Types Of Intellectual Disability Research Articles

Tuberous sclerosis complex in adulthood: focus on epilepsy prognosis

ObjectiveTypically diagnosed in early childhood or adolescence, TSC is a chronic, multisystemic disorder with age-dependent manifestations posing a challenge for transition and for specific surveillance throughout the lifetime. Data on the clinical features and severity of TSC in adults and on the prognosis of epilepsy are scarce. We analyzed the clinical and genetic features of a cohort of adult patients with TSC, to identify the prognostic predictors of seizure remission after a long follow-up. MethodWe conducted a retrospective analysis of patients diagnosed with TSC according to the updated international diagnostic criteria. Pearson’s chi-square or Fisher’s exact test and Mann Whitney U test were used to compare variables among the Remission (R) and Non-Remission (NR) group. Univariate and multivariate logistic regression analyses were performed. ResultsWe selected 43 patients with TSC and neurological involvement in terms of epilepsy and/or brain lesions, attending the Epilepsy Center of our Institute: of them, 16 (37.2%) were transitioning from the pediatric care and 6 (13.9%) were referred by other specialists. Multiorgan involvement includes cutaneous (86.0%), nephrological (70.7%), hepatic (40.0%), ocular (34.3%), pneumological (28.6%) and cardiac (26.3%) manifestations.Thirty-nine patients (90.7 %) had epilepsy. The mean age at seizure onset was 4 ± 7.3 years: most patients (29, 76.3 %) presented with focal seizures or spasms by age 3 years; only 2 (5.3 %) had seizure onset in adulthood. Twenty-seven patients (69.2 %) experienced multiple seizure types overtime, 23 (59.0 %) had intellectual disability (ID). At last assessment, 14 (35.9 %) were seizure free (R group) and 25 (64.1 %) had drug-resistant seizures (NR group). At logistic regression univariate analysis, ID (OR 7.9, 95 % CI 1.8––34.7), multiple seizure types lifelong (OR 13.2, 95 % CI 2.6– 67.2), spasms/tonic seizures at presentation (OR 6.5, 95 % CI 1.2––35.2), a higher seizure frequency at onset (OR 5.4, 95 % CI 1.2––24.3), abnormal neurological examination (OR 9.8, 95 % CI 1.1––90.6) and pathogenic variants in TSC2 (OR 5.4, 95 % CI 1.2––24.5) were significantly associated with non-remission. In the multivariate analysis, both ID and multiple seizure types lifelong were confirmed as independent predictors of poor seizure outcome. ConclusionsIn our cohort of adult patients with TSC, epilepsy remains one of the main neurological challenges with only 5.3% of cases manifesting in adulthood. Approximately 64% of these patients failed to achieve seizure remission. ID and multiple seizure types were the main predictors of poor outcome. Nephrological manifestations require continuous specific follow-up in adults.

A novel variant of C12orf4 linked to autosomal recessive intellectual disability type 66 with phenotype expansion.

Intellectual disability (ID) is a hallmark of many rare disorders that are highly heterogeneous and complex. A large number of specific genes are involved in development of this heterogeneity, and each of these genes is only found in a small number of patients. This weakens the definition of the predominant genotype and the phenotypic characteristics associated with that gene. Autosomal recessive ID type 66 (OMIM #618221) is one of these very rare diseases created by defects in the C12orf4 gene. The present study included two patients from an Iranian family with initial diagnosis of non-syndromic ID, aiming to identify the possible genetic cause(s), and whole-exome sequencing (WES) was performed for the proband. The obtained variant was confirmed by Sanger sequencing and co-segregated in the family. The patients carried a novel pathogenic splicing variant called c.1441-1G>A in exon 12 of the C12orf4 gene (NM_001304811). They predominantly manifested ID, behavioral problems, speech impairment and dysmorphic facial features, some of which had not been reported in previous studies. A novel pathogenic splicing variant was identified named c.1441-1G>A in the C12orf4 gene. To date, only seven families have been reported with defects in this gene. Previous studies have not highlighted the exact clinical manifestations of these patients; thus, the present study could contribute to a better delineation of the genotype-phenotype correlation and interpretation of very rare variants of the gene.

Task-Related Brain Connectivity Activation Functional Magnetic Resonance Imaging in Intellectual Disability Population: A Meta-Analytic Study.

