After legalization, average impairment did not significantly increase in this…

We investigated the relationship between the use of cannabis available after legalization and adverse effects in individuals diagnosed with Cannabis Use Disorder (CUD). We utilized an existing longitudinal study of high-risk individuals (364 high-risk participants in treatment for substance use disorder (SUD) in adolescence and 407 of their siblings) that were assessed twice before January 2014 (when recreational cannabis dispensaries first opened in Colorado) and once after 2014. We hypothesized that participants who met DSM criteria for CUD after 2014, when high THC concentration cannabis products became more readily available, would demonstrate more adverse physical and psychological symptoms and endorse more DSM criteria compared to those meeting DSM criteria for CUD before 2014. In general, we did not find evidence for significant mean differences in impairment after 2014. Contrary to expectation, we found that high-risk participants with CUD endorsed significantly more DSM criteria before 2014 than after 2014. Exploratory trajectory analyses identified a small subgroup of high-risk participants (21.5%) and siblings (20.1%) exhibiting an increase in the number of CUD criteria endorsed who experienced significantly more psychological and physical symptoms after 2014. It is possible that increased THC potency products have had less effect on individuals in this high-risk sample, many of whom have been daily users for many years and have substantial tolerance for THC. Similar studies of individuals who use cannabis recreationally and less frequently are necessary.