The odds of having both a substance use disorder and a mood or anxiety disorder nearly doubled over a 10-year period in Canada, a new McMaster study has found. The increase in co-occurring disorders was observed despite substance use disorders alone becoming less common.
The findings, published in Psychiatry Research on Aug. 17, represent the most up-to-date national picture of co-occurring mood, anxiety, or substance use disorders in Canada, using nationally representative data from Statistics Canada.
“Mental health challenges in Canada are becoming increasingly complex,” says lead author Jillian Halladay, an assistant professor with McMaster’s School of Nursing and youth substance use research lead with the Peter Boris Centre for Addictions Research and Offord Centre for Child studies. “Many people are not dealing with just one condition.”
“We’re seeing growing numbers of Canadians experiencing both substance use disorders and mood or anxiety disorders at the same time, and those individuals often face the greatest challenges getting the support they need.”
To conduct the study, researchers analyzed nationally representative survey data from Statistics Canada of nearly 35,000 Canadians aged 15 and older, collected in 2012 and 2022. Using a standardized diagnostic interview, they assessed mood, anxiety, and substance use disorders and examined how their prevalence and co-occurrence changed over the decade.
Researchers found:
- One in six Canadians experienced a mood, anxiety or substance use disorder in 2022, while nearly half of those with a substance use disorder also had a co-occurring mood or anxiety disorder.
- Compared with 2012, the odds of mood and anxiety disorders were 2.5 times higher and the odds of concurrent disorders were nearly double.
- Those with concurrent disorders reported greater distress, suicidality, and unmet care needs. Interestingly, researchers found the odds of having a substance use disorder alone were 40 per cent lower in 2022.
- Nearly one in three Canadians aged 15 to 24 had a mood, anxiety, or substance use disorder in 2022. Youth also had almost three times the odds of experiencing concurrent disorders than adults. Females were also more likely than males to experience mood and anxiety disorders and co-occurring mood/anxiety conditions.
The study didn’t set out to find the cause of the increase in co-occurring disorders, however, researchers say it’s likely a complex combination of long-term social changes, the pandemic and broader shifts in mental health and substance use patterns.
“This work highlights the urgent need for integrated mental health and substance use services, particularly for youth and females, who are disproportionately affected,” Halladay says.
“Our findings highlight the need for a system that treats the whole person. Many Canadians experiencing substance use disorders are also struggling with anxiety or depression, yet care is often delivered separately.”
The study was supported in part by a Canadian Institutes of Health Research Health System Impact Embedded Early Career Researcher Award. Researchers with the Peter Boris Centre for Addictions Research, Offord Centre for Child Studies, and School of Nursing, as well as the Matilda Centre for Research on Mental Health and Substance Use at the University of Sydney contributed to the study.