Working memory ability and early drug use progression as predictors of adolescent substance use disorders

Abstract

Aims: To test a neurobehavioral model of adolescent substance use disorder (SUD) resulting from an imbalance between a hyperactive reward motivation system and a hypoactive executive control system. Specifically, we tested (1) if early weakness in working memory (WM) and associated imbalance indicators of acting-without-thinking (AWT) and delay discounting (DD) predict SUD in late adolescence and (2) if early drug use progression mediates this relation.

Design: Five waves of longitudinal data collected annually from 2005 to 2010, with a final follow-up in 2012.

Setting and participants: Sample of 387 community adolescents (baseline ages 11-13 years) recruited from the Philadelphia, PA, USA area.

Measurements: WM was assessed at baseline using four different computerized tasks. AWT and DD were assessed at baseline using self-reports. Early drug use patterns were modeled using annual self-reports of recent drug use across the first four waves. Final outcome of SUD was assessed at last wave using self-reports matched to the DSM-5 criteria for three commonly used substances: alcohol, marijuana and tobacco.

Findings: Weakness in WM at baseline, associated with neurobehavioral imbalance indicators of AWT, B (SE) = -0.06 (0.02), P < 0.01 and DD, B (SE) = -7.30 (1.93), P < 0.01, was a significant predictor of SUD at final follow-up. WM predicted SUD both independent of early drug use, B (SE) = 0.08 (0.03), P < 0.05, and as mediated by early drug use progression, B (SE) = -0.06 (0.02), P < 0.01.

Conclusions: Adolescents with weak working memory have less control over impulsive urges, placing them at risk for later substance use disorder with some of the effects mediated by early drug use progression.

Keywords: Adolescence; delay discounting; early drug use; impulsivity; substance use disorders; working memory ability.

Conflict of interest statement

Declaration of Competing Interests: None.

© 2017 Society for the Study of Addiction.

Figures

Figure 1. Neurobehavioral imbalance model predicting SUD during adolescence

Note. SUD = Substance use disorder; WM = Working memory. We hypothesized that the imbalance captured by weakness in WM and associated impulsivity dimensions will predict later SUD both directly and as mediated by early drug use experiences.

Figure 2. Final SEM model showing effects of underlying weakness in executive control on SUD that is both direct and mediated by early drug use progression

Note. *p<.05, **p<.01, ***p<.001. WM=Working Memory, AWT=Acting Without Thinking, DD=Delay Discounting. “Early drug use experiences” was a nominal variable including abstainers, experimenters, and progressors; abstainers was omitted as the reference group. Only the “progressors” group was a significant predictor of SUD risk, and is shown in the model above. There was a significant residual correlation between alcohol and marijuana criterion scores. Model Fit: Chi Sq. (df=57) =69.24, p=0.13; RMSEA=0.02 (0.00, 0.04), CFI= 0.97, TLI= 0.96. The effect of age and gender was controlled for. The model explained 33% of variance in the latent SUD risk factor.