Co-occurring Down Syndrome and Autism Spectrum Disorder: Cognitive, Adaptive, and Behavioral Characteristics

Implementation of the International Classification of Diseases 11th revision behavioural indicators for disorders of intellectual development with co-occurring autism spectrum disorder

BACKGROUND

The classification of mental, behavioural and neurodevelopmental disorders in the World Health Organization's International Classification of Diseases 11th revision (ICD-11) includes a comprehensive set of behavioural indicators (BIs) within the neurodevelopmental disorders grouping. BIs can be used to assess the severity of disorders of intellectual development in situations in which standardised measures of intellectual functioning and adaptive behaviours are not available or feasible. This international study examines the implementation characteristics of the BIs and compares them to standardised measures for assessing the severity of intellectual impairment and adaptive behaviours in disorders of intellectual development and autism spectrum disorder (ASD). The clinical utility of the ICD-11 and the fidelity of its application in international clinical settings were also assessed.

METHODS

A total of 116 children and adolescents (5-18 years old) with a suspected or established diagnosis of disorders of intellectual development were included across four sites [Italy (n = 18), Sri Lanka (n = 19) and two sites in India (n = 79)]. A principal component analysis was conducted to evaluate the application of the ICD-11 guidance for combining severity levels.

RESULTS

Assessment using the BIs showed a higher proportion of individuals classified with mild severity, whereas the standardised measures indicated a higher proportion of severe ratings. Additionally, individuals with co-occurring ASD tended to have more severe impairments compared with those without ASD, as indicated by both BIs and standardised measures. Overall, the BIs were considered clinically useful, although more time and consideration were required when applying the guidelines for individuals with a co-occurring disorder of intellectual development and ASD. The principal component analysis revealed one principal component representing overall disorders of intellectual development severity levels.

CONCLUSIONS

The ICD-11 BIs can be implemented as intended in international clinical settings for a broad range of presentations of individuals with neurodevelopmental disorders. Use of the BIs results in similar severity diagnoses to those made using standardised measures. The BIs are expected to improve the reliability of severity assessments in settings where appropriate standardised measures for intellectual and adaptive behaviours are not available or feasible.

Pragmatic competence in people with dual diagnosis: down syndrome and autism spectrum disorder

BACKGROUND

Pragmatics is an area that can be affected in a wide variety of disorders. In this sense, Syndromic Autism is defined as a disorder in which a causal link is established between an associated syndrome and Autism Spectrum Disorder (ASD). Likewise, Down Syndrome (DS) is one of the main genetically based syndromes in which ASD is described as one of its possible manifestations. In this direction, people with DS are described as social beings whereas in ASD there seems to be a specific alteration of this domain.

METHODS

In this study, pragmatic performance was analysed in a sample of 72 participants, where comparisons were made between the scores obtained by children with ASD (n = 24), with DS (n = 24) and with DS + ASD (n = 24).

RESULTS

The Social Communication Questionnaire (SCQ), the Block Objective and Criterial Language Battery (BLOC-SR) and the Neuropsychology subtest (NEPSY-II) aimed at Theory of Mind (ToM) identified significant differences between the groups. However, two-to-two comparisons reported no significant differences between DS and DS + ASD.

CONCLUSIONS

Although several studies report differences between the three proposed groups, our data seem to suggest that ASD symptomatology in DS is associated with Intellectual Developmental Disorder (IDD). However, the lack of solid scientific evidence regarding comorbid diagnosis makes further research along these lines indispensable.

TRIAL REGISTRATION

This study was approved by the Ethics Committee for Social Research at UCLM with reference CEIS-704,511-L8M4.

Heterogeneity of Autism Characteristics in Genetic Syndromes: Key Considerations for Assessment and Support

Purpose of Review

Elevated prevalence of autism characteristics is reported in genetic syndromes associated with intellectual disability. This review summarises recent evidence on the behavioural heterogeneity of autism in the following syndromes: Fragile X, Cornelia de Lange, Williams, Prader-Willi, Angelman, Down, Smith-Magenis, and tuberous sclerosis complex. Key considerations for assessment and support are discussed.

