Self-injurious behaviour is prevalent in individuals with ASD and the presence of ASD phenomenology increases the risk of self-injury in individuals with known genetic disorders but without a diagnosis of idiopathic autism. Person characteristics associated with self-injury in ASD indicate a role for impaired behavioural inhibition, low levels of ability and negative affect in the development of self-injurious behaviour.

We evaluated the proportion of individuals with Down syndrome (DS: N = 108) who met criteria for autism spectrum disorder (ASD) on the Social Communication Questionnaire and the severity of ASD-related symptomatology in this group. The proportions of individuals with DS meeting the cut-off for ASD and autism in this sample were 19% and 8%, respectively. We then evaluated the behavioural profile of individuals with DS who scored above cut-off for ASD (DS+ASD; N = 17) compared with those with DS-only (N = 17) and individuals with idiopathic ASD (N = 17), matched for adaptive behaviour skills and ASD symptom severity (ASD group only). Individuals in the DS+ASD and ASD-only groups showed more stereotyped behaviour, repetitive language, overactivity and self-injury than the DS-only group (p < .001). Individuals in the DS+ASD and DS-only groups appeared less withdrawn from their surroundings than those with ASD (p < .004). These findings indicate differences in the behavioural and cognitive profile of individuals with DS+ASD compared with those with DS-only, when controlling for adaptive behaviour skills. Individuals with DS+ASD show broad similarities with individuals with idiopathic ASD with regard to ASD and behavioural characteristics but may also show some areas of subtle difference from this group.

BackgroundThere are few studies documenting the persistence of self-injury in individuals with autism spectrum disorder (ASD) and consequently limited data on behavioural and demographic characteristics associated with persistence. In this longitudinal study, we investigated self-injury in a cohort of individuals with ASD over 3 years to identify behavioural and demographic characteristics associated with persistence.MethodsCarers of 67 individuals with ASD (Median age of individuals with ASD in years = 13.5, Interquartile Range = 10.00–17.00), completed questionnaires relating to the presence and topography of self-injury at T1 and three years later at T2. Analyses were conducted to evaluate the persistence of self-injury and to evaluate the behavioural and demographic characteristics associated with persistence of self-injury.ResultsAt T2 self-injurious behaviour had persisted in 77.8 % of individuals. Behavioural correlates of being non-verbal, having lower ability and higher levels of overactivity, impulsivity and repetitive behaviour, were associated with self-injury at both time points. Risk markers of impulsivity (p = 0.021) and deficits in social interaction (p = 0.026) at T1 were associated with the persistence of self-injury over 3 years.ConclusionsImpulsivity and deficits in social interaction are associated with persistent self-injury in ASD and thus may act as behavioural risk markers. The identification of these risk markers evidences a role for behaviour dysregulation in the development and maintenance of self-injury. The findings have clinical implications for proactive intervention; these behavioural characteristics may be utilised to identify ‘at risk’ individuals for whom self-injury is likely to be persistent and therefore those individuals for whom early intervention may be most warranted.

An atypical presentation of autism spectrum disorder is noted in Cornelia de Lange and Fragile X syndromes, but there are few detailed empirical descriptions. Participants in this study were individuals with Cornelia de Lange syndrome (n  =  130, M age  =  17.19), Fragile X syndrome (n  =  182, M age  =  16.94), and autism spectrum disorder (n  =  142, M age  =  15.19), who were comparable on chronological age. Using the Social Communication Questionnaire, the proportion meeting cutoff for autism spectrum disorder and autism was 78.6%, and 45.6%, respectively, in Cornelia de Lange syndrome and 83.6% and 48.6% in Fragile X syndrome. Domain and item analyses indicate differing, atypical autism spectrum disorder profiles in Fragile X and Cornelia de Lange syndromes. A limited association between adaptive behavior and autism spectrum disorder was identified in all groups. The findings have implications for intervention in genetic syndromes and conceptualization of autism spectrum disorder in the wider population.

Few comparative studies have evaluated the heterogeneity of sociability across a range of neurodevelopmental disorders. The Sociability Questionnaire for People with Intellectual Disability (SQID) was completed by caregivers of individuals with Cornelia de Lange (n = 98), Angelman (n = 66), Fragile X (n = 142), Down (n = 117) and Rubinstein Taybi (n = 88) syndromes and autism spectrum disorder (ASD; n = 107). Between groups and age-band (<12yrs; 12-18yrs; >18yrs) comparisons of SQID scores were conducted. Rates of behaviors indicative of selective mutism were also examined. Fragile X syndrome achieved the lowest SQID scores. Cornelia de Lange, ASD, and Fragile X groups scored significantly lower than Angelman, Down and Rubinstein Taybi groups. Selective mutism characteristics were highest in Cornelia de Lange (40%) followed by Fragile X (17.8%) and ASD (18.2%). Age-band differences were identified in Cornelia de Lange and Down syndrome.