A short trial links reduced cannabis use to better driving and memory

AIMS: Interventions for cannabis use disorder often reduce the frequency and quantity of use, but rarely achieve sustained abstinence. It remains unclear whether reductions in use (rather than sustained abstinence) result in meaningful improvements in functioning. This study evaluated whether cannabis reductions among individuals with heavy use were associated with improvements in functional outcomes. DESIGN: Randomized controlled trial with ecological momentary assessment (EMA) and repeated daily biological verification of cannabis use. METHODS: Fifty-nine individuals were randomized to a mobile contingency management (mCM) intervention or a yoked control condition. Participants completed 2 weeks of EMA during a baseline ad lib cannabis use period, followed by a 6-week reduction period. Participants completed EMA assessments multiple times per day and were prompted to complete videotaped saliva cannabis testing 2-3 times daily. RESULTS: Group × time interactions indicated that participants randomly assigned to the mCM condition demonstrated significant functional improvements in drugged driving and working memory. The results for positive and negative affect and pain were less clear, and there was no detected change in physical activity. CONCLUSION: These results suggest that among individuals with heavy cannabis use, significantly reducing, but not abstaining from, cannabis was associated with decreased drugged driving and improved working memory; however, more research is needed, as the relatively short duration of the study may have limited our ability to detect longer-term functional changes. This study is among the first to demonstrate that significant reductions in cannabis use can result in significant short-term improvements in drugged driving and working memory.