Recent Findings

The profile and developmental trajectory of autism-related behaviour in these syndromes indicate some degree of syndrome specificity which may interact with broader behavioural phenotypes (e.g. hypersociability), intellectual disability, and mental health (e.g. anxiety). Genetic subtype and co-occurring epilepsy within syndromes contribute to increased significance of autism characteristics. Autism-related strengths and challenges are likely to be overlooked or misunderstood using existing screening/diagnostic tools and criteria, which lack sensitivity and specificity within these populations.

Summary

Autism characteristics are highly heterogeneous across genetic syndromes and often distinguishable from non-syndromic autism. Autism diagnostic assessment practices in this population should be tailored to specific syndromes. Service provisions must begin to prioritise needs-led support.

Developmental Functioning of Toddlers At-Risk for Autism With and Without Down Syndrome

PURPOSE

Due to the difficulties in differentiating between impairments associated with intellectual disability and ASD symptomology, DS often leads to delayed or misdiagnoses of ASD.

METHOD

An ANOVA was run to investigate the effects of ASD risk and DS on overall developmental functioning across three groups: ASD+, DS-, and DS+ (n = 138). A MANOVA was run to investigate the differences of group on five developmental subdomains.

RESULTS

The results revealed significant group differences in the overall developmental functioning and each developmental subdomain. Children in the DS+ group demonstrated significantly lower overall developmental functioning, as well as lower adaptive, cognitive, motor, and communication skills compared to their peers; however, children in the DS- group demonstrated significantly better social skills compared to their peers in the ASD+ group.

DISCUSSION

These findings support the need for early screening and identification of ASD among those with DS.

Precision Autism: Genomic Stratification of Disorders Making Up the Broad Spectrum May Demystify Its "Epidemic Rates"

In the last decade, Autism has broadened and often shifted its diagnostics criteria, allowing several neuropsychiatric and neurological disorders of known etiology. This has resulted in a highly heterogeneous spectrum with apparent exponential rates in prevalence. I ask if it is possible to leverage existing genetic information about those disorders making up Autism today and use it to stratify this spectrum. To that end, I combine genes linked to Autism in the SFARI database and genomic information from the DisGeNET portal on 25 diseases, inclusive of non-neurological ones. I use the GTEx data on genes’ expression on 54 human tissues and ask if there are overlapping genes across those associated to these diseases and those from SFARI-Autism. I find a compact set of genes across all brain-disorders which express highly in tissues fundamental for somatic-sensory-motor function, self-regulation, memory, and cognition. Then, I offer a new stratification that provides a distance-based orderly clustering into possible Autism subtypes, amenable to design personalized targeted therapies within the framework of Precision Medicine. I conclude that viewing Autism through this physiological (Precision) lens, rather than viewing it exclusively from a psychological behavioral construct, may make it a more manageable condition and dispel the Autism epidemic myth.

Symptoms of Autism Spectrum Disorder in Individuals with Down Syndrome

There is a growing body of evidence to suggest that individuals with Down syndrome (DS) are diagnosed with autism spectrum disorders (ASD) at a higher rate than individuals in the general population. Nonetheless, little is known regarding the unique presentation of ASD symptoms in DS. The current study aims to explore the prevalence and profiles of ASD symptoms in a sample of individuals with DS (n = 83), aged between 6 and 23 years. Analysis of this sample (MAge = 15.13) revealed that approximately 37% of the sample met the classification cut-off for ASD using the Autism Diagnostic Observation Schedule 2 (ADOS-2) Calibrated Severity Score (CSS), an indicator of the participants' severity of ASD-related symptoms. Item-level analyses revealed that multiple items on Module 2 and Module 3 of the ADOS-2, mostly in the Social Affect (SA) subdomain, differentiated the children with DS who did not meet ASD classification (DS-only) from those who did (DS + ASD). Lastly, comparisons of individuals with DS-only and those with DS + ASD differed significantly on the syntactic complexity of their expressive language. These findings shed light on the unique presentation of ASD symptoms in a sample of individuals with DS and suggest that expressive language abilities may play a pivotal role in the presentation of ASD symptoms in DS.