Extreme enhancement or depletion of serotonin transporter function and serotonin availability in autism spectrum disorder

A variety of human and animal studies support the hypothesis that serotonin (5-hydroxytryptamine or 5-HT) system dysfunction is a contributing factor to the development of autism in some patients. However, many questions remain about how developmental manipulation of various components that influence 5-HT signaling (5-HT synthesis, transport, metabolism) persistently impair social behaviors. This review will summarize key aspects of central 5-HT function important for normal brain development, and review evidence implicating perinatal disruptions in 5-HT signaling in the pathophysiology of autism spectrum disorder. We discuss the importance, and relative dearth, of studies that explore the possible correlation to autism in the interactions between important intrinsic and extrinsic factors that may disrupt 5-HT homeostasis during development. In particular, we focus on exposure to 5-HT transport altering mechanisms such as selective serotonin-reuptake inhibitors or genetic polymorphisms in primary or auxiliary transporters of 5-HT, and how they relate to neurological stores of serotonin and its precursors. A deeper understanding of the many mechanisms by which 5-HT signaling can be disrupted, alone and in concert, may contribute to an improved understanding of the etiologies and heterogeneous nature of this disorder. We postulate that extreme bidirectional perturbations of these factors during development likely compound or synergize to facilitate enduring neurochemical changes resulting in insufficient or excessive 5-HT signaling, that could underlie the persistent behavioral characteristics of autism spectrum disorder.

Sleep disorders in children and adolescents

The scientific study of sleep and its disorders is essentially just a few decades old, but during that time impressive advances have been made in the biological knowledge of sleep. There has been recognition and treatment of a wide range of sleep disorders from which many people in all sections of the population suffer. The common adverse consequences of persistent sleep disturbance (at personal, educational, social and occupational levels) for members of the public at large have become clear (Dement & Mitler, 1993), as have the special risks of such problems to which certain groups are exposed – notably people with chronic psychiatric or physical disorders or learning disabilities.

Examining the Behavioural Sleep-Wake Rhythm in Adults with Autism Spectrum Disorder and No Comorbid Intellectual Disability

This study aimed to examine the behavioural sleep-wake rhythm in 36 adults with autism spectrum disorder (ASD) and to determine the prevalence of circadian sleep-wake rhythm disorders compared to age- and sex-matched controls. Participants completed an online questionnaire battery, a 14-day sleep-wake diary and 14-day actigraphy assessment. The results indicated that a higher proportion of adults with ASD met criteria for a circadian rhythm sleep-wake disorder compared to control adults. In particular, delayed sleep-wake phase disorder was particularly common in adults with ASD. Overall the findings suggest that individuals with ASD have sleep patterns that may be associated with circadian rhythm disturbance; however factors such as employment status and co-morbid anxiety and depression appear to influence their sleep patterns.

Assessment of Sleep in Children with Autism Spectrum Disorder

Sleep disturbances in children with autism spectrum disorder (ASD) are significantly more prevalent than found in typically developing (TD) children. Given the detrimental impact of poor sleep on cognitive, emotional, and behavioral functioning, it is imperative to screen and assess for sleep disturbances in this population. In this paper, we describe the screening and assessment process, as well as specific measures commonly used for assessing sleep in children with ASD. Advantages and limitations for use in children with ASD are discussed. While subjective measures, such as parent-report questionnaires and sleep diaries, are the most widely used, more objective measures such as actigraphy, polysomnography, and videosomnography provide additional valuable information for both diagnostic purposes and treatment planning. These objective measures, nonetheless, are limited by cost, availability, and feasibility of use with children with ASD. The current review provides an argument for the complementary uses of both subjective and objective measures of sleep specifically for use in children with ASD.

