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  • A Systematic Review and Met...
    Strickland, Justin C.; Lee, Dustin C.; Vandrey, Ryan; Johnson, Matthew W.

    Experimental and clinical psychopharmacology, 12/2021, Volume: 29, Issue: 6
    Journal Article

    Delay discounting reflects the systematic reduction in the value of a consequence by delay to delivery. Theoretical and empirical work suggests that delay discounting is a key behavioral mechanism underlying substance use disorder. Existing work on cannabis use, however, is mixed with many studies reporting null results. The purpose of this review was to provide an in-depth assessment of the association between delay discounting and cannabis use. We conducted metaregression analyses to determine the omnibus correlation between delay discounting and cannabis use, and to evaluate task-based and sample-based moderators. Studies included evaluated an association between delay discounting and cannabis quantity-frequency or severity measures in human participants (27 studies, 61 effect sizes, 24,782 participants). A robust variance estimation method was used to account for dependence among effect sizes. A significant, but small, omnibus effect was observed (r = .082) in which greater cannabis use frequency or severity was associated with greater discounting. Incentive structure and outcome type were each significant moderators in a multiple moderator model such that incentivized tasks correlated with severity measures showed stronger associations (r = .234) than hypothetical tasks correlated with quantity-frequency measures (r = .029). Comparisons to historic effect size data supported the hypothesis that, at present, the relationship between cannabis use and delay discounting appears empirically smaller than for other substances. Future work should explore theoretical rationales explaining this modest relationship involving cannabis use and delay discounting, such as reflecting the smaller magnitude of perceived long-term clinical outcomes associated with cannabis compared to other substances. Public Health Significance How much individuals devalue future consequences (i.e., delay discounting) has been extensively studied for its relevance to substance use disorder. Fewer studies have evaluated associations with cannabis use and those that exist present mixed evidence. This meta-analysis summarizes this literature and finds that the association between delay discounting and cannabis use is, on average, small and is greater when evaluating severity of cannabis use with discounting assessed by incentivized tasks as compared to when evaluating use rates with discounting assessed by hypothetical tasks.