Adolescent brain maturation and smoking: what we know and where we're headed

Abstract

Smoking is a leading cause of mortality and morbidity worldwide. Smoking initiation often occurs during adolescence. This paper reviews and synthesizes adolescent development and nicotine dependence literatures to provide an account of adolescent smoking from onset to compulsive use. We extend neurobiological models of adolescent risk-taking, that focus on the interplay between incentive processing and cognitive control brain systems, through incorporating psychosocial and contextual factors specific to smoking, to suggest that adolescents are more vulnerable than adults to cigarette use generally, but that individual differences exist placing some adolescents at increased risk for smoking. Upon smoking, adolescents are more likely to continue smoking due to the increased positive effects induced by nicotine during this period. Continued use during adolescence, may be best understood as reflecting drug-related changes to neural systems underlying incentive processing and cognitive control, resulting in decision-making that is biased towards continued smoking. Persistent changes following nicotine exposure that may underlie continued dependence are described. We highlight ways that interventions may benefit from a consideration of cognitive-neuroscience findings.

Keywords: Adolescence; Cognitive control; Incentive processing; Nicotine dependence.

Figure 1. A schematic illustration of the processes leading to smoking initiation according to our model

The normative increase in impulsivity during adolescence and contexts containing positive smoking norms act as risk factors for the development of positive smoking expectancies (section 3.6). Positive smoking expectancies facilitate the generation of incentive motivation towards smoking when adolescents encounter a cigarette. Encountering a cigarette is more likely in contexts in which there is a high availability of cigarettes. Furthermore, the incentive motivation experienced by adolescents is stronger than that experienced by other developmental groups due to normative brain development (section 3.4), although there are also important individual differences (section 3.6). At this point, there are many potential pathways that may lead an adolescent to act on the impulse to smoke the cigarette encountered. We present these paths to demonstrate that processes beyond the inhibition of impulsive responses are important to consider in models of adolescent risk-taking (see section 3.5). Two potential pathways are illustrated in this figure. In the first pathway (1), adolescents simply act on the initial impulse and smoke the cigarette. In the second pathway (2), the initial impulse is inhibited and deliberative decision-making is engaged. The inhibition of the initial impulse may be more difficult during adolescence relative to other age groups due to the continued maturation of cognitive control and the heightened incentive motivation occurring during this period. Furthermore, adolescents may lack the motivation to inhibit the initial impulse to smoke. Once deliberative decision-making is engaged, adolescent-specific content of the decision-making process (see section 3.5), leads the adolescent to act in line with their original impulse and to accept the cigarette.