Introduction: Neuroimaging studies of intellectual disability (ID) have been published over the last three decades, but the findings are often inconsistent, and therefore, the neural correlates of ID remain elusive. This article aims to study the different publications in task-functional magnetic resonance imaging (fMRI) and different ID populations to make a qualitative and quantitative analysis on this field. Methods: After duplicates were removed, only 10 studies matching our inclusion criteria were incorporated. Moreover, a quality assessment of the included studies was done. Qualitative results of the different articles were analyzed, separated by type of task and type of ID. Seed-based d mapping (SDM) software was used. Results: The right temporal gyrus was more activated in control subjects than in ID. Concretely, the right temporal gyrus is implicated in many cognitive domains as semantic memory processing and language. Moreover, it can be highly influenced by the type of task used in every study. Heterogeneity was not detected. A jackknife sensitivity analysis was also estimated to improve the analysis reliability, and both results were confirmed. Conclusions: More task-fMRI studies on ID must be published to add larger samples to address the pathophysiological questions more directly. Impact statement In this article, the state-of-the-art in the field of functional magnetic resonance imaging (fMRI) and intellectual disability (ID) is reviewed. Moreover, we perform a meta-analysis of every article's results to summarize the principal outcomes in the field. It is very relevant because it has become the first meta-analytic study to overcome all the principal studies published in fMRI and ID to find the principal neurological substrates while the subjects are performing a task.

Overweight/obesity and chronic health conditions in older people with intellectual disability in Ireland.

This study examines overweight/obesity and chronic health conditions (CHCs) in older people with intellectual disability (ID). Data for this cross-sectional observational study emanated from Wave 2 of the Intellectual Disability Supplement to the Irish Longitudinal Study on Ageing, a longitudinal study assessing the health and well-being of older Irish adults with ID aged ≥40years across all levels of ID. Participation involves an interview process and collation of objective health measures. In this study, body mass index (BMI) (n=572), used as a measure of weight status, was examined with clustered doctor's diagnosed CHCs. Descriptive analysis was conducted where counts (n) and proportions (%) were used to summarise the variables univariately, while cross-tabulations were used for bivariate summary into counts and proportions. With overweight/obesity prevalence established and patterns described using logistical regression, Pearson's chi-squared test was used to test for significant associations. Overweight/obesity identified in 69% of participants occurred with greater frequency in women (72%). A higher percentage of participants aged <50years (72.5%) were overweight/obese than those aged 50-64 (70%) and 65+ (61.4%). Level of ID and residence type were significantly associated with weight status (P<0.001), with overweight/obesity more prevalent in mild (85.7%) than moderate (72%) or severe/profound ID (51.4%). Of those who lived independently/with family, 78.4% were overweight/obese, as were 74% living in a community group home (P<0.001). Almost all overweight/obese participants' waist measurements were in the substantially increased risk of metabolic disease waist measurement category (92%, P<0.001). Logistical regression used to model CHCs on BMI showed significant association between BMI and gastrointestinal tract [odds ratio (OR)=0.57, P<0.008, 95% confidence interval (CI)=(0.37; 0.86)], respiratory condition [OR=8.95, P<0.004, 95% CI=(2.57; 56.72)] and musculoskeletal disorders [OR=0.40, P<0.001, 95% CI=(0.25; 0.63)]. The findings illustrate the strong cross-sectional association between overweight/obesity and CHCs. These findings suggest a need to prioritise weight status as a health risk to people with ID as they age.

Management of Keratoconus in Down Syndrome and Other Intellectual Disability.

The purpose of this study was to assess an intellectual disability (ID) cohort with keratoconus (KC) regarding ophthalmic (visual acuity and corneal tomography) and systemic characteristics and to describe an appropriate clinical algorithm for investigation and management of KC in this setting. This was the retrospective cohort study of patients with ID (Down syndrome, autism, and other) in the cornea department of a tertiary referral ophthalmic hospital in Dublin, Ireland. Retrospective chart review was conducted on people with ID undergoing examination under anesthesia or crosslinking under general anesthetic. Key outcome data included corneal examination findings, corneal tomography, visual acuity, and examination findings (eg, type of ID, general anesthetic, and cardiac status). Mean age of the 24 patients was 31.9 years (66.7% male). ID type was Down syndrome (66.7%), autism (25%), and other (8.3%). KC was diagnosed in 98% of eyes, with 45.8% having untreatable advanced disease (57.1% of these bilateral), 39.6% amenable to corneal collagen crosslinking (35.7% of these bilateral), and 6.3% having corneal transplantation. Congenital heart defects were present in 37.5% of the Down syndrome group. There were no serious ocular or systemic adverse events. KC is strikingly prevalent in the ID population. Ireland has the highest rate of Down syndrome in Europe (26.3:10,000 live births). This group is rarely suitable for corneal transplantation, and corneal collagen crosslinking is an effective intervention to prevent progression to advanced KC in this already socially restricted group. We propose an algorithm for investigation/treatment and also recommend uniform pediatric KC screening/treatment in ID populations.

