Aggression is a clinically significant feature of many children and adolescents with autism spectrum disorder (ASD). Children with ASD frequently have co-occurring (comorbid) psychiatric conditions, with estimates as high as 70 to 84 percent. These co-occurring problems often exacerbate the core symptoms of ASD and can lead to significant functional impairment. Among these problems, physical aggression appears to be especially challenging, and has been associated with serious negative outcomes in both the general population and among individuals with ASD. For example, challenging behaviors can interfere with interventions and the child’s ability to succeed at school. They may cause a child to be excluded from community activities, such as after-school programs, scouting and sports. Fear of aggressive incidents may also keep families at home, increasing their sense of isolation and decreasing their quality of life.
Research
Although the nature and
developmental course of aggression have been a focus of research with typically
developing populations, there have been few large-scale studies of group-level
predictors of aggression among individuals with ASD. Consequently, it is unclear
whether findings from the general population are applicable to children and
adolescents with ASD. In an effort to investigate the extent of the problem in
children and adolescents with ASD, a recent large-scale study published in Research in Autism Spectrum
Disorders examined the prevalence and correlates of physical aggression in
a sample of 1584 children and adolescents with ASD enrolled in the Autism
Treatment Network (ATN), a multi-site network of 17 autism centers across the
US and Canada. Participants in the study ranged in age from 2 to 17 years, with a mean age of 5.91 years. The
term “aggression” referred specifically to physical aggression and included
biting, hitting, or other physical aggression directed towards others. A number
of diagnostic, medical, and behavioral measures were collected at enrollment
and at regular follow-up intervals. Measures of interest included: (a)
aggression, (b) sleep disturbance, (c) sensory problems, (d) communication and
social functioning, (e) self-injury and gastrointestinal problems, (f) cognitive
functioning, and (g) verbal/nonverbal status. Data analyses were completed in
order to identify the variables most strongly associated with aggression.
What are the Predictors of Aggression?
The results indicated that
the prevalence of aggression was 53% across the entire sample of children, with
highest prevalence among young children. These results are highly consistent
with recently reported prevalence rates (56%) in another large-scale study of
children and adolescents with ASD. The results also indicate that age-related
decreases in aggression in children with ASD are similar to what has been
observed in typically developing children. It should be noted, however, that a large
percentage (nearly 50%) of the adolescents in the study’s sample continued to demonstrate
physical aggression. Thus, the relative decrease in aggression over time must
be balanced by the finding that these behaviors continued to occur at a high rate
among a large portion of adolescents with ASD.
In terms of predictors, the
results indicated that self-injury was highly associated with aggression among
children with ASD. This is consistent with the findings of other studies
showing a strong association between self-injury and other challenging
behaviors. The current results add to existing literature, and suggest that
children with ASD who demonstrate self-injury may be at risk for more severe
behavioral problems.
Sleep problems emerged as
a second significant predictor aggression. This association between sleep
problems and aggression is largely consistent with previous findings among both
typically developing children and those with ASD, indicating may underlie (and
exacerbate) aggressive behavior patterns for many children with ASD. It should
also be noted that sleep problems have been found to be associated with
self-injurious behaviors among individuals with intellectual disabilities and
that these two conditions may be related. In fact, there is some developing evidence
suggesting shared neurobiological basis for both sleep disturbance and
self-injurious behavior.
Sensory problems were also
significantly associated with aggression. These findings are consistent with
similar associations between sensory issues and aggression among typically developing
children. While previous research has demonstrated an association between
sensory problems and broadly defined behavior problems, the current results
extend these previous findings by demonstrating a specific relationship between
sensory problems and physical aggression.
Comparisons also indicated
that children with aggression were more likely to experience GI problems,
communication skill difficulties, and social skills difficulties. However,
these variables did not appear as significant predictors of aggression,
indicating that self-injury, sleep problems, and sensory issues accounted for
the majority of the variance in predicting aggression.
In terms of potential sex
differences, the results indicate that girls and boys with ASD were equally
likely to engage in aggression. This finding was unexpected in that research
has consistently shown a significant gender difference among children without
ASD, with boys being much more likely to engage in physical aggression than
girls. The results of the study suggest that the sex differential in aggression
may not be salient in the ASD population.
Implications
This study provides
evidence that challenging behavior may be much more prevalent among children with ASD
than in the general population and that some comorbid problems may place
individuals at risk for aggression. Aggression was significantly associated
with a number of clinical features, including self-injury, sleep problems,
sensory problems, GI problems, and communication and social functioning.
However, self-injury, sleep problems, and sensory problems were most strongly
associated with aggression. These findings indicate that co-occurring problems
specific to the ASD phenotype may play an important role in the occurrence of
aggression and that it is important to consider multiple domains of functioning
when assessing and treating aggression in children with ASD. For example, increased
attention should be given to the identification and treatment of sleep
problems, self-injury, and sensory problems. Given the significant relationship
between sleep problems and aggression, it is possible that treatments targeting
sleep problems may help reduce maladaptive behavior. Thus, assessment and
treatment of sleeping problems might be included as a standard and integrated
part of the assessment and treatment of ASD. Programs for children with ASD
should also integrate an appropriately structured physical and sensory milieu
in order to accommodate any unique sensory processing challenges. Although
assessment tools are limited, comorbid problems should be assessed whenever
significant behavioral issues (e.g., inattention, mood instability, anxiety,
sleep disturbance, aggression) become evident or when major changes in behavior
are reported. Co-occurring disorders should also be carefully investigated when
severe or worsening symptoms are present that are not responding to traditional
methods of intervention.
More research
is needed in order to better understand the characteristics and course of
different types of aggression. For example, future research should examine the
longitudinal course of aggression, the role of these associated problems in
predicting improvement or worsening of aggression, and possible changes in
aggression in response to treatment for these co-occurring problems. Studies
are also needed to examine the role of additional family- and community-level
variables in the prediction and maintenance of aggression among children with
ASD.
References
Mazurek, M. O., Kanne, S. M., & Wodka, E. L. (2013). Physical aggression in children and adolescents with autism spectrum disorders. Research in Autism Spectrum Disorders, 7, 455–465.
Hill, A.P., Zuckerman, K.E., Hagen, A.D., Kriz,
D.J., Duvall, S.W., Santen, J., Nigg, J., Fair, D., & Fombonne, E. (2014). Aggressive
behavior problems in children with autism spectrum disorders: Prevalence and
correlates in a large clinical sample. Research in Autism Spectrum Disorders, 8, 1121-1133.
Wilkinson, L. A. (2017). A best practice guide to assessment and intervention for autism spectrum disorder in schools (2nd Edition). London & Philadelphia: Jessica Kingsley Publishers.
Wilkinson, L. A. (2017). A best practice guide to assessment and intervention for autism spectrum disorder in schools (2nd Edition). London & Philadelphia: Jessica Kingsley Publishers.
Lee A.
Wilkinson, PhD is
a licensed and nationally certified school psychologist, and certified cognitive-behavioral therapist. He is author of the
award-winning books, A Best Practice Guide to Assessment and Intervention for
Autism and Asperger Syndrome in Schools and Overcoming Anxiety on the Autism Spectrum: A Self-Help
Guide Using CBT. He is also editor of a text in the APA School Psychology Book Series, Autism Spectrum Disorder in Children and Adolescents:
Evidence-Based Assessment and Intervention in Schools. His
latest book is A Best Practice Guide to Assessment and Intervention for
Autism Spectrum Disorder in Schools (2nd Edition).