The multi-component nature of statistical learning

The central argument presented in this paper is that statistical learning (SL) is an ability comprised of multiple components that operate largely implicitly. Components relating to the stimulus encoding, retention and abstraction required for SL may include, but are not limited to, certain types of attention, processing speed and memory. It is likely that individuals vary in terms of the efficiency of these underlying components, and in patterns of connectivity among these components, and that SL tasks differ from one another in how they draw on certain underlying components more than others. This theoretical framework is of value because it can assist in gaining a clearer understanding of how SL is linked with individual differences in complex mental activities such as language processing. Variability in language processing across individuals is of central concern to researchers interested in child development, including those interested in neurodevelopmental disorders where language can be affected such as autism spectrum disorders (ASD). This paper discusses the link between SL and individual differences in language processing in the context of age-related changes in SL during infancy and childhood, and whether SL is affected in ASD. Viewing SL as a multi-component ability may help to explain divergent findings from previous empirical research in these areas and guide the design of future studies.This article is part of the themed issue 'New frontiers for statistical learning in the cognitive sciences'.

Risks and Protective Factors for Stress Self-Management in Parents of Children With Autism Spectrum Disorder: An Integrated Review of the Literature

PROBLEM

Stress in parents of children with autism spectrum disorder (ASD) has been reported to be very high. However, little is known about what risk and protective factors influence parental stress self-management in this population. Accordingly, this manuscript is a synthesis of the risk and protective factors that impact self-management of stress in these parents. The concepts in the individual and family self-management theory context domain were used as a framework to guide data collection and analysis.

ELIGIBILITY CRITERIA

Searches were conducted using CINAHL, MedLine and PsychInfo. Studies were included if they addressed context factors in parents of children with ASD and were written in English.

SAMPLE

Ninety-eight studies met review criteria.

RESULTS

This review highlighted risk factors to parental stress self-management within the context of condition-specific factors, physical and social environment, and individual and family. The most concerning of these findings is that parents struggle accessing a diagnosis and services for their child and are frustrated with health care providers' knowledge of ASD and lack of communication.

CONCLUSIONS

The risks parents experience as they care for their child with ASD far outweigh the protective factors for self-management of parental stress.

IMPLICATIONS

Nurses who are aware of these issues can make important changes to their practice and have a significant impact on parental stress self-management and the care of children with ASD.

Specific Medical Conditions Are Associated with Unique Behavioral Profiles in Autism Spectrum Disorders

Autism spectrum disorder (ASD) is a heterogeneous group of disorders which occurs with numerous medical conditions. In previous research, subtyping in ASD has been based mostly on cognitive ability and ASD symptom severity. The aim of the current study was to investigate whether specific medical conditions in ASD are associated with unique behavioral profiles. The medical conditions included in the study were macrocephaly, microcephaly, developmental regression, food selectivity, and sleep problems. The behavioral profile was composed of cognitive ability, adaptive skills, and autism severity, and was examined in each of the aforementioned medical conditions. The study population included 1224 participants, 1043 males and 181 females (M:F ratio = 5.8:1) with a mean age of 49.9 m (SD = 29.4) diagnosed with ASD using standardized tests. Groups with and without the specific medical conditions were compared on the behavioral measures. Developmental regression was present in 19% of the population and showed a more severe clinical presentation, with lower cognitive abilities, more severe ASD symptoms, and more impaired adaptive functioning. Microcephaly was observed in 6.3% of the population and was characterized by a lower cognitive ability and more impaired adaptive functioning in comparison to the normative head circumference (HC) group. Severe food selectivity was found in 9.8% and severe sleep problems in 5.1% of the ASD population. The food selectivity and sleep problem subgroups, both showed more severe autism symptoms only as described by the parents, but not per the professional assessment, and more impaired adaptive skills. Macrocephaly was observed in 7.9% of the ASD population and did not differ from the normative HC group in any of the examined behavioral measures. Based on these findings, two unique medical-behavioral subtypes in ASD that affect inherited traits of cognition and/or autism severity were suggested. The microcephaly phenotype occurred with more impaired cognition and the developmental regression phenotype with widespread, more severe impairments in cognition and autism severity. In contrast, severe food selectivity and sleep problems represent only comorbidities to ASD that affect functioning. Defining specific subgroups in ASD with a unique biological signature and specific behavioral phenotypes may help future genetic and neuroscience research.

