Aggression In Children and Adolescents with ASD: Prevalence and Risk Factors

Background:

Although aggression is generally understood to be a common problem among individuals with autism spectrum disorders (ASD), there have been no studies examining the prevalence of and risk factors for aggression among children and adolescents with a diagnosis of an ASD. Rates of aggression in ASD have ranged from 15% to 36% depending on how aggression was defined and in what age range, and some researchers have found that the presence of aggression was associated with lower IQ, poorer expressive and receptive language, and restricted and repetitive behaviors.

Objectives:

The current study is the first to report prevalence rates of and risk factors for aggressive behaviors among a large, national sample of children and adolescents with well-characterized diagnoses of ASD. In addition to examining whether aggression was related to risk factors observed in non-ASD children (e.g., age, level of income, level of parental education, parental marital status, gender, cognitive and adaptive functioning, language and communication), we also examined whether ASD phenotypic variables, such as level of severity and specific ASD symptoms, were predictive of aggression.

Methods:

The sample included 1380 participants between the ages of 4 and 17 who had participated in the Simons Simplex Collection (SSC). The SSC is a North American multi-site, university-based research study that includes families with only one child with an ASD. Phenotypic information was gathered via the ADI-R, ADOS, SRS, RBS-R, PPVT-4, CBCL, various IQ measures, and the Vineland II. Four individual ADI-R item scores from the ADI-R were used to assess both current and historical aggression directed toward both caregivers and non-caregivers. In addition to correlational analyses, logistic regression examined whether specific variables were significantly related to the presence of aggression (N = 633).

Results:

Over half (56%) of the respondents were currently engaging in some form of aggressive actions towards caregivers, with fewer (32%) engaging in aggressive behaviors towards non-caregivers. Sixty-eight percent had demonstrated some form of aggression at some point to a caregiver, and 49% to non-caregivers. Aggressive behaviors were more likely with increases in repetitive behaviors, higher income, and increasing levels of ASD related social and communicative deficits. A significant effect for age was found with aggressive behaviors becoming less likely with increasing age. Repetitive behaviors that were significant predictors were self injurious behaviors, ritualistic behaviors, and resistance to change.

Conclusions:

The results reflect a high prevalence of aggressive behaviors in individuals with ASD. Aggression in the current sample was not associated with clinician observed severity of ASD symptoms, level of intellectual, language or communication skills, gender, level of parental education, or parent marital status. Those individuals who were younger, whose parents reported more ASD related social and communication difficulties, who engaged in more severe restricted and repetitive behaviors, and who had higher levels of family income were more likely to demonstrate aggression. Given the significant impact of aggression on individual and family outcomes, it is hoped that this knowledge will inform more targeted intervention efforts.