COVID-19’s impact on cannabis use: Can we trust retrospective cross-sectional data?

Abstract

Background: Emergent research suggests there has been an increase in cannabis use levels during the COVID-19 pandemic; however, several gaps remain. It is unclear what impact the pandemic has had on the frequency vs. quantity of cannabis use. Additionally, research has not focused on emerging adults, a population often more likely to use cannabis. Moreover, as existing studies are cross-sectional and retrospective, it is not clear whether participant reports of increasing cannabis use during COVID-19 are accurate. We sought to fill these gaps to provide further information about the impact of COVID-19 on cannabis use and the accuracy of related retrospective self-reports. Design and Methods: Seventy emerging adults in an ongoing longitudinal study on alcohol and cannabis users completed surveys on COVID-19 and substance use between March 23rd-June 5th. Their substance use four months earlier was extracted from the existing dataset. Results: 54% of participants reported an increase in cannabis use frequency during the pandemic, while 39% reported an increase in cannabis quantity. An examination of objective change scores indicated 50% of participants actually increased their cannabis use frequency during the pandemic, while 32% actually increased their cannabis quantity. A comparison of retrospective subjective change with longitudinal objective change scores indicated participants were relatively accurate in their retrospective reports of change in cannabis use frequency but were relatively inaccurate in their retrospective reports of change in cannabis use quantity. Discussion: The COVID-19 pandemic appears to increase cannabis use frequency in the slight majority of cannabis using emerging adults. Our results suggest that retrospective cross-sectional reports may be a reasonable proxy for COVID-19 related cannabis use change in the case of cannabis use frequency. But our results question their use for determining how the pandemic is impacting cannabis use quantity. Importantly, our results suggest the COVID-19 pandemic poses health threats that extend beyond the virus itself. It is essential that public health efforts address the increasing frequency of cannabis use in emerging adult users.