One in every two people who are homeless may have experienced a traumatic brain injury, according to new research out of the University of British Columbia.

The study, published this week in Lancet Public Health, is an overview of dozens of other studies which includes data about people who are homeless over the decades.

"The first step in addressing any problem, really, is recognizing that there is one," said Jacob Stubbs, one of the authors of the study and a PhD student in experimental medicine at UBC.

A few years ago, Stubbs was working on a study about the health of homeless and marginally-housed people in Vancouver's Downtown Eastside.

His supervisor Dr. William Panenka, an assistant professor with the university's neuropsychiatry program, noticed significant evidence of trauma on many of the MRI scans.

Those findings prompted this newest study, which is an analysis of data from 38 other studies that were all published between 1995 and 2018 from six high-income countries: Australia, Canada, Japan, South Korea, the UK, and the USA.

Stubbs was supervised on the project by Panenka — both are members of the the B.C. Mental Health and Addictions Research Institute — and the study was co-authored by researchers from other B.C. organizations.

The study found people who are homeless or in unstable housing have a disproportionately high prevalence of traumatic brain injury. Fifty-three per cent of those surveyed had a head injury at some point.

A quarter had experienced a moderate to severe injury.

Brain injuries are often associated with memory and concentration issues as well as mood and behavioural symptoms, Stubbs said.

"Healthcare workers and frontline workers should have an increased awareness of the burden of traumatic brain injuries in this population," he told CBC's Gloria Macarenko, the host of On The Coast.

For the general population, sports accidents and car accidents are among the most common cause of traumatic brain injuries.

"What we show in our work is that, in this population, assault is by far the most common mechanism of injury," Stubbs said.

"Women especially experienced traumatic brain injury oftentimes through intimate partner violence."

More research is needed into the topic, Stubbs emphasized, but he said he hopes the findings will be the first step to change.

"We need to better understand how the health of these individuals is affected by brain injuries," he said.

"Then we can better understand what can be done and that, hopefully, will lead into policy and practice."