The relationship between sleep and behavior in autism spectrum disorder (ASD): a review

Although there is evidence that significant sleep problems are common in children with autism spectrum disorder (ASD) and that poor sleep exacerbates problematic daytime behavior, such relationships have received very little attention in both research and clinical practice. Treatment guidelines to help manage challenging behaviors in ASD fail to mention sleep at all, or they present a very limited account. Moreover, limited attention is given to children with low-functioning autism, those individuals who often experience the most severe sleep disruption and behavioral problems. This paper describes the nature of sleep difficulties in ASD and highlights the complexities of sleep disruption in individuals with low-functioning autism. It is proposed that profiling ASD children based on the nature of their sleep disruption might help to understand symptom and behavioral profiles (or vice versa) and therefore lead to better-targeted interventions. This paper concludes with a discussion of the limitations of current knowledge and proposes areas that are important for future research. Treating disordered sleep in ASD has great potential to improve daytime behavior and family functioning in this vulnerable population.

Sleep patterns in children with and without autism spectrum disorders: developmental comparisons

The present study examined age-related changes in the sleep of children with autism spectrum disorders (ASD) compared to age-related changes in the sleep of typically developing (TD) children. Participants were 108 mothers of children with ASD and 108 mothers of TD children. Participants completed a questionnaire on children's overall sleep quality that also tapped specific sleep-domains (i.e., bedtime resistance, sleep onset delay, sleep duration, sleep anxiety, night wakings, parasomnias, disordered breathing, daytime sleepiness). Results confirm significantly poorer sleep quantity and quality in children with ASD, particularly children age 6-9 years. Unlike TD children, the sleep problems of children with ASD were unlikely to diminish with age. Our findings suggest that it is important to exam specific domains of sleep as well as overall sleep patterns. Finding of significant age-related interactions suggests that the practice of combining children from wide age-ranges into a single category obfuscates potentially important developmental differences.

Behavioral interventions for sleep problems in children with autism spectrum disorders: current findings and future directions

OBJECTIVE

To examine behavioral interventions for sleep problems in children with autism spectrum disorders (ASD).

METHODS

A systematic review evaluating all published studies examining the effectiveness of behavioral treatment of sleep problems in children with ASD is presented.

RESULTS

Based on the Chambless criteria for treatment efficacy, both standard extinction and scheduled awakenings met criteria for possibly efficacious interventions for sleep problems in children with ASD. Some positive outcomes have been reported, but there has not been enough research examining graduated extinction, faded bedtime, stimulus fading and chronotherapy to make any firm conclusions regarding treatment efficacy for children with ASD.

CONCLUSIONS

Although more rigorous research is required in order for any sleep interventions for children with ASD to be considered probably efficacious or well-established, the current literature should be used to guide clinical decisions and direct research questions.

An investigation of sleep characteristics, EEG abnormalities and epilepsy in developmentally regressed and non-regressed children with autism

This study investigated sleep of children with autism and developmental regression and the possible relationship with epilepsy and epileptiform abnormalities. Participants were 104 children with autism (70 non-regressed, 34 regressed) and 162 typically developing children (TD). Results suggested that the regressed group had higher incidence of circadian rhythm disorders than non-regressed children. The regressed group showed higher Children's Sleep Habits Questionnaire Bedtime Resistance, Sleep Onset Delay, Sleep Duration and Night-Wakings scores. Epilepsy and frequent epileptiform EEG abnormalities were more frequent in regressed children. Past sleep disorders and a history of developmental regression were significantly associated with sleep disorders. This study is an initial step in better understanding sleep problems in regressed children with autism, further studies are necessary to better investigate these aspects.

A comparative study of circadian rhythm functioning and sleep in people with Asperger syndrome

The circadian rhythm functioning and sleep patterns of 10 adults with Asperger syndrome were investigated using actigraphy. When compared with data from neurotypical adults, both statistical and clinically significant differences were found between the two groups, with the adults with Asperger syndrome showing marked abnormalities in both the quantity and the quality of sleep recorded. Examination of the actigraphic data indicated low sleep efficiency and high fragmentation as being characteristic of the sleep of participants with Asperger syndrome. These individuals also showed lower-amplitude circadian rhythms that were less strongly linked to environmental synchronizers, but no evidence of significant desynchronization of circadian rhythm. Possible mechanisms for these abnormalities and implications for clinical practice are discussed.

