Mental health disorders overwhelmingly common in people experiencing homelessness

Health-care professionals who work with people experiencing homelessness know many of the people may also be living with a mental health disorder. University of Calgary researchers wanted to better understand how often these two things are connected, and what they found surprised them.

We found 66-to-75 per cent of people who are experiencing homelessness have an underlying mental health condition. We have always known that mental health disorders are overrepresented among people experiencing homelessness, but we didn't have a clear understanding of how many people are affected."

Dr. Dallas Seitz, MD, PhD, psychiatrist and clinician-researcher at the Cumming School of Medicine, and senior author of the paper

Seitz says the researchers reviewed studies from 1980 to 2021 that investigated the prevalence of mental health disorders among people experiencing homelessness aged 18 and older. Findings reveal males experienced a significantly higher lifetime prevalence of mental health disorder at 86 per cent, compared to females at 69 per cent. Specific mental health disorders fell into five categories with substance use disorder being the most prevalent (44 per cent) followed by antisocial personality disorder, major depression, schizophrenia, and bipolar disorder.

"When you really look at the data you can see the concentration of illness in a certain population and these numbers are staggering. One-in-10 have a serious mental illness," says Seitz. "Psychotic disorders alone affect one per cent of the general population. That number is eight times higher for those who experience homelessness."

Researchers say that during the time-period of the studies they reviewed the number of people experiencing mental illness increased among studies published more recently. Seitz says mental health supports should be implemented together with housing and financial supports.

"Now that we understand the extent and close connection of mental health, addictions and homelessness we need to create targeted, specific supports that are evidence-based," says Dr. Rebecca Barry, PhD, first author on the study. "In our paper we couldn't determine whether the mental health disorder came first or was a consequence of homelessness, however there's likely a bi-directional relationship and we need to consider both to address the need." 

The findings are published in JAMA Psychiatry. Seitz says the paper is the foundation of a larger project funded by the Calgary Health Foundation. He is evaluating the prevalence of mental health disorders and homelessness in Calgary to help determine what the specific needs are here. Seitz is working with population health data and data from the Calgary Homeless Foundation.

"One way forward is to look at ways to link health and housing data together which would allow service providers and researchers to better understand the needs of this population," says Seitz.

The researchers concluded that there is a vital need for integrated interventions, as well as gender specific approaches to address homelessness and the health disparities that both cause it and result from it.