A bio-behavioral intervention combining task analysis with skill-based training to train toothbrushing among children with intellectual disability.

Individuals with intellectual disability (ID) have special health care needs. Teaching self-care behaviors like toothbrushing helps reduce their dependence on adult caregivers. We present a bio-behavioral intervention combining task analysis with skill-based teaching of toothbrushing behavior aimed to promote autonomy in children with various types of ID. One hundred twenty children with ID enrolled at a special school in the State were included in the study. After baseline measurements using task analysis, four methods were used to train the children - instruction, three-phase modeling, physical guidance, and descriptive praise. The caregiver was trained and given instructional videos for reinforcement. After 4weeks, the children were asked to brush their teeth and performance was evaluated. There was increased independence in the performance of toothbrushing behavior, the mild and moderate ID groups showing the most improvement. Steps like oral manipulation of the toothbrush showed the greatest improvement in these groups. The severe ID group showed improvement in certain skills, while requiring assistance for others that demanded dexterity. This intervention can be implemented by special schools and special care dentistry centers to foster autonomy in oral self-care skills in the mild and moderate ID children, and complemented with other methods for severe ID children.

A novel homozygous variant in the TRAPPC9 gene causing intellectual disability and autism Spectrum disorder

Intellectual disability (ID) is a prevalent and genetically and clinically heterogeneous neurodevelopmental disorder. ID may be a sole phenotype of the condition (nonsyndromic ID) or it may present in conjunction with other clinical manifestations (syndromic ID). TRAPPC9 is one of several genes found to be involved in both types of ID and autism. Using whole-exome sequencing, we investigated the genetic basis of syndromic ID in a brother and sister from a consanguineous Egyptian family and detected a homozygous transition (c.2635C > T) in exon 16 of the TRAPPC9 gene. For the most part, this novel variant likely results in nonsense-mediated mRNA decay, while the residual mRNA might be translated into a truncated protein product (p.(Gln879*)) lacking an important functional domain. The phenotype of our patients included moderate ID, autistic behavior, microcephaly, characteristic facial appearance, EEG abnormalities, hypoplastic corpus callosum, and white matter hypomyelination. Importantly, autistic behavior, facial dysmorphism, and abnormal EEG patterns have been described or investigated only rarely in other reported individuals with biallelic TRAPPC9 changes. Thus, our work highlights the importance of these clinical features in TRAPPC9-related ID. Furthermore, a comprehensive description of clinical features associated with novel TRAPPC9 changes may facilitate genotype-phenotype correlation and offer some clues as to why certain pathogenic variants in theTRAPPC9 gene lead to solely brain-related phenotypes in some patients and syndromic phenotypes in others. Carrier detection molecular testing also was done for nine family members (two unaffected siblings, both parents, three uncles, and both grandmothers).

Sex and genes, part 2: A biopsychosocial approach to assess and treat challenging sexual behavior in persons with intellectual disabilities including fragile X syndrome and 22q11.2 deletion syndrome.

Individuals with intellectual disabilities (IDs) - and specifically those with genetic disorders - are more prone to medical and psychological challenges that affect their sexual development, experiences, and fertility. In this review paper we first provide an overview of the biopsychosocial (BPS) model and then explain how the model can guide and improve the assessment and treatment of challenging sexual behaviors by persons with IDs. We discuss two genetic conditions - fragile X syndrome and 22q11.2 deletion syndrome - in case studies, showing how the BPS model can be used to assess and treat the sexual problems of individuals with various types of ID. We conclude with BPS-formulated treatment considerations in three key domains: biomedical treatment (e.g., medication side effects; stopping or changing medications), psychological treatment (e.g., providing psychological therapies), and socio-environmental interventions (e.g., providing socio-sexual education and staff training). Together, these treatment interventions can aid clinicians to prevent and/or treat problematic sexual behaviors of people with IDs.