Sleep disturbances and correlates of children with autism spectrum disorders

This study examined sleep patterns, sleep problems, and their correlates in children with autism spectrum disorders (ASD). Subjects consisted of 167 ASD children, including 108 with autistic disorder, 27 with Asperger's syndrome, and 32 with other diagnoses of ASD. Mean age was 8.8 years (SD = 4.2), 86% were boys. Parents completed a self-administered child sleep questionnaire. Results showed that average night sleep duration was 8.9 h (SD = 1.8), 16% of children shared a bed with parent. About 86% of children had at least one sleep problem almost every day, including 54% with bedtime resistance, 56% with insomnia, 53% with parasomnias, 25% with sleep disordered breathing, 45% with morning rise problems, and 31% with daytime sleepiness. Multivariate logistic regression analyses indicated that younger age, hypersensitivity, co-sleeping, epilepsy, attention-deficit/hyperactivity disorder (ADHD), asthma, bedtime ritual, medication use, and family history of sleep problems were related to sleep problems. Comorbid epilepsy, insomnia, and parasomnias were associated with increased risk for daytime sleepiness. Results suggest that both dyssomnias and parasomnias are very prevalent in children with ASD. Although multiple child and family factors are associated with sleep problems, other comorbid disorders of autism may play a major role.

Objective investigation of the sleep-wake cycle in adults with intellectual disabilities and autistic spectrum disorders

BACKGROUND

Disturbances in circadian rhythm functioning, as manifest in abnormal sleep-wake cycles, have been postulated to be present in people with autistic spectrum disorders (ASDs). To date, research into the sleep-wake cycle in people with ASDs has been primarily dependant on third-party data collection.

METHOD

The utilization of non-invasive objective recording technologies such as actigraphy permits investigation of both sleep and circadian rhythm functioning in people with ASDs, together with the collection of data on daytime activity.

RESULTS

Data were collected from 31 participants with intellectual disabilities living in supported community-based residential provision aged between 20 and 58 years, of whom 14 had an ASD. Analysis indicated that there were no significant differences in sleep patterns and circadian rhythm function between those participants with an ASD and those without.

CONCLUSIONS

The mean scores of the participants as a whole indicated abnormalities in the two key circadian rhythm parameters of interdaily stability and intradaily variability. The implications of these findings for both clinical practice and theory are discussed.

Atypical sleep architecture and the autism phenotype

A growing body of evidence indicates that people with autism frequently experience sleep disorders and exhibit atypical sleep architecture. In order to establish whether sleep disorders truly belong to the autism spectrum disorder (ASD) phenotype, we conducted a subjective and objective study of sleep in a group of high-functioning adults with ASD but without sleep complaints, psychiatric disorders or neurological comorbidity. We compared the subjective data of 27 ASD participants with those of 78 healthy controls matched for chronological age and gender. Subjective measures of sleep in the clinical group were compatible with insomnia and/or a tolerable phase advance of the sleep-wake cycle. Subjective data were confirmed by objective laboratory sleep recordings in a subset of 16 patients and 16 controls. Persons with autism presented with a longer sleep latency (P < 0.04), more frequent nocturnal awakenings (P < 0.03), lower sleep efficiency (P < 0.03), increased duration of stage 1 sleep (P < 0.02), decreased non-REM sleep (stages 2 + 3 + 4, P < 0.04) and slow-wave sleep (stages 3 + 4, P < 0.05), fewer stage 2 EEG sleep spindles (P < 0.004), and a lower number of rapid eye movements during REM sleep (P < 0.006) than did control participants. On clinical scales, the scores of persons with ASD on the Beck Depression Inventory were similar to those of persons without, but their trait anxiety scores on the Spielberger Anxiety Scale were higher (P < 0.02). The state anxiety scores of the Spielberger scale and cortisol levels were the same in the two groups. Objective total sleep time correlated negatively with the Social (-0.52, P < 0.05) and Communication (-0.54, P < 0.02) scales of the Autism Diagnostic Interview-Revised. The sleep of clinical subgroups (10 with high-functioning autism, six with Asperger syndrome) did not differ, except for the presence of fewer EEG sleep spindles in the Asperger syndrome subgroup (P < 0.05). In conclusion, these findings indicate that atypicalities of sleep constitute a salient feature of the adult ASD phenotype and this should be further investigated in younger patients. Moreover, the results are consistent with an atypical organization of neural networks subserving the macro- and microstructure of sleep in ASD. We are furthering this research with quantified analysis of sleep EEG.

