Early Progression Vs. Experimentation with Drugs and Risk for Dependence in Young Adulthood

Introduction: Early initiation of substance use during adolescence is linked to higher risk of developing substance use disorders (SUD) which cost the nation over $181 billion per year in lost productivity, injuries, and death (ONDCP, 2004). However, not all adolescents who experiment with drugs at a young age go on to develop SUD. Indeed, there are distinct early onset drug use patterns (e.g., occasional experimentation vs. consistent and progressive use) that are differentially related to risk for later SUD (Flory et al., 2004). Here, we seek to (a) distinguish between distinct trajectories of early onset drug use as they relate to pre-existing weaknesses in working memory (WM) and associated impulsivity dimensions, and (b) examine their association with the emergence of SUD during young adulthood.

Methods: Data from four annual assessments of a community sample of 382 adolescents (Mean baseline age = 12.6±0.89 yrs; 52% female; 56% non-Hispanic White) were analyzed using Latent Growth Class Analysis to model latent drug use trajectory classes.

Results: We found evidence for two distinct drug use trajectory classes- (1) ‘Low-users’ comprising of ‘abstainers’ (60%; who did not engage in any drug use) and ‘experimenters’ (10%; who occasionally experimented with drugs with no consistent pattern of use); and (2) Progressors (30%; who had higher baseline drug use scores, with persistent and increasing use of multiple drugs from early-mid adolescence). Adolescents with weak WM and associated impulsivity dimensions of “acting-without-thinking” and “delay discounting” were at greater risk for being in the progressor class as compared to the experimenter/abstainer class, B(SE)=0.26 (0.12), p<0.05. Experimenters were non-distinguishable from the abstainers in terms of the preceding risk factors of WM and impulsivity. Final follow-up at ages 18-22 revealed that early progressors were at significantly greater risk for developing alcohol use dependence, B(SE)=0.21 (0.10), p<0.05, as compared to abstainers. Early experimenters were not at elevated risk for developing symptoms of alcohol dependence as compared to abstainers, B(SE)=0.12 (0.25), p=0.64. Individual differences in impulsivity assessed during early adolescence predicted distinct patterns of drug use from early-mid adolescence, which in turn predicted dependence in young adulthood.

Conclusions: Findings suggest that not all forms of early onset drug use are linked to later SUD. Early indicators of risk such as weak WM and associated impulsivity can serve as reliable predictors of who is most vulnerable to problematic forms of use. Furthermore, the relative malleability of these risk factors (Jaeggi et al., 2011) provides a promising new avenue for intervening preventatively at a young age.