Alcohol and marijuana use associated with lower GPA in college

Alcohol and marijuana use associated with lower GPA in college

U.S. college students who consume medium-to-high levels of alcohol and marijuana have a consistently lower GPA over two years, according to a new study.

Alcohol and marijuana are the two most abused substances in U.S. colleges. It might seem obvious that excessive consumption of these substances can be bad for students’ health, but what about the effect on their work? Previous studies have shown a link between consumption of alcohol and marijuana and rates of absences and drop-outs, but the but the link between consumption and academic performance was not known.

Shashwath Meda from Hartford Hospital’s Institute of Living, USA, and colleagues addressed this question, examining the association between college students’ alcohol and marijuana consumption and their grade point average (GPA) in each semester. They used self-reported data from the Brain and Alcohol Research with College Students study, which tracked 1,142 students for two years after they began college, and clustered students into groups of low users or medium-to-high users of alcohol or both substances.

Despite no differences between the groups in pre-college SAT scores, the researchers found that students who were medium-to-high users of both substances did worse academically: they not only had a lower predicted GPA on average by the end of the first semester, but continued to achieve lower GPAs throughout the two years of the study.

“Doing a lot of both drugs had a significant impact in terms of lower grades in our study,” said senior author Godfrey Pearlson.

However, there was some hope for students who decreased their substance use over time: their GPA increased relative to that of their peers who remained consistent in their drug use patterns. This suggests that heavy substance use was not associated with a long-term lowered GPA in these students. And interestingly, while students who consumed alcohol but little marijuana started out with a lower predicted GPA, like heavy users of both substances, these students’ GPAs had caught up with those of low users of the substances by the end of the two years.

The study results only indicate an association between substance use and lower GPA scores rather than demonstrating causation, and the results rely on self-reported data on consumption. Nonetheless, the research adds to the understanding of how alcohol and marijuana use may play a role in academic performance.

Research Article: Meda SA, Gueorguieva RV, Pittman B, Rosen RR, Aslanzadeh F, Tennen H, et al. (2017) Longitudinal influence of alcohol and marijuana use on academic performance in college students. PLoS ONE 12(3): e0172213. doi:10.1371/journal.pone.0172213

Image Credit: aeroSoul, Flickr


Beth works at PLOS as Journal Media Manager. She read Natural Sciences, specializing in Pathology, at the University of Cambridge before joining PLOS in 2013. She feels fortunate to be able to read and write about the exciting new research published by PLOS.

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