Analysis of electroencephalogram-derived indexes for anesthetic depth monitoring in pediatric patients with intellectual disability undergoing dental surgery.

BackgroundPatients with intellectual disability (ID) often require general anesthesia during oral procedures. Anesthetic depth monitoring in these patients can be difficult due to their already altered mental state prior to anesthesia. In this study, the utility of electroencephalographic indexes to reflect anesthetic depth was evaluated in pediatric patients with ID.MethodsSeventeen patients (mean age, 9.6 ± 2.9 years) scheduled for dental procedures were enrolled in this study. After anesthesia induction with propofol or sevoflurane, a bilateral sensor was placed on the patient's forehead and the bispectral index (BIS) was recorded. Anesthesia was maintained with sevoflurane, which was adjusted according to the clinical signs by an anesthesiologist blinded to the BIS value. The index performance was accessed by correlation (with the end-tidal sevoflurane [EtSevo] concentration) and prediction probability (with a clinical scale of anesthesia). The asymmetry of the electroencephalogram between the left and right sides was also analyzed.ResultsThe BIS had good correlation and prediction probabilities (above 0.5) in the majority of patients; however, BIS was not correlated with EtSevo or the clinical scale of anesthesia in patients with Lennox-Gastaut, West syndrome, cerebral palsy, and epilepsy. BIS showed better correlations than SEF95 and TP. No significant differences were observed between the left- and right-side indexes.ConclusionBIS may be able to reflect sevoflurane anesthetic depth in patients with some types of ID; however, more research is required to better define the neurological conditions and/or degrees of disability that may allow anesthesiologists to use the BIS.

Genotyping and clinical characteristics screening of children with intellectual disability in Western India

Background: The RhoGTPases (ARHGEF6, OPHN1 and PAK3) are key signaling proteins, and can inter-relate extracellular and intracellular signals to sort out changes in the actin cytoskeleton of neuronal network connectivity. IL1RAPL2 is a member of Interleukin 1 receptor family that is expressed at high level in post-natal brain structures involved in the hippocampal memory system. The mutations of these genes have been reported to cause intellectual disability (ID). Therefore, this study is conducted to scrutinize distinctive distributions of genomic variations on West Indian population. Subjects and Methods: The genotyping for determination of SNPs associated with X-linked genes (rs35747426 in ARHGEF6, rs121434612 in PAK3, rs199985543 in OPHN1 and rs9887672 in IL1RAPL2) was performed in phenotypically screened 116 intellectually disabled and 100 healthy children by PCRRFLP method. Results: It has identified that allelic frequencies for rs199985543 and rs9887672 are seen progressively present in the disease group, indicating a significant level of association with ID in Gujarat population. The multifactor dimensionality reduction (MDR), SNP-SNP genotype models are resulted with a relationship of ID if there should be an occurrence of the OPHN1 and IL1RAPL2 gene variants. Additionally, rs199985543 was analyzed for OPHN1 protein structure and stability prediction, which results damaging effect to the protein. Surprisingly, no variation was found for rs35747426 ARHGEF6 and rs121434612 PAK3 polymorphisms in the present study population. Conclusion: This phenotype-genotype relationship has a solid and measurable connection according to the carrier genotypes of the variations and different types of ID, that confirm the mutation in OPHN1 and IL1RAPL2 genes permit serious attention for disease risk.

Perampanel in the general population and in people with intellectual disability: Differing responses

PurposeThere is a shortfall of suitably powered studies to provide evidence for safe prescribing of AEDs to people with Intellectual Disability (ID). We report clinically useful information on differences in response to Perampanel (PER) adjunctive treatment for refractory epilepsy between ID sub-groups and general population from the UK Ep-ID Research Register. MethodPooled retrospective case notes data of consented people with epilepsy (PWE) prescribed PER from 6 UK centres was classified as per WHO guidance into groups of moderate -profound ID, mild ID and General population. Demographics, concomitant AEDs, starting and maximum dosage, exposure length, adverse effects, dropout rates, seizure type and frequency were collected. Group differences were reported as odds ratios estimated from univariable logistic regression models. ResultsOf the 144 PWE (General population 71, Mild ID 48, Moderate to profound ID 48) examined the association between withdrawal and ID type was marginally statistically significant (p=0.07). Moderate to profound ID PWE were less likely to come off PER compared to mild ID (OR=0.19, CI=0.04–0.92, p=0.04). Differences in mental health side effects by groups was marginally statistically significant (p=0.06). Over 50% seizure improvement was seen in 11% of General population, 24% mild ID and 26% Moderate to profound ID. ConclusionsPER seems safe in PWE with ID. It is better tolerated by PWE with Moderate to profound ID than PWE with higher functioning. Caution is advised when history of mental health problems is present. The standardised approach of the Ep-ID register UK used confirms that responses to AEDs by different ID groups vary between themselves and General population.

