The effects of early life stress on impulsivity

Abstract

Elevated impulsivity is a symptom shared by various psychiatric disorders such as substance use disorder, bipolar disorder, and attention-deficit/hyperactivity disorder. However, impulsivity is not a unitary construct and impulsive behaviors fall into two subcategories: impulsive action and impulsive choice. Impulsive choice refers to the tendency to prefer immediate, small rewards over delayed, large rewards, whereas impulsive action involves difficulty inhibiting rash, premature, or mistimed behaviors. These behaviors are mediated by the mesocorticolimbic dopamine (DA) system, which consists of projections from the ventral tegmental area to the nucleus accumbens and prefrontal cortex. Early life stress (ELS) alters both impulsive choice and impulsive action in rodents. ELS also changes DA receptor expression, transmission, and activity within the mesocorticolimbic system. This review integrates the dopamine, impulsivity, and ELS literature to provide evidence that ELS alters impulsivity via inducing changes in the mesocorticolimbic DA system. Understanding how ELS affects brain circuits associated with impulsivity can help advance treatments aimed towards reducing impulsivity symptoms in a variety of psychiatric disorders.

Keywords: Cognition; Nucleus accumbens; Prefrontal cortex; Sex differences; Stress.

Fig. 1.

A schematic showing how the NAc core and shell regulate aspects of impulsivity. Changes in the dopaminergic system that increase DA tone in the shell promote impulsive action. In contrast, changes in the dopaminergic system that decrease DA signaling in the core promote impulsive choice. DA, dopamine; D1 receptor, dopamine 1 receptor; D2 receptor, dopamine 2 receptor; DAT, dopamine transporter.