Developing and Validating a Definition of Impulsive/Reactive Aggression in Youth.

The goal of this study is to develop a rational data-driven definition of impulsive/reactive aggression and establish distinctions between impulsive/reactive aggression and other common childhood problems. This is a secondary analysis of data from Assessing Bipolar: A Community Academic Blend (ABACAB; N = 636, ages 5-18), Stanley Medical Research Institute N = 392, ages 5-17), and the Longitudinal Assessment of Manic Symptoms (LAMS; N = 679, ages 6-12) studies, which recruited youths seeking outpatient mental health services in academic medical centers and community clinics. Following Jensen et al.'s (2007) procedure, 3 judges independently rated items from several widely used scales in terms of assessing impulsive/reactive aggression. Principal components analyses (PCA) modeled structure of the selected items supplemented by items related to mood symptoms, rule-breaking behavior, and hyperactivity/impulsivity to better define the boundaries between impulsive/reactive aggression and other common childhood symptoms. In the rational item selection process, there was good agreement among the 3 experts who rated items as characterizing impulsive/reactive aggression or not. PCA favored 5 dimension solutions in all 3 samples. Across all samples, PCA resulted in rule-breaking behavior, aggression-impulsive/reactive (AIR), mania, and depression dimensions; there was an additional hyperactive/impulsive dimension in the LAMS sample and a self-harm dimension in ABACAB and Stanley samples. The dimensions demonstrated good internal consistency; criterion validity coefficients also showed consistency across samples. This study is a step toward developing an empirically derived nosology of impulsive aggression/AIR. Findings support the validity of the AIR construct, which can be distinguished from manic and depressive symptoms as well as rule-breaking behavior.