Impulsive aggression is the sudden and unpredictable use of force or violence by an individual. It is the action of automatically reacting violently to a stimulus without taking the time to consider the action or the consequences. It is unpremeditated and presents as a disproportionate reaction to a perceived provocation (whether it be real or imagined).
Physiologically, this is a result of an interaction of serotonin, the amygdala, and the prefrontal cortex. Impulsivity itself is frequently seen as a side-effect of several disorders such as ADHD, substance use disorders, bipolar disorder, antisocial personality disorder, psychopathy, and borderline personality disorder. Impulsive aggression is a primary symptom of Intermittent Explosive Disorder, a dangerous condition that causes an individual to suddenly react with aggression and rage for little or no obvious reason.