Experimentation versus progression in adolescent drug use: A test of an emerging neurobehavioral imbalance model

Abstract

Based on an emerging neuroscience model of addiction, this study examines how an imbalance between two neurobehavioral systems (reward motivation and executive control) can distinguish between early adolescent progressive drug use and mere experimentation with drugs. Data from four annual assessments of a community cohort (N = 382) of 11- to 13-year-olds were analyzed to model heterogeneity in patterns of early drug use. Baseline assessments of working memory (an indicator of the functional integrity of the executive control system) and three dimensions of impulsivity (characterizing the balance between reward seeking and executive control systems) were used to predict heterogeneous latent classes of drug use trajectories from early to midadolescence. Findings revealed that an imbalance resulting from weak executive control and heightened reward seeking was predictive of early progression in drug use, while heightened reward seeking balanced by a strong control system was predictive of occasional experimentation only. Implications of these results are discussed in terms of preventive interventions that can target underlying weaknesses in executive control during younger years, and potentially enable at-risk adolescents to exercise greater self-restraint in the context of rewarding drug-related cues.

Figure 1

Estimated recent drug use curves from the 2-class latent growth class analysis solution. Note. Class 1 = “Progressors”; Class 2 = “Low/Non-users”

Figure 2

Item response probabilities for recent (past 30 days) drug use: (a). Class-specific probabilities of at least one drug used in the past 30 days; (b). Class-specific probabilities of having used more than one drug in past 30 days

Figure 3

Pre-existing weaknesses in working memory predict latent classes of adolescent drug use trajectories Note. *p<.05, **p<.01, ***p<.001. WM = Working Memory, AWT = Acting Without Thinking, DD = Delay Discounting. ^cThe trajectory class variable represents latent probabilities of belonging to the “progressors” class as compared to the “low/non-users” class. Regression coefficients on significant paths represent the effects of background variables on being in the “progressors” class vs. the “low/non-users” class. Higher scores on AWT (Odds Ratio = 23.8, p < 0.001), and DD (Odds ratio = 1.01, p < 0.05) were associated with greater likelihood of being in the “progressors” than the “low/non-users” class. The mediated effect of WM suggests that high WM at baseline was inversely related to AWT and DD, resulting in a net lower likelihood of belonging to the “progressors” than the “low/non-users” class. There was no left over direct effect of WM on trajectory class membership. The effect of age, sex, and socio-economic background was covaried out.