A study examining trends in adult cannabis consumption in Canada following legalisation in 2018 has found that although overall frequency of use increased slightly, the number of individuals whose use was designated problematic decreased marginally.
Published in the journal JAMA Network Open, the research analysed data from 1,428 participants who provided information about their cannabis consumption every six months over a five-year period beginning in October 2018, when legal sales commenced.
The researchers sought to understand how adult-use cannabis legalisation affected consumption habits, particularly regarding frequency of use, problematic usage patterns, and preferred consumption methods.
“Primary outcomes were cannabis use frequency and cannabis misuse, assessed using Cannabis Use Disorder Identification Test – Revised (CUDIT-R) score. Prelegalization cannabis use frequency, age, and sex were examined as moderators. Secondary outcomes included changes in cannabis product preferences over time,” the study explained.
The data revealed that cannabis use frequency increased by 0.35% annually, equating to 1.75% over the five-year study period. Equally minor was the decrease in cases of problematic cannabis use, as defined by the CUDIT-R assessment (Cannabis Use Disorder Identification Test – Revised). This is measured on a scale of 32 points, and the reduction shown was 0.4 over the five-year period.
“We note that for both outcomes, while changes were statistically significant, it is debatable whether these changes were clinically significant, particularly in the case of CUDIT-R, which decreased by only 0.4 points on a scale of 32 over 5 years,” the study authors wrote.
The largest declines in frequency of use were in the group that used cannabis the most frequently pre-legalisation. The sharpest decline in cases of cannabis use disorder came during the COVID-19 pandemic, particularly among individuals who were using cannabis weekly pre-legalisation. Researchers suggest that this demonstrates a cannabis consuming population that was maturing and learning to use cannabis in a more responsible way.
The results suggest that the legalisation of cannabis in Canada in 2018 had mixed effects on public health, while the decline in cases of cannabis misuse disorder was seen as a positive outcome, the increase in frequency of use was deemed a negative outcome.
“This cohort study found a small increase in mean cannabis use frequency and a small decrease in mean cannabis misuse in the 5 years following recreational cannabis legalization in a community-based nonclinical cohort of adults in Canada. These changes were moderated by prelegalization cannabis use, with individuals with more frequent prelegalization consumption exhibiting the largest decreases in both outcomes. The apparent discrepancy between increasing cannabis use and decreasing cannabis misuse may have been driven by younger cannabis users, who typically transition from problematic to nonproblematic use as they age. This study also found that cannabis users’ product preferences evolved over the course of legalization away from dried flower and toward noncombustion products,” the study concluded.
