One in two homeless people may have experienced a head injury in their lifetime

The meta-analysis -- which looked at 38 studies published between 1995 and 2018 -- is the first to look at the prevalence of TBI in people who are homeless or in unstable housing situations.

The results suggest that one in two (53 per cent) homeless people experience a TBI, and one in four (25 per cent) experience a TBI that is moderate or severe.

After comparing their estimates to studies of the general population, the researchers estimate that the lifetime prevalence of TBI in people who are homeless and in unstable housing situations could potentially be up to four times higher than in the general population. Meanwhile, the lifetime prevalence of moderate or severe TBI in this population could be nearly 10 times higher than estimates in the general population.

Based on the data they analysed, the researchers were unable to determine whether TBI increased the risk of homelessness or whether homelessness increased the risk of TBI. While more research is needed to better understand the relationship, the researchers say the findings suggest that providing stable housing might lower the risk for TBI.

"More research is definitely needed. TBI is an underappreciated and significant factor in the health and functioning of this vulnerable group of people," says the study's senior author Dr. William Panenka, assistant professor in the UBC faculty of medicine, a member of the BC Provincial Neuropsychiatry Program at UBC and a part of the BC Mental Health and Substance Use Services Research Institute.

"I find it especially striking that we found such a high prevalence of moderate or severe TBI," says Jacob Stubbs, the study's lead author and a PhD student in Panenka's laboratory. "Our work emphasizes that healthcare workers be aware of the burden of TBI in this population, and how it relates to health and functioning."

TBI can range from a mild concussion to a severe head injury. It is caused by a blow to the head or body, a wound that breaks through the skull, a fall, or another injury that jars or shakes the brain causing bruising, swelling, or tearing of brain tissue.

With time, most people recover from a mild brain injury but some people, especially those have repeated or severe injuries, may have long-lasting problems with movement, learning, or speaking.

For their study, the researchers looked at 38 published papers from six high-income countries -- Australia, Canada, Japan, South Korea, the UK, and the USA -- which included people of any age who were either homeless, in unstable housing situations, or seeking services for homeless people.

They examined the number of new cases and existing cases of TBI, and the association between TBI and health or functioning outcomes.

Their findings suggest that TBI is consistently associated with poorer self-reported physical and mental health, suicidality and suicide risk, memory concerns, increased health service use and criminal justice system involvement.

The authors suggest a need for health-care workers to have increased awareness of the burden and associated effects of TBI in people who are homeless, noting that more comprehensive assessments of their health -- including checking for a history of TBI -- may help improve their care.