Disturbing new statistic uncovers link between homelessness and brain health

"It often times gets lost in the myriad of other problems that these people face."

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For the homeless, a bump, knock or blow to the head might go unnoticed among other, more pressing issues, like where to sleep safely that night. But a startling new statistic suggests these frequent hits to the head should be anything but ignored. In fact, they could be the reason for the myriad other health issues the majority of homeless people have.

An estimated 53.4 percent of homeless or marginally-housed individuals have suffered some sort of traumatic brain injury at some point in their lives.

These injuries can underlie other conditions, including poor physical and emotional health, like suicidality, or memory problems, says Jacob Stubbs, a graduate student at the University of British Columbia.

“TBI is often not the most acute or pressing concern, but what we’re showing with this study is that TBI is often under-recognized and is actually linked to many different mental and physical health problems,” Stubbs tells Inverse.

The troubling statistic comes from a meta-review that analyzed 26 studies on homelessness and health. The review was published this week in the journal Lancet Public Health. The study suggests that to get a full picture on health among the homeless, scientists need to look beyond the commonly-held stereotype that substance abuse underlies many of the problems homeless people grapple with.

The reality of homelessness

On a single night, an estimated 553,000 Americans are homeless, according to the US Department of Housing and Urban Development. About two thirds find refuge in a shelter, but the rest either remain on the street or in places deemed “unsuitable for human habitation” after dark. In Canada, where this study was conducted, an estimated 35,000 people are homeless on any given night.

People wait for Thanksgiving meal at the Los Angeles Mission, in Los Angeles, California, USA, 27 November 2019.


William Panenka, the study’s senior author and associate professor University of British Columbia, points out that substance abuse among the homeless has dominated scientists’ attention. And not without cause: A 2013 study from Panenka’s group found that in a sample of 3,000 individuals housed in Vancouver’s single-room occupancy hotels, 95 percent had substance abuse issues.

"It often times gets lost in the myriad of other problems that these people face."

But those individuals also reported having an average of three co-occurring illnesses, suggesting that health problems among the homeless goes far beyond high rates of substance. Among those other diagnoses were unusually high rates of traumatic brain injury — a result that inspired the new study.

A traumatic brain injury is often caused by a blow to the head that disrupts brain function. Their consequences can range from mild concussions to severe, life-altering brain trauma.

The review suggests that traumatic brain injury is prevalent across homeless populations in the United States, Australia, the United Kingdom, South Korea, Canada and Japan. These injuries are often serious: 24.9 percent of homeless and housing insecure people suffered a severe traumatic brain injury — the kind that can seriously upend someone’s life. And because they are homeless, people often don’t get the care they need.

“There’s a lot going on, which makes it really daunting for someone to take this person and try to shunt them to appropriate care,” says Panenka. “It often times does get lost in the myriad of other problems that these people face.”

Brain injury takes center stage

The paper suggests that homeless or marginally housed people suffer from traumatic brain injuries far more than expected, — at least twice as often to ten times as often compared to the general population.

But the data weren’t enough to say whether these injuries are a cause or a consequence of homelessness. The team argues that it’s probably both.

Experiencing such an injury could exacerbate mental or physical health issues that can lead to homelessness and degrade quality of life. At the same time, not having a safe place to rest each night can raise the risk of experiencing this kind of trauma.

Disturbingly, assault was the most common cause of traumatic brain injury, according to this analysis.

"You can kind of forsee where this might go — which gives you a chance at earlier intervention.”

That finding only adds to an already bleak picture.

If traumatic brain injury is the result of an assault, the repercussions only intensify. “We suspect that the repercussions of having a brain injury are somewhat secondary to someone assaulting you,” Panenka says. It could affect how conditions like post-traumatic stress disorder develop, for example, he says.

“You can see where if you’re aware of the TBI, and you’re aware of the certain circumstances, if you put that together with the patient’s own mental physical health, you can kind of forsee where this might go — which gives you a chance at earlier intervention.”

In other words, these trauma may not be on the radar for many scientists or clinicians now, but in the future, they could be offer clues to the right kind of care for someone who needs it.

Partial Summary:
Methods: For this systematic review and meta-analysis, we searched without date restrictions for original research studies in English that reported data on the prevalence or incidence of TBI, or the association between TBI and one or more health-related or function-related outcome measures. Studies were included if they had a group or clearly identifiable subgroup of individuals who were homeless, marginally housed, or seeking services for homeless people. With use of random-effects models, we calculated pooled estimates of the lifetime prevalence of any severity of TBI and the lifetime prevalence of moderate or severe TBI. We used meta-regression to evaluate potential moderators of prevalence estimates and the leave-one-out method for sensitivity analyses. We then summarised findings from all studies that evaluated TBI incidence and the association between TBI and health-related or functioning-related outcomes. All statistical analyses were done using R version 3.5.1. The study is registered with PROSPERO, number CRD42019119678.
Findings: Of 463 potentially eligible studies identified by the search, 38 studies were included in the systematic review and 26 studies were included in the meta-analysis. The lifetime prevalence of any severity of TBI in homeless and marginally housed individuals (21 studies, n=11 417 individuals) was 53·4% (95% CI 47·6–59·1; I²=97%) and the lifetime prevalence of moderate or severe TBI (12 studies, n=6302) was 24·9% (16·3–35·9; I²=98%). The definition of TBI, the method used to ascertain TBI history, and the age of the sample significantly moderated estimated lifetime prevalence of any severity of TBI. TBI was consistently associated with poorer self-reported physical and mental health, higher suicidality and suicide risk, memory concerns, and increased health service use and criminal justice system involvement.

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