Introduction: Impulsivity-A Transdiagnostic Trait

It is a pleasure to introduce this Special Report on impulsivity. Impulsivity, which can be defined as an overvaluation of short-term reward over long-term goals, is linked to other constructs, such as executive control and disinhibition. A transdiagnostic trait, impulsivity is a characteristic of many disorders that can appear to be rather distinct. Indeed, ADHD, gambling disorder, substance use disorders, bipolar affective disorder, borderline personality disorder, and Internet gaming disorder all share impulse dyscontrol as a prominent feature. The recent DSM-5 reclassification, with its emphasis on dimensionality, has further highlighted impulsivity, in part through the inclusion of 2 new diagnostic groupings: “obsessive-compulsive and related diorders,” which argues for a compulsive-impulsive spectrum, and “disruptive, impulse-control and conduct disorders.”

Several advances in our understanding of the biological basis of impulsivity informed this new nosology. Neuroimaging data suggest differential activation, gray matter density, and functional connectivity in cortical areas, such as the prefrontal cortex, the orbitofrontal cortex, the anterior cingulate cortex, and the amygdala. Motor task studies, such as stop signal reaction time, show impairment in prepotent response inhibition. And, neuropsychological tests, such as the Stroop test, show distractibility and delayed cognitive processing.

The topics selected for this special issue highlight the broad relevance of this symptom domain to clinical practice in psychiatry and beyond. Suicide and self-harm, for example, are often linked to impulsivity, but what do empirical evaluations of this link actually show? This association is discussed, and challenged, in an article by E. David Klonsky, PhD, and Alexis M. May, MA, in which a new model for assessing suicide risk is also advanced.

Parkinson disease is associated with significant morbidity, but iatrogenic impulse control disorders that can emerge during treatment add another layer of suffering and complexity. In the article by Jacob Taylor, MD, MPH, and Gregory Pontone, MD, the challenges of recognizing behaviors such as hypersexuality, gambling, and excessive buying in Parkinson disease are discussed, as are ways to address them while still managing the underlying condition.

Disorders of impulse control have also been called “behavioral addictions,” since they share features with substance use disorders. In his article, Luke Clark, MD, focuses on gambling disorder, now placed under DSM-5’s “substance-related and addictive disorders,” as the “quintessential” behavioral addiction, one with similarities to other behavioral addictions that are also discussed, such as “food addiction” and “Internet gaming disorder.”

Aggression can be a manifestation of illness that is of great concern to patients, their loved ones, and clinicians. This issue is addressed in an article by Sean Z. Kaliski, MB, BCh, PhD, that explores the potentially dangerous impulsivity-violence link across a broad range of conditions.

Finally, pharmacological treatments that target problematic impulses are discussed in this month’s CME activity. The message from the article by Jon E. Grant, JD, MD, MPH, and Samuel R. Chamberlain, MD, PhD, is that while impulsive behavior can be a distressing sign of pathology and while there is a clear need for more research and better treatments, some impulsive patients may benefit from available interventions.

I hope this Special Report contributes to your understanding of impulsivity and that it proves beneficial for your clinical practice.

Disclosures:

Dr Aboujaoude is Clinical Professor and Director of the OCD Clinic at the Stanford University School of Medicine, Stanford, Calif. He is the author and editor of several books, most recently, Mental Health in the Digital Age: Grave Dangers, Great Promise. He reports no conflicts of interest concerning the subject matter of this Special Report.