardiorespiratory studies successfully acquiring ≥4 hours of artefact-free data at the first attempt. Parental report of ease of use of equipment and preparedness to repeat home diagnostics in the future.

RESULTS

143/194 (74%; 95% CI 67% to 79%) of research participants and 50/61 (82%; 95% CI 71% to 90%) of clinical patients had successful home cardiorespiratory polygraphy at the first attempt. Some children required multiple attempts to achieve a successful study. Overall, this equated to 1.3 studies per research participant and 1.2 studies per clinical child. The median artefact-free sleep time for successful research studies was 515 min (range 261-673) and for clinical studies 442 min (range 291-583). 84% of research and 87% of clinical parents expressed willingness to repeat home cardiorespiratory polygraphy in the future. 67% of research parents found the equipment 'easy or okay' to use, while 64% of clinical parents reported it as 'easy' or 'very easy'.

CONCLUSIONS

Home cardiorespiratory polygraphy offers an acceptable approach to the assessment of sleep-disordered breathing in children.

Sleep problems in adults with Down syndrome and their family carers

BACKGROUND

Sleep disturbance is common and can have harmful psychological and physical effects. While sleep problems in children with Down syndrome (DS) have received a reasonable amount of attention, very little has been written about this topic in adults with DS.

METHOD

The present study consisted of an online survey completed by 100 family carers of adults with DS.

RESULTS

High rates of sleep problems of different types were reported in the adults with DS comparable to those found in children with DS in previous research. Significant associations were found between sleep problems and body mass index, excessive daytime sleepiness and a range of health and psychological problems. Low rates of treatments for sleep problems were reported. The majority of family caregivers felt their own sleep was affected.

CONCLUSIONS

Sleep problems in adults with DS are common and varied. Assessment and treatment of such problems are likely to improve quality of life.

Sleep and sleep disordered breathing in children with down syndrome: Effects on behaviour, neurocognition and the cardiovascular system

Down syndrome (DS), the most common human chromosomal malformation, has an estimated annual incidence of one in 1000 live births worldwide. Sleep problems are common in children with DS, reported by parents in up to 65% of school-aged children, significantly higher rates than in typically developing (TD) children. Problems include difficulty in sleep initiation and maintenance together with obstructive sleep apnoea (OSA) which affects up to over 90%, of DS children compared with 1-5% in the general paediatric population. Any sleep problem has the potential to exert significant negative effects on daytime behaviour, learning and quality of life in TD children and there is now a growing body of evidence that children with DS are similarly affected. In addition to adverse effects on daytime functioning, OSA has adverse effects on the cardiovascular system and this is a particularly significant issue given the high rates of hypertension and premature cardiac disease in people with DS. This review discusses the effects of sleep problems and OSA on daytime functioning and cardiovascular function in children with DS and evidence of the effectiveness of treatment in improving outcomes and quality of life for these children.

Influence of Schizophrenia-Associated Gene Egr3 on Sleep Behavior and Circadian Rhythms in Mice

Up to 80% of people meeting DSM-IV definitions for schizophrenia will exhibit difficulties with sleep, along with a breakdown in circadian entrainment and rhythmicity. The changes to the sleep and circadian systems in this population are thought to be interdependent, as evidenced by the frequent use of the combined term "sleep and circadian rhythm disruption" or "SCRD" to describe their occurrence. To understand links between sleep and circadian problems in the schizophrenia population, we analyzed the duration and rhythmicity of sleep behavior in mice lacking function of the immediate early gene early growth response 3 ( Egr3). EGR3 has been associated with schizophrenia risk in humans, and Egr3-deficient (-/-) mice display various features of schizophrenia that are responsive to antipsychotic treatment. While Egr3-/- mice slept less than their wildtype (WT) littermates, they showed no evidence of circadian disorganization; in fact, circadian rhythms of activity were more robust in these mice compared with WT, as measured by time series analysis and the relative amplitude index of Van Someren's suite of non-parametric circadian rhythm analyses. Differences in circadian robustness were maintained when the animals were transferred to several weeks of housing under constant darkness or constant light. Together, our results suggest that Egr3-/- mice retain control over the circadian timekeeping of sleep and wake, while showing impaired sleep. The findings are compatible with those from a surprising array of mouse models of schizophrenia and raise the possibility that SCRD may be 2 separate disorders in the schizophrenia population requiring different treatment strategies.

Melatonin Relations With Respiratory Quotient Weaken on Acute Exposure to High Altitude

High altitude (HA) exposure may affect human health and performance by involving the body timing system. Daily variations of melatonin may disrupt by HA exposure, thereby possibly affecting its relations with a metabolic parameter like the respiratory quotient (RQ). Sea level (SL) volunteers (7 women and 7 men, 21.0 ± 2.04 y) were examined for daily changes in salivary melatonin concentration (SMC). Sampling was successively done at SL (Antofagasta, Chile) and, on acute HA exposure, at nearby Caspana (3,270 m asl). Saliva was collected in special vials (Salimetrics Oral Swab, United Kingdom) at sunny noon (SMC_D) and in the absence of blue light at midnight (SMC_N). The samples were obtained after rinsing the mouth with tap water and were analyzed for SMC by immunoassay (ELISA kit; IBL International, Germany). RQ measurements (n = 12) were realized with a portable breath to breath metabolic system (Oxicon^TM Mobile, Germany), between 8:00 PM and 10:00 PM, once at either location. At SL, SMC_D, and SMC_N values (mean ± SD) were, respectively, 2.14 ± 1.30 and 11.6 ± 13.9 pg/ml (p < 0.05). Corresponding values at HA were 8.83 ± 12.6 and 13.7 ± 16.7 pg/ml (n.s.). RQ was 0.78 ± 0.07 and 0.89 ± 0.08, respectively, at SL and HA (p < 0.05). Differences between SMC_N and SMC_D (SMC_N-SMC_D) strongly correlate with the corresponding RQ values at SL (r = -0.74) and less tight at HA (r = -0.37). Similarly, mean daily SMC values (SMC) tightly correlate with RQ at SL (r = -0.79) and weaker at HA (r = -0.31). SMC_N-SMC_D, as well as, SMC values at SL, on the other hand, respectively, correlate with the corresponding values at HA (r = 0.71 and r = 0.85). Acute exposure to HA appears to loosen relations of SMC with RQ. A personal profile in daily SMC variation, on the other hand, tends to be conserved at HA.