<p>A man using a rolling walker walks on the street past tents setup on the sidewalk at a sprawling homeless encampment on East Hastings Street in the Downtown Eastside of Vancouver, on Tuesday, August 16, 2022. &nbsp;THE CANADIAN PRESS/Darryl Dyck</p>

People who are homeless have a higher risk of developing dementia at a younger age compared to the general population and those from the lowest income neighbourhoods in Ontario, suggests a study that calls for housing and earlier screening for this group.

The study used health-care administrative data for every patient aged 45 and older who visited an emergency room, community health centre or was hospitalized in 2019.

It looked at the age, sex, residential area and health conditions of12,863 people who were experiencing homelessness, 475,544 in the low-income group and more than 2.2 million from the general population.

The study, published Wednesday in The Lancet Public Health, found that dementia in people who were homeless was 1.9 times higher than the general population and 1.7 times higher compared to people with a low income.

Lead author Richard Booth, a scientist at the research institute ICES, said those numbers are likely an underestimate of dementia because patients may not have disclosed they were homeless, especially if they were couch-surfing or living in their car.

"Even if we under-represent the number of people being homeless, we still see that the prevalence of dementia is way higher than the comparator cohorts in Ontario," said Booth, also a scientist at the Lawson Health Research Institute in London, Ont.

He said that as a first step, policy changes should provide supportive housing for those who need it as well as screening for dementia when people show signs of memory loss or other cognitive deficits.

"You cannot have wellness and health unless you have housing," said Booth.

Dementia was listed in health records more frequently for those aged 55 to 64, pointing to the need for screening based not on guidelines that may recommend it at age 65 but on people's social and clinical situation, the study notes.

It's possible that people who had dementia ended up becoming homeless, Booth said, but that question can't be answered by the study, funded by the Public Health Agency of Canada.

As with other studies, the researchers found that people who were homeless had higher rates of neurological conditions, mental health, HIV and substance use disorders, all factors that contribute to dementia.

Brain injury, often due to violence and falls following use of alcohol and illicit substances, is also common among that population.

The study found that 22 per cent of people who were homeless had a head injury, more than triple the rate of the general population.

Lack of housing and unaffordability in general means "the homelessness situation be will far, far worse. And the outcome of people with dementia who are homeless is very poor," Booth said.

"You don't know where your next meal is coming from and you have dementia. You can already guess what the outcome on that trajectory is. It's a terrifying thing to think about these numbers."

Dr. Martha Spencer, a geriatrician at St. Paul's Hospital near Vancouver's impoverished Downtown Eastside, said she sees unhoused people in their 50s and 60s starting to develop cognitive conditions that are more common among those in their 70s and 80s.

That's in keeping with a study from the United States published a year ago in the journal Frontiers in Public Health. Researchers reviewed 14 studies on older people experiencing homelessness and concluded that those betweenthe ages of 40 and 59 often have geriatric conditions that are typically found in those aged 70 to 89.

Spencer said standard screening tools for dementia include questions about short-term memory such as remembering a set of words, drawing a clock and copying a figure but they are typically used on people with higher levels of education.

"I worry that using those cognitive tests may be unfair" for those who are homeless, said Spencer, adding that functional assessments may be a more reliable measure of that population's day-to-day experience, including whether people remember to shower, for example.

Staff at shelters or outreach teams may notice signs of dementia over time and should refer people to a care provider, Spencer said.

Michelle McDonald, CEO of Brain Injury Canada, said staff at women's shelters should know that intimate-partner violence may cause head trauma that could lead to memory problems and possibly dementia in those who are not elderly.

"They may be injured through punches to the head. That education is going to be key to changing the way people are supported," McDonald said.

"In Canada, we track incidents, hospitalization and emergency department visits for brain injury. But we don't track what happens to people long term. It would be helpful to know how many people do have dementia with traumatic brain injury later in life."

This report by The Canadian Press was first published March 27, 2024.

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