People experiencing homelessness more likely to develop dementia at younger ages, study finds

Dementia in unhoