Changes in substance use and mental health in two hospital-based addiction treatment programs over the course of recreational cannabis legalization in Canada
Costello, J., MacKillop, J., Cooper, A., Sousa, S., Brasch, J., & Chorny, Y.
This study looked at how legalizing non-medical cannabis in Canada affected the health and well-being of people who have substance use disorder (SUD) or cannabis use disorder (CD). The researchers looked at two groups of people who were starting treatment for SUD or CD to see if legalizing cannabis changed their cannabis use, their symptoms of CD, and their readiness to change. They also looked at changes in their use of other substances like tobacco, alcohol, and other drugs. Two studies (Studies One and Two) analyzed changes in cannabis use trends among individuals who entered treatment for substance use disorder or cannabis use disorder after non-medical cannabis legalization, using interrupted time series (ITS) study design. Two additional studies (Studies Three and Four) explored associations between cannabis use, other substance use, and common psychiatric symptoms, using logistic regression and latent profile analysis (LPA). The same two clinical populations were used for all four studies, with Study One and Three examining inpatient individuals, and Study Two and Four examining outpatient individuals.
The study found that legalizing non-medical cannabis did not cause significant increases in cannabis use or CD symptom severity among the two groups of people with SUD. Legalization also did not decrease their readiness to quit using cannabis. Additionally, there were no major changes in tobacco, alcohol, or other drug use after legalization. The researchers also found that different people in the sample had different levels of CD and psychiatric symptoms, and they suggest it is important to consider these factors when making cannabis policies and monitoring the effects of legalization.
Publications:
Costello, M. J., Britton, E., Cooper, A., Sousa, S., Li, Y., Chorny, Y., Brasch, J., & MacKillop, J. (2023). Examining the potential impact of legalizing nonmedical cannabis in Canada: An interrupted time series study of cannabis use in two substance use disorder treatment settings [Manuscript submitted for publication].
Costello, M. J., Cooper, A., Sousa, S., Chorny, Y., Brasch, J., & MacKillop, J. (2023). Exploring the associations between cannabis use, other substance use and common psychiatric symptoms [Manuscript in preparation].