Neuropsychological Factors in Impulsive Aggression and Violent Behavior

Episodically aggressive offenders, both impulsive and predatory, constitute one of the most pressing problems for law enforcement, courts, and corrections, not to mention the general public. This subgroup of offenders is largely responsible for the following: (a) a disproportionate amount of aggressive crimes against persons, (b) high recidivism rates, (c) a significant number of institutional rule violations, (d) high rates of substance abuse, and (e) intractability and poor treatment outcomes. Repetitively aggressive offenders are often diagnosed with antisocial personality disorder (ASPD), and a subset of these as psychopathic. Their personal histories are typified by childhood aggression, insensitivity to punishment, emotional dysregula-tion, risk taking, and sensation seeking. These inmates are recommitted more often than other inmates, a majority of them recidivate with aggressive offenses, and they are likely to develop an early and more severe course of drug abuse. Yet few community, private, or correctional programs are available to treat these offenders or, more importantly, to prevent the development of these behaviors before they stabilize. There are clear public safety benefits to being able to accurately identify and characterize these offenders in terms of conditions that may underlie or contribute to their dysregulated behavior in order to direct more effectively treatment and prevention resources.

Recent research on underlying mechanisms in aggression may be applicable to this problem and has implications for more effective interventions. Various neuropathological conditions (attenuated frontal P300 amplitude, reduced prefrontal glucose metabolism, subdued physiological responses to alcohol, neuropsychological deficits, differences in neurotransmitter metabolism and activity levels, and heightened stress dampening) have been associated with these [Page 482]dysregulated behaviors, suggesting that neurobiologi-cal processes may underlie risky behaviors. In particular, studies have consistently found that deficits in certain neuropsychological functions correlate with and predict aggression, impulsivity, violence, and other forms of persistent misconduct in both children and adults. What is emerging from these studies is that although many offenders may function adequately in terms of basic cognitive skills such as memory, intelligence, and learning ability, those who repeatedly engage in very risky behaviors may have deficits in what is called executive cognitive functions (ECFs), higher-order neuropsychological skills. ECFs include a subset of higher-order neuropsychological abilities and their measurement has become more refined, non-invasive, and reliable, making it more amenable to conducting these studies with offenders.

ECF abilities include social skills, impulse control, assessment of and sensitivity to consequences, motivation, attention, and emotional perception and regulation. Deficits in these abilities have been implicated in aggression and are thought to be responsible for a number of traits often seen in aggressive offenders, such as poor social skills and decision-making ability, insensitivity to punishment, impulsivity, inattention, impaired problem solving, cognitive inflexibility, and lack of goal-directed behaviors. And because ECFs regulate and, in most cases, inhibit emotional responses, ECF deficits are also associated with poor emotional regulation and inaccurate perceptions of emotion in others. In essence, impaired ECF may compromise the ability to interpret social cues during interpersonal interactions, which may lead to misper-ceptions of threat or hostility. As a result, difficulties arise in generating socially adaptive behaviors and in executing responses to avoid aggressive or stressful interactions. Also, compromised cognitive control over behavior may permit hostility, negative affective states, and other maladaptive responses to dominate.

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