Objectives: The purpose of the present study was to examine the effectiveness of adding IBI to medication in the treatment of aggressive behavior in youth with ASD.
Methods: Youth with a DSM-IV diagnosis of Autistic Disorder or Pervasive Developmental Disorder NOS were eligible for inclusion if they received an IBI plan targeting aggressive behavior. Each participant received IBI for >/=30 hours/week, comprised of at least six hours per day, five days per week year round. Any participant with at least four aggressive behaviors per day and at least one day per week of multiple aggressive behaviors was eligible to be placed on an aggression behavior reduction plan. Aggressive behavior was defined as any behavior that either harms or attempts to harm another person or causes destruction of property. Inclusion criteria were intentionally broad to enhance the generalizabilty of this effectiveness study (Ernst and Pittler 2006; Gartlehner, et al. 2006). Youth were prescribed medication by their treating physician. Medication usage was recorded for all participants. Three medication classes were coded based upon the pattern of specific medication usage observed in this sample: 1) antipsychotics, 2) mood stabilizers, and 3) non-stimulant medications treating ADHD and/or sleep symptoms. To determine the effectiveness of medication classes, a Cox regression analysis was computed with medication classes as predictors, the number of behavior plan sessions as the time variable, and success of the behavior plan as the endpoint/status variable.
Results: Thirty-two youth with ASD (Mean Age = 11.16, SD=3.31; range=4-16, 75% male) received a behavior reduction plan targeting aggression. Of these, 18, 10, and 12 were taking antipsychotic, mood stabilizing, and non-stimulant medications. The presence of antipsychotic medication significantly decreased the number of sessions required to achieve behavior plan success (Χ2(1)=5.67, p=.017; no antipsychotic - Mean=228.1, SE=52.9, Median=149.0, SE=60.8, 95% CI=29.8-268.2; antipsychotic - Mean=83.2, SE=29.6, Median=30, SE=4.2, 95% CI=21.7-38.3). No other medication classes significantly influenced aggressive behavior.
Conclusions: IBI alone, while showing substantial decreases in aggressive behavior, was more effective when paired with antipsychotic medication. These findings extend previous efficacy data for antipsychotics (Kratochvil, et al. 2005; McCracken, et al. 2002; McDougle, et al. 2005) by demonstrating effectiveness in augmenting behavior therapy in the treatment of aggression. Furthermore, results of the present study suggest that a combined antipsychotic-IBI treatment approach warrants further exploration in larger-scale efficacy and effectiveness studies. Mood stabilizing medications and non-stimulant medications used to treat ADHD symptoms and/or sleep difficulties (primarily clonidine) were not effective in reducing aggressive behavior.