Neighbourhood risk factors and spatiotemporal trends for overdoses following cannabis legalization and pandemic restrictions in Toronto, Canada

Drug & opioid overdoses in Toronto, Canada, have risen substantially in recent years. To explore possible causes, we spatially analyze associations between overdose incidence data over 2019-2022 and select socioeconomic & built-environment variables among Toronto neighbourhoods. Using spatiotemporal analysis, we also assess average area trends and local hotspots before/after two major events: Canada's 2018 legalization of cannabis (2017-2020) and COVID-19 pandemic lockdowns (2019-2022). Previous discussions frame cannabis as a possible alternative to more dangerous drugs, while pandemic lockdowns were likely to reduce mental health and access to care. We find 1) overdose incidence shows positive association with household/neighbourhood instability and percent building coverage, 2) notable overdose increases in Toronto's suburban neighbourhoods, and 3) rising mean-area overdose rates, despite cannabis legalization. Potentially outsized effects of high-potency illicit opioids and pandemic lockdowns may influence these results. Policymakers should monitor post-lockdown overdose trends and explore harm reduction approaches and improved housing options as policy responses to reduce impacts from Toronto's ongoing drug crisis, especially in areas outside the downtown that have rising overdose rates.