Concurrent mental health and substance use disorders among Canadian adults during the COVID-19 pandemic: a population-based study

Introduction Concurrent disorders, defined here as co-occurring mental health disorders (MHD) and substance use disorders (SUD), pose challenges for treatment and public health. This study examines the prevalence and characteristics associated with MHD only, SUD only, and concurrent disorders among Canadians aged 15 and older during the COVID-19 pandemic. Methods We analyzed data from the 2022 Mental Health and Access to Care Survey (MHACS), a cross-sectional survey of Canadians aged 15 and older living in the 10 provinces (n = 9861). MHD and SUD were assessed using the WHO Composite International Diagnostic Interview. Respondents were classified into four groups: no disorder, MHD only, SUD only, and concurrent disorders. Multinomial logistic regression identified sociodemographic, health, and pandemic-related characteristics associated with these disorder categories, using survey weights and bootstrap methods. Results Among respondents, 1.6% had concurrent disorders, 12.2% had a MHD only, and 1.6% had a SUD only. Younger adults, especially those aged 20 to 24, and 2SLGBTQI+ individuals had elevated risk for concurrent disorders. Additional correlates included lower education, rural residence, weak sense of belonging, and functional impairment. Pandemic-related stressors—loneliness, financial hardship, and difficulty accessing care—were strongly associated with concurrent disorders. Conclusion This study highlights the prevalence and key correlates for MHD, SUD, and concurrent disorders among Canadian adults during the COVID-19 pandemic. Vulnerable populations include younger individuals, sexual and gender minorities, and those facing social isolation or unmet care needs. These findings underscore the importance of ensuring integrated, accessible mental health and substance use services in Canada’s postpandemic recovery.