Rearing styles and psychopathology in children and adolescents with intellectual disability from Chile and Spain

The aims of our study were: a) to evaluate how parenting styles vary according to the presence of intellectual disability (ID) and between two cultures – Chile and Spain –; and to value their association with psychopathology. Participants were 236 children and adolescents aged 8-14, who were classified in the following three groups according to the type of ID: with Down syndrome (DS), idiopathic intellectual disability (IID) or without disability. Parents answered a questionnaire on perceived rearing style and psychopathology. Our results showed that in Chile DS group perceived less overprotection. Clinical scores were associated with overprotection, rejection and the presence of ID. Moreover, the Chilean participants reported more depression and somatisation than the Spanish participants. We expect our findings will contribute to the prevention and intervention of unfavourable rearing styles and psychopathology in ID.

Profile of Social, Environmental and Biological Correlates in Intellectual Disability in A Resource-Poor Setting in India.

Background:Intellectual disability (ID) is a major public health issue in India. Social, environmental and biological factors all contribute to the nation's high rate of ID.Objective:We aimed to investigate the distribution, differences and the association of social, environmental and biological factors with different types of ID in a mixed (tribal and non-tribal) population in India.Materials and Methods:Secondary data was collected during a community-based rehabilitation project and analyzed with descriptive statistics: Frequency, percentage and χ2.Results:Poverty, low levels of parental education and a family history of epilepsy and ID were all associated in both tribal and non-tribal populations (P < 0.05).Conclusion:The outcome of this study may be helpful in planning public health initiatives that aim to reduce the burden of ID in mixed populations.

Exome sequencing identifies three novel candidate genes implicated in intellectual disability.

Intellectual disability (ID) is a major health problem mostly with an unknown etiology. Recently exome sequencing of individuals with ID identified novel genes implicated in the disease. Therefore the purpose of the present study was to identify the genetic cause of ID in one syndromic and two non-syndromic Pakistani families. Whole exome of three ID probands was sequenced. Missense variations in two plausible novel genes implicated in autosomal recessive ID were identified: lysine (K)-specific methyltransferase 2B (KMT2B), zinc finger protein 589 (ZNF589), as well as hedgehog acyltransferase (HHAT) with a de novo mutation with autosomal dominant mode of inheritance. The KMT2B recessive variant is the first report of recessive Kleefstra syndrome-like phenotype. Identification of plausible causative mutations for two recessive and a dominant type of ID, in genes not previously implicated in disease, underscores the large genetic heterogeneity of ID. These results also support the viewpoint that large number of ID genes converge on limited number of common networks i.e. ZNF589 belongs to KRAB-domain zinc-finger proteins previously implicated in ID, HHAT is predicted to affect sonic hedgehog, which is involved in several disorders with ID, KMT2B associated with syndromic ID fits the epigenetic module underlying the Kleefstra syndromic spectrum. The association of these novel genes in three different Pakistani ID families highlights the importance of screening these genes in more families with similar phenotypes from different populations to confirm the involvement of these genes in pathogenesis of ID.

Measuring Body Composition in Individuals with Intellectual Disability: A Scoping Review

Background. Research shows obesity to be more prevalent amongst individuals with intellectual disability (ID) making correct measurement of body composition crucial. This study reviewed the validity and reliability of methods used for assessing body composition in individuals with ID. Methods. Authors conducted electronic searches through PubMed (1990 to present) and PsycINFO (1990 to present) and assessed relevant articles independently based on scoping review guidelines. Reviewers included primary research related to the validity and reliability of body composition measures on individuals with ID. Results. Searches identified six articles assessing body composition methods used on individuals with ID including body mass index (BMI), skinfold thickness, bioelectrical impedance analysis (BIA), waist circumference, tibia length, and anthropometric girth measurements. BMI and waist circumference appear suitable measures but skinfold thickness measurements may not be advisable due to participants' noncompliance resulting in a lack of precision and inaccurate results. Conclusions. The current literature contains too few well-conducted studies to determine the precision and validity of body composition measures on individuals with ID. There may be a need to devise further regression equations that apply to individuals with specific types of ID in order to increase the reliability and validity of body composition measurements.

