alcohol and marijuana

Two years of data from over 1000 college students has revealed a strong association between low GPAs and students who simultaneously use alcohol and marijuana.


The consumption of alcohol and marijuana during college has become an accepted part of the ‘college experience’. The irony here is obvious- the downtime of the years we’re supposed to spend achieving educational enlightenment are awash with brain-cell-killing pursuits.

It has been shown that substance use compromises cognitive ability. Mainstream knowledge associates consistent alcohol and marijuana use with laziness, memory loss, impaired decision-making, and as “gateway” drugs- all of which is backed up by reputable research. Despite students knowing that they’re jeopardizing the critical skills necessary to succeed, they continue to enthusiastically pursue a “buzz”.

The prevalence of this contradictory substance use is alarming: 80% of students drink alcohol, half of them binge drink, over half of students have used marijuana, and 58% of students report using them simultaneously. Research into the effects of this practice is surprisingly scant, although nearly 2 out of 3 students report indulging in the behavior.

A new study published in PLOS One, by Shashwath et al., is among the first to investigate the effects of using alcohol and marijuana at the same time. Researchers examined data from the Brain and Alcohol Research in College Students study, measuring 1142 freshman’s monthly use of alcohol and marijuana over two years. Researchers grouped students into three groups: no/low users of either substance, medium-high alcohol & no/low marijuana, and medium-high users of both.

Interestingly, pre-college SAT scores showed no significant difference between sober students and their peers. However, the sober group matched their predicted GPAs and remained consistently successful. The group reporting ‘drinking only’ initially scored lower, but over time showed no significant difference from their sober friends. Students using both alcohol and marijuana scored lower at the outset and throughout their two subsequent years of study. The good news is that students who curtailed their substance use showed an increasing GPA over time.

A fascinating accidental finding of the study found almost no students reported a behavior that paired minimum alcohol and heavy marijuana use. This posed a challenge to parse out marijuana’s effect on academic performance. Also, heavy users of both substances maintained their initial GPA throughout the two years, indicating a potential lifestyle compensation or biological/genetic tolerance.

This study is powerful in its implications for any student hoping to “party hard” and keep a competitive GPA. However, it’s important to remember that this study is not measuring causation, only association between drug use and academic performance. The true cause of a lower GPA may be something deeper, like mental illness, to which they substance use would just be a coping mechanism.


Written By: Soleil Grisé, HBSc

Facebook Comments