Aggressive behavior problems in children with autism spectrum disorders: Prevalence and correlates in a large clinical sample

Highlights

• Aggressive behavior problems (ABP) were present in 25% of children with ASD.

• ABP were predicted by comorbid sleep, internalizing, and attention problems.

• Attention to comorbid problems may aid in clinical treatment and counseling of ABP.

Abstract

Aggressive behavior problems (ABP) are frequent yet poorly understood in children with autism spectrum disorders (ASD) and are likely to co-vary significantly with comorbid problems. We examined the prevalence and sociodemographic correlates of ABP in a clinical sample of children with ASD (N = 400; 2–16.9 years). We also investigated whether children with ABP experience more intensive medical interventions, greater impairments in behavioral functioning, and more severe comorbid problems than children with ASD who do not have ABP. One in four children with ASD had Child Behavior Checklist scores on the Aggressive Behavior scale in the clinical range (T-scores ≥ 70). Sociodemographic factors (age, gender, parent education, race, ethnicity) were unrelated to ABP status. The presence of ABP was significantly associated with increased use of psychotropic drugs and melatonin, lower cognitive functioning, lower ASD severity, and greater comorbid sleep, internalizing, and attention problems. In multivariate models, sleep, internalizing, and attention problems were most strongly associated with ABP. These comorbid problems may hold promise as targets for treatment to decrease aggressive behavior and proactively identify high-risk profiles for prevention.

Introduction

Aggressive behaviors in children with autism spectrum disorder (ASD) are the primary cause of residential placement (Mandell, 2008) and are associated with greater functional impairment and more intensive medical interventions (Lecavalier, 2006, Tureck et al., 2013, Witwer and Lecavalier, 2005). Additionally, aggressive behaviors in children with ASD are a frequent source of parental concern (Mazurek, Kanne, & Wodka, 2013) and are known to increase family stress, financial strain, and demands on caregivers (Hodgetts et al., 2013, Lecavalier et al., 2006). While aggressive behavior in ASD is important due to the detrimental effects on caregiving, it may also be a risk factor for later poor outcomes. For instance, in the general population, aggressive behavior in childhood is linked to other maladaptive behaviors including delinquency/conduct problems, emotional dysregulation, low peer acceptance, and peer rejection (Card, Stucky, Sawalani, & Little, 2008). However, despite the clinical significance of aggressive behaviors in ASD, the prevalence and correlates of these behaviors are poorly understood.

Previous research suggests that aggressive behaviors are more common among children with ASD than in other populations (Bronsard et al., 2010, Farmer and Aman, 2011, Mayes et al., 2012, McClintock et al., 2003). However, prevalence estimates of aggressive behaviors in children with ASD vary widely, ranging from 8% to 68% (see Table 1). This variation is likely due to differences in the definitions of aggressive behaviors, the measures used, and the sample ascertainment methods. Estimates are considerably higher when based on non-standardized measures of parent-reported aggressive behavior. For example, Kanne and Mazurek (2011) estimated the prevalence of current aggressive behavior as 56%, based on parent ratings of mild to severe physical aggression on a single item on the Autism Diagnostic Interview-Revised. In a recent study using a large sample (N = 1584) from the Autism Treatment Network (ATN), the prevalence of aggressive behavior was 53.7%, based on a yes or no response from parents about whether aggressive behaviors were a current concern (Mazurek et al., 2013). However, these estimates are difficult to evaluate, particularly when samples encompass children within a wide age range, because it is not known how parents of children without ASD at different ages would respond.

In contrast, studies that have used validated measures of aggression tend to report lower prevalence estimates (see Table 1). For example, two previous studies measured aggressive behaviors using the Child Behavior Checklist (CBCL; Achenbach and Rescorla, 2000, Achenbach and Rescorla, 2001), a standardized measure with satisfactory national norms and with demonstrated reliability and validity in both clinical and non-clinical populations. In these studies, aggressive behavior problems (ABP), defined as CBCL aggressive behavior T-scores in the clinical range (≥70), were present in 8–23% of children with ASD (Georgiades et al., 2011, Hartley et al., 2008). However, both studies included only young children, limiting the generalizability of the findings and the ability to examine age trends. Therefore, clarification is needed to identify accurate rates of aggressive behavior problems in populations with ASD, to determine whether these rates vary systematically with age, and to better understand the factors associated with increased risk of such behaviors.

