Impulsivity (or impulsiveness) is a multi-factorial construct that involves a tendency to act on a whim, displaying behavior characterized by little or no forethought, reflection, or consideration of consequences. Impulsive actions typically are “poorly conceived, prematurely expressed, unduly risky, or inappropriate to the situations that often result in undesirable consequences,” which imperil long term goals and strategies for success. A functional variety of impulsivity has also been suggested, which involves action without much forethought in appropriate situations that can and does result in desirable consequences. “When such actions have positive outcomes, they tend not to be seen as signs of impulsivity, but as indicators of boldness, quickness, spontaneity, courageousness, or unconventionality”. Thus, the construct of impulsivity includes at least two independent components:

(1). Acting without an appropriate amount of deliberation, which may or may not be functional.

(2). Choosing short-term over long-term gains.

asim Impulsivity is both a facet of normal personality as well as being a major component of various disorders including:  ADHD,  substance use disorders,  bipolar disorderantisocial personality disorder,  and borderline personality disorder. Abnormal patterns of impulsivity have also been noted instances of acquired brain injury and neurodegenerative diseases. Neurobiological findings suggest that there are specific brain regions involved in impulsive behavior although different brain networks may contribute to different manifestations of impulsivity, and that genetics may play a strong role. 

Many actions contain both impulsive and compulsive features, but impulsivity and compulsivity are functionally distinct. Impulsivity and compulsivity are interrelated in that each exhibits a tendency to act prematurely or without considered thought and often include negative outcomes. Compulsivity occurs in response to a perceived risk or threat, impulsivity occurs in response to a perceived immediate gain or benefit, and whereas compulsivity involves repetitive actions, impulsivity involves unplanned reactions.

Some individuals are often impulsive: They act without deliberation; they cannot resist temptations; they often engage in thrilling activities, and so forth. In general, impulsive tendencies increase the incidence of an extensive array of problems, from gambling and alcoholism to excessive use of mobile phones. Yet, in some instances, impulsivity can improve performance on particular tasks.

A Brief recently published in Science confirms the key role of dopamine in impulsive behavior, Joshua W.Buckholtz ( Harvard University, Psychology, faculty member ) and colleagues used dual-scan positron emission tomography in healthy human volunteers to gauge diminishing midbrain D2/D3 auto-receptor binding and greater amphetamine- induced dopamine  in the striatum where predictive of higher levels of trait impulsivity. The researchers found that impulse control directly correlated with the amount of dopamine released in the striatum. The further explored the relevance of enhanced striatal dopamine release to the risk of substance abuse. Their findings suggest that there is a neurological link between impulsiveness and drug abuse vulnerability increased dopamine release predicted a stronger desire for drugs. 

Substance abuse

Impulsivity appears to be linked to all stages of substance abuseThe acquisition phase of substance abuse involves the escalation from single use to regular use. Impulsivity may be related to the acquisition of substance abuse because of the potential role that instant gratification provided by the substance may offset the larger future benefits of abstaining from the substance, and because people with impaired inhibitory control may not be able to overcome motivating environmental cues, such as peer pressure.

Escalation or dysregulation is the next and more severe phase of substance abuse. In this phase individuals “lose control” of their addiction with large levels of drug consumption and binge drug use. Studies suggest that individuals with higher levels of impulsivity may be more prone to the escalation stage of substance abuse.

Impulsivity is also related to the abstinence, relapse, and treatment stages of substance abuse. Impulsive people have greater cravings for drugs during withdrawal periods and were more likely to relapse. Taken as a whole the current research suggests that impulsive individuals are less likely to abstain from drugs and more likely to relapse earlier than less impulsive individuals.

While it is important to note the effect of impulsivity on substance abuse, the reciprocating effect whereby substance abuse can increase impulsivity has also been researched and documented. The promoting effect of impulsivity on substance abuse and the effect of substance abuse on increased impulsivity creates a positive feedback loop that maintains substance seeking behaviors. It also makes conclusions about the direction of causality difficult. This phenomenon has been shown to be related to several substances, but not all. For example, alcohol has been shown to increase impulsivity while amphetamines have had mixed results.