Frequent Marijuana Use and Cognitive Flexibility in Young Adult College Students

Author(s): Anita Cservenka


Background: Frequent marijuana (MJ) use has been associated with deficits in executive functioning (EF), but few studies have examined the contribution of recent and lifetime MJ use to the magnitude of EF impairment in young adults.

Purpose of current study: We examined cognitive flexibility in 18- 22 year old college students, who were heavy marijuana users (MJ+) or healthy controls (HC). We hypothesized MJ+ would have poorer cognitive flexibility compared to HC, which would be related to earlier age at first MJ use, and greater past 30-day and lifetime MJ use.

Methods: 28 MJ+ (68% male) using MJ ≥ 5 times/week and 33 HC (55% male) using MJ ≤ once/month in the past year completed the Modified-Wisconsin Card Sorting Test, and an EF-composite score was calculated based on categories correct and perseverative errors t-scores.

Results: MJ+ had a significantly lower EF-composite score compared to HC (t(59)=2.50, p=0.02), and this was related to greater past 30-day MJ use (r (26)=-0.38, p=0.049). Conclusion: Impaired cognitive flexibility in MJ+ and greater recent MJ use may contribute to the maintenance of MJ use, making it difficult to choose alternatives to reduce MJ use.

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