In the general population, the developmental course and correlates of aggressive behaviors have been well studied (Broidy et al., 2003, Nagin and Tremblay, 2001, NICHD Early Child Care Research Network, 2004, Tremblay et al., 2004). Instrumental physical aggressive behaviors reliably peak at about 24 months of age and decline thereafter (Nagin and Tremblay, 1999, NICHD Early Child Care Research Network, 2004). Family variables such as low family income, low parent education levels, maternal antisocial behavior, maternal depression, and maternal early onset of childbearing account for significant variability in aggressive behaviors in typically developing children (Gross et al., 2008, Nagin and Tremblay, 2001, Tremblay et al., 2004). Additionally, higher rates of aggressive behaviors are associated with male sex (Lansford et al., 2006, NICHD Early Child Care Research Network, 2004), early language delays (Dionne et al., 2003, Séguin et al., 2009, Van Daal et al., 2007), lower intellectual functioning (Tremblay, 2000), and higher levels of hyperactivity (Nagin & Tremblay, 2001). In most population samples, there are few children with significant aggressive behaviors who do not also exhibit clinically significant inattention/hyperactivity (Jester et al., 2005, Nagin and Tremblay, 2001).

Yet few of the factors associated with aggressive behaviors in typically developing populations have been consistently associated with aggressive behaviors in children with ASD. For example, the association between aggressive behavior and age is not clear. Higher levels of aggressive behaviors (primarily physical) have been found in younger children in some studies (Kanne and Mazurek, 2011, Mazurek et al., 2013), but not in others (Farmer and Aman, 2011, Hartley et al., 2008, Maskey et al., 2013, Murphy et al., 2005, Sikora et al., 2008). Gender has consistently not been associated with aggressive behavior in children with ASD as in typical populations (Farmer and Aman, 2011, Hartley et al., 2008, Kanne and Mazurek, 2011, Kozlowski et al., 2012, Mazurek et al., 2013, Murphy et al., 2009, Sikora et al., 2008). In terms of family demographics, higher levels of aggressive behaviors in children with ASD have been linked to both lower parent education levels (Mazurek et al., 2013) and higher family incomes (Kanne & Mazurek, 2011), leaving some question as to how aggression relates to family socio-economic status. Finally, similar to findings in typically developing children, increased aggressive behaviors have been found among children with ASD with impaired cognitive functioning (Dominick, Davis, Lainhart, Tager-Flusberg, & Folstein, 2007), language (Dominick et al., 2007, Hartley et al., 2008), and adaptive skills (Hartley et al., 2008, Mazurek et al., 2013), though negative findings have also been reported (Kanne and Mazurek, 2011, Maskey et al., 2013, Mazurek et al., 2013, Murphy et al., 2009).

Aggressive behaviors may also be influenced by the severity of a child's ASD symptoms (Jang, Dixon, Tarbox, & Granpeesheh, 2011). In one study, aggressive children (based on parent report) had more severe parent-reported (but not clinician-observed) social and communicative deficits (Kanne & Mazurek, 2011). Aggressive behaviors have also been linked to increased repetitive, stereotyped, and ritualistic behaviors as well as resistance to change in children with ASD (Dominick et al., 2007, Kanne and Mazurek, 2011).

In addition to core ASD symptoms, having ASD increases the risk of a number of comorbid problems that are known to increase challenging behavior in this population (Matson and Kuhn, 2001, Matson et al., 2011, Matson et al., 2010). Several of these comorbid problems have been associated with increased aggression among atypically and typically developing children. In children with ASD, increased aggressive behavior has been concurrently associated with greater sleep difficulties (Goldman et al., 2012, Mayes and Calhoun, 2009, Mazurek et al., 2013), internalizing symptoms (Cervantes et al., 2013, Kim et al., 2000), and hyperactivity and attention deficits (Yerys et al., 2009). However, studies linking psychiatric comorbidities to aggressive behaviors have either focused only on toddlers with ASD (Cervantes et al., 2013) or have been limited by relatively small research samples due to their study designs and aims (Kim et al., 2000, Yerys et al., 2009). No previous studies have examined comorbid sleep and behavioral/emotional problems in the same sample. These comorbid problems are likely to co-vary significantly with aggressive behaviors in children with ASD.

A better understanding of the correlates of ABP in children with ASD would provide insight into the pathophysiology of aggressive behaviors in ASD and would also have direct clinical implications. For example, clinicians could use the study's results to proactively counsel families of children with ASD who are at high risk for ABP. In addition, identifying modulating factors for some comorbid conditions, such as sleep or behavioral/emotional problems, could have a positive impact on children's aggressive behavioral symptoms and family stress.

The first aim of the current study was to examine the prevalence of ABP using the CBCL, a well-validated measure, in a large clinical sample of children with confirmed diagnoses of ASD. The second aim was to examine whether correlates associated with increased aggressive behaviors in typical populations would be similarly associated with the presence of ABP in children with ASD (child age, gender, parent education, race/ethnicity). Our final aim was to examine differences between children with and without ABP to determine whether those with ABP receive more intensive medical interventions (complementary/alternative medicines, psychotropic medications), demonstrate more severe impairments in behavioral functioning (ASD symptoms, adaptive skills, intellectual and language levels), and experience more severe comorbid problems (sleep, internalizing, and attention).