Haploinsufficiency of ARID1B, a Member of the SWI/SNF-A Chromatin-Remodeling Complex, Is a Frequent Cause of Intellectual Disability

Intellectual disability (ID) is a clinically and genetically heterogeneous common condition that remains etiologically unresolved in the majority of cases. Although several hundred diseased genes have been identified in X-linked, autosomal-recessive, or syndromic types of ID, the establishment of an etiological basis remains a difficult task in unspecific, sporadic cases. Just recently, de novo mutations in SYNGAP1, STXBP1, MEF2C, and GRIN2B were reported as relatively common causes of ID in such individuals. On the basis of a patient with severe ID and a 2.5 Mb microdeletion including ARID1B in chromosomal region 6q25, we performed mutational analysis in 887 unselected patients with unexplained ID. In this cohort, we found eight (0.9%) additional de novo nonsense or frameshift mutations predicted to cause haploinsufficiency. Our findings indicate that haploinsufficiency of ARID1B, a member of the SWI/SNF-A chromatin-remodeling complex, is a common cause of ID, and they add to the growing evidence that chromatin-remodeling defects are an important contributor to neurodevelopmental disorders.

Aging and Down Syndrome

The initial clinical description of Down syndrome (DS) was made by Down in 1866 [1] and identified as trisomy of chromosome 21 by Lejeune et al. in 1959 [2]. DS, or trisomy 21, is one of the most common causes of intellectual disability (ID), and recent national prevalence estimates suggest that 14.47 per 10,000 live births are infants with DS, leading to an average of 6037 annual DS births [3]. This represents an increase from previous prevalence rates. Characteristic physical features, deficits in the immune and endocrine systems, and delayed cognitive development [4] can be present in children with DS. Improvements in medical care for children and adults with DS have led to significant extensions in lifespan and enhanced quality of life. As a consequence, up to 35 years of age, mortality rates are comparable in adults with DS to individuals with ID from other causes. However, after age 35, mortality rates double every 6.4 years in DS, as compared to 9.6 years for people without DS [5], and the currently estimated life expectancy of a 1-year-old child with DS is between 43 and 55 years (depending on the level of disability). Although longevity in adults with DS has been increasing progressively, these increases have been substantially lower for some minority groups [6, 7]. Further, as described by L. Thorpe et al., adults with DS are still disadvantaged compared to adults with other types of ID in terms of mortality rate, with multiple comorbidities being of significant concern (e.g., depression, seizures). Significant contributors to quality of life in aging individuals with DS also include gait disturbances (B. A. Smith et al.) and ophthalmic disorders (e.g., S. J. Krinsky-MC. Hale et al.), both of which increase with age.

Sleep patterns and behaviour in typically developing children and children with autism, Down syndrome, Prader-Willi syndrome and intellectual disability

Sleep problems have often been reported in children with intellectual disabilities (ID). How anomalies in 24-h sleep patterns relate to behaviour difficulties in children with different types of ID remains to be elucidated. The purpose of this study was to assess 24-h sleep and behaviour patterns in children with a variety disorders including autism ( n = 34), Down syndrome (DS, n = 12), Prader-Willi syndrome ( n = 12), and children with intellectual impairments due to unknown etiologies ( n = 24). 33 typically developing (TD) children served as a control group. 24-h sleep and behavioural data were accumulated over a 14-day period using diary methodology. Group differences in daytime behaviour and sleep patterns were noted with children with DS being quieter, having higher levels of daytime sleepiness, and being better behaved than children with autism. Daytime napping was significantly more prevalent in children with PWS than children with autism and TD children. At bedtime children with autism were less likely to be sleepy, and were poorly behaved, which was reflected in a longer sleep latency and later time asleep. Poorer night-time sleep quality and reduced 24-h sleep time were also noted in the autism group. These findings are of clinical importance, as they indicate that different interventions may be required to treat sleep and behaviour problems in children with different developmental disabilities.