Impulsivity is defined as a behaviour that is connected to personality, temperament and mental health. Impulsivity is a predisposition to act hastily and with limited reflection on the possible outcomes. Impulsive behaviour can be described as a happy-go-lucky, act before thinking, unnecessarily risky and appropriate to the situation. Impulsivity might cause problems to concentrate as well. Excessive impulsivity is associated with mental conditions such as ADHD, substance use disorders, bipolar disorder, antisocial personality disorder and borderline personality disorder.
Impulsivity (from Latin impellere: to push, strike against; set in motion, drive forward, urge on) is multifaceted: it includes acting without thinking or without considering consequences, taking risks and responding to distracting stimuli. To determine whether impulsivity is ‘too high’ depends on how much it interferes with daily life. This, in turn, depends on a person’s age and cultural norms. Children are usually more impulsive than grown-ups, growing older we learn to better control our impulses.
People possess a relatively stable level of impulsivity (i.e. trait impulsivity) or are affected by circumstances inducing impulsivity (i.e. state impulsivity). Some level of impulsivity is present in all individuals and only exceeding/frequent levels pose a mental health/wellbeing problem. Examples of everyday expression of impulsivity may include: a drink too much at a party; an “impulse buy” of a candy bar at the supermarket till; or a hasty regretted insult in conversation.
The far end of impulsivity is, though, a hallmark of several mental health disorders – attention deficit hyperactivity disorder (ADHD); alcohol and drug use disorders, binge eating, bulimia, antisocial and borderline personality disorders, intermittent explosive disorder and the manic episode of bipolar disorder.
Being on the impulsive side does not necessarily cause problems. For a long time, impulsivity was seen as a negative characteristic, causing problems for the individual, their family and friends and for the society. Since the 1990’s Scott J. Dickman has distinguished between adaptive (functional) and maladaptive (dysfunctional) impulsivity. He brought out that impulsivity may be adaptive in certain circumstances, where fast responding is more important than accuracy. People with adaptive impulsivity are seen as livelier and more adventurous, as they are willing to take risks. So, impulsivity can be seen as a positive characteristic as well, because in some situations quick decisions are needed, even if they are not the best solutions. Maladaptive impulsivity can be described as thoughtlessness and inability to plan and can lead to negative consequences.
Most often impulsivity is assessed with self-report questionnaires, where people subjectively report how they usually behave or how they define themselves. Self-reports mainly indicate the trait-like, stable aspects of impulsivity. Typical questions in an impulsivity questionnaire may look like this: I am restless at the theatre or lectures; I buy things on impulse; I do things without thinking; I will often say whatever comes into my head without thinking first; I don’t like to make decisions quickly, even simple decisions, such as choosing what to wear, or what to have for dinner.
Besides self-reports, impulsivity can be measured with neuropsychological tests. The advantage of these tests, that usually look like simple computer games, is objectivity, the results do not rely on the persons subjective appraisal. Besides the trait-like properties of impulsivity these tests can also measure subtle changes in impulsivity levels. Two best-known examples of such tests are Go/NoGo task (https://www.psytoolkit.org/experiment-library/experiment_go-no-go.html) and Stop-Signal task (https://www.psytoolkit.org/experiment-library/experiment_stopsignal.html).
Neural substrate of impulsivity
Heritability of several forms of impulsivity has been estimated to approximately 40-45%. This means that less than half of the variation in impulsivity between people is explained by genetic factors. Neuroanatomically, the right prefrontal cortex is crucial for some forms of impulsivity, as shown by brain imaging studies. Patients with damage or transient dysfunction of this brain area have declined performance in neuropsychological tasks of impulsivity. Deficiencies in the brain of the neurotransmitter serotonin is characteristic of impulsivity and several impulse-related disorders.
Dopaminergic and noradrenergic drugs (for instance, Ritalin, Concerta, Strattera) improve symptoms of impulsivity, as seen from treatment results of ADHD children and adults. A brief intervention, consisting of a lecture on the essence of impulsivity, followed by a workshop, where impulsivity levels were measured and discussed, led to a long-lasting reduction impulsive behaviour in traffic.
More reading on Impulsivity from New Brain Nutrition
 American Psychiatric Association. Diagnostic and statistical manual of mental disorders (5th ed.). (American Psychiatric Association, 2013).
 Amlung, M. et al. Delay Discounting as a Transdiagnostic Process in Psychiatric Disorders: A Meta-analysis. JAMA Psychiatry 76, 1176–1186 (2019).
 Colman, A. A Dictionary of Psychology. (Oxford University Press, 2015).
 Congdon, E. & Canli, T. A neurogenetic approach to impulsivity. Journal of Personality 76, 1447–1484 (2008).
 Dickman, S. J. Functional and dysfunctional impulsivity: Personality and cognitive correlates. Journal of Personality and Social Psychology 58, 95–102 (1990).
 Evenden, J. L. Varieties of impulsivity. Psychopharmacology 146, 348–361 (1999). https://www.etymonline.com
 Luht, K., Tokko, T., Eensoo, D., Vaht, M. & Harro, J. Efficacy of intervention at traffic schools reducing impulsive action, and association with candidate gene variants. Acta Neuropsychiatrica 31, 159–166 (2019).
 Oreland, L., Nordquist, N., Hallman, J., Harro, J. & Nilsson, K. W. Environment and the serotonergic system. European Psychiatry 25, 304–306 (2010).
 Stanford, M. S. et al. Fifty years of the Barratt Impulsiveness Scale: An update and review. Personality and Individual Differences 47, 385–395 (2009).