Impulsivity, neural deficits, and the addictions: the "oops" factor in relapse

Impulsive behaviors are observed in a wide range of psychiatric disorders, including substance use, bipolar, attention-deficit hyperactivity, antisocial and borderline personality, gambling, and eating disorders. The shared phenotype of impulsivity is thought to significantly contribute to both the etiology and perpetuation of these disorders. In this review, we focus upon the relevance of impulsivity to the addictive disorders, particularly substance use disorders. First, the literature supporting the presence of impulsive behaviors prior to the onset of drug use and addiction is discussed. The relevance of impulsivity to relapse is then presented, with a focus on three distinct neurocognitive constructs: automaticity, response inhibition, and decision making. Automaticity is a quickly occurring relapse process resulting from the learned habits induced by persistent drug use. Addicted persons with response inhibition deficits are unable to suppress these previously reinforced behaviors. Decision-making deficits contribute to relapse through a poorly considered assessment of the consequences of drug use. The brain regions associated with each model of impulsive behavior are described, and relevant neurobiologic disruptions in addicted subjects are discussed in the context of their specific neurocognitive deficit(s). Descriptive confusions in the terminology and confounds inherent in the study of impulsivity are described. Empirical investigations documenting the hypothesized relationship between specific deficits in impulsive behaviors, coupled with their neurobiological correlates, and relapse should be the focus of future studies.