NIDA International SPR Poster Session: Do Marijuana Use and Externalizing Behaviours Mediate the Association between Academic Aptitude and Academic Performance?

This abstract was presented at the 2018 Society for Prevention Research Annual Meeting which was held May 29 – June 1, 2018 in Washington, DC, US.

Clea M. B. Sturgess University of Victoria

Bonnie Leadbeater University of Victoria; Gabriel "Joey" Merrin University of Illinois at Urbana-Champaign

Introduction: Past research has found that externalizing behaviours and marijuana use negatively affect academic performance. However, precursors to these pathways are not well understood. Early evidence of academic aptitude is an important predictor of academic performance in high school. Most youth who perform well at early ages tend to continue to perform well and most of those who do not tend to continue to perform poorly throughout their academic careers. However, this is not true for everyone. It is important to understand the factors that may impact students’ academic performance, and how early academic aptitude can influence risk factors that impact later academic performance. This study examines the role that marijuana use and externalizing behaviours play in the association between early academic aptitude and later academic performance. 

Methods: The study uses six waves of data from the Victoria Healthy Youth Survey (V-HYS), a 10-year prospective longitudinal study. A community-based sample of youth (N= 662; 48% male; ages 12 to 18) were surveyed biannually from 2003 (W1) to 2014 (W6). Frequency of marijuana use over the past year was assessed at each time point. To assess academic aptitude, participants’ British Columbia Foundation Skills Assessment (FSA) percentile scores in numeracy, reading, and writing were measured in grades 7 and 10. Academic performance was assessed using participants’ grade 12 English and Math course percentage grades. Path analysis was used to examine the extent to which adolescent levels of marijuana use and externalizing behaviours mediated the association between early academic aptitude and later academic performance. All models controlled for SES, age, and sex. 

Results: Academic Aptitude was positively associated with grade 12 English (ß = .44, SE = .04, p < .001), grade 12 Math (ß = .48, SE = .05, p < .001), and negatively associated with externalizing (ß = -.22, SE = .04, p < .001) and marijuana use (ß = -.12, SE = .04, p < .01). Marijuana use was significantly negatively associated with grade 12 English (ß = -.11, SE = .04, p = .01) but not with grade 12 Math (ß = -.12, SE = .07, p = .08). Externalizing was not significantly associated with grade 12 English (ß = -.05, SE = .04, p = .20) nor with grade 12 Math (ß = .01, SE = .06, p = .89). The indirect effect of marijuana use was significant (ß = .01, SE = .00, p = .05). 

Conclusions: Marijuana use mediates the association between early academic aptitude and later academic performance, indicating the importance of early prevention and intervention. Early academic aptitude is also an indicator of who may be at risk for marijuana use and externalizing.