Sleep patterns and sleep disorders in children with autistic spectrum disorders: insights using parent report and actigraphy

The present study sought to describe the profile of sleep disturbance reported in children with autistic spectrum disorders (ASDs) and to document any sleep disorders underlying reports of sleeplessness. Sixty-nine children aged 5 to 16 years (mean 9 years 4 months, SD 2 years 7 months; 14 females) with an ASD were assessed by detailed sleep histories taken from parents, the Simonds and Parraga Sleep Questionnaire, a 2-week sleep diary, and actigraphs worn by the child for five nights. Parent-reported sleeplessness featured prominently (64%). Sleep disorders underlying the sleeplessness were most commonly behavioural (i.e. to do with inappropriate sleep-related behaviours), although sleep-wake cycle disorders and anxiety-related problems were also seen. In addition, the sleeplessness patterns of a large minority of children could not be classified by conventional diagnostic criteria. Sleep patterns measured objectively did not differ between those children with or without reported sleeplessness, but the sleep quality of all children seemed to be compromised compared with normal values.

Sleep in children with psychiatric disorders

Although the exact nature of sleep disturbances present in children with psychiatric disorders has not been studied extensively, it is apparent that children with significant emotional and behavioral problems are more likely to experience sleep difficulties. Children with sleep-related issues that are limited to bedtime can be managed effectively with specific cognitive-behavioral interventions. Children with more pervasive anxiety (eg, PTSD or OCD, mood disorders such as major depression or bipolar disorder, or neurodevelopmental disabilities such as autism) require a more exhaustive evaluation, and most of them also need sleep problems to be managed by sleep professionals using combinations of psychotherapeutic and pharmacologic approaches.

Autism: a novel form of mercury poisoning

Autism is a syndrome characterized by impairments in social relatedness and communication, repetitive behaviors, abnormal movements, and sensory dysfunction. Recent epidemiological studies suggest that autism may affect 1 in 150 US children. Exposure to mercury can cause immune, sensory, neurological, motor, and behavioral dysfunctions similar to traits defining or associated with autism, and the similarities extend to neuroanatomy, neurotransmitters, and biochemistry. Thimerosal, a preservative added to many vaccines, has become a major source of mercury in children who, within their first two years, may have received a quantity of mercury that exceeds safety guidelines. A review of medical literature and US government data suggests that: (i) many cases of idiopathic autism are induced by early mercury exposure from thimerosal; (ii) this type of autism represents an unrecognized mercurial syndrome; and (iii) genetic and non-genetic factors establish a predisposition whereby thimerosal's adverse effects occur only in some children.

A laboratory study of sleep in Asperger's syndrome

Asperger's syndrome (AS) is a pervasive developmental disorder that may fall along the autistic spectrum. We compared the sleep of eight patients with AS with that of participants matched for age and gender. Patients with AS showed decreased sleep time in the first two-thirds of the night, increased number of shifts into REM sleep from a waking epoch, and all but one patient showed signs of REM sleep disruption. EEG sleep spindles were significantly decreased while K complexes and REM sleep rapid eye movements were normal. Three patients with AS, but none of the comparison participants, showed a pathological index of periodic leg movements in sleep. These observations show that sleep disorders are associated with AS and suggest that defective sleep control systems may be associated with the clinical picture of AS.