Research suggests potential targets for prevention and early identification of psychotic disorders

A new study by the Centre for Addiction and Mental Health (CAMH), titled "Mental health service use before first diagnosis of a psychotic disorder" and published in JAMA Psychiatry, found that nearly 75% of young Ontarians with a psychotic disorder had at least one mental health service visit within the three years prior to their first diagnosis of the disorder.

The retrospective cohort study—one of the largest of its kind—suggests that youth with a psychotic disorder are nearly four times as likely to have a previous mental health-related hospital admission, twice as likely to have a mental health-related emergency department visit, and more likely to have a past diagnosis of substance use disorder compared to youth diagnosed with a mood disorder.

"Our findings suggest that these factors—prior mental health-related hospital admissions and emergency department visits, and prior diagnosis of substance use disorder—may indicate increased risk for a psychotic disorder," says Dr. Nicole Kozloff, Co-Director of the Slaight Family Centre for Youth in Transition at CAMH. "These results are remarkably consistent with other jurisdictions outside Canada, and should guide further research into detecting and intervening earlier in the course of psychotic illness."

As part of the study, the researchers used information held by ICES on health service use and other linked data to examine previous mental health use in Ontarians aged 15-29 years who were later diagnosed with a psychotic disorder between April 1, 2012 and March 31, 2018. The team identified more than 10,000 individuals with a first diagnosis of psychotic disorder and matched them with individuals who were diagnosed with a mood disorder.

"Those at risk for psychosis are 'hiding in plain sight,'" says Dr. Aristotle Voineskos, Vice President, Research at CAMH and Director of the Campbell Family Mental Health Research Institute. "These data provide a very different picture of who is at risk for psychosis, and also suggest the opportunity moving forward to examine whether effective treatment for prior conditions may change the risk for psychosis."

The early findings from this research inspired the launch of the Toronto Adolescent & Youth (TAY) Cohort Study at CAMH. This five-year study is tracking 1,500 children and youth presenting for mental health services, examining their biology, education and cognition, social factors, and service use patterns. The goal is to increase understanding of who is at risk for psychosis and, most importantly, how to mitigate that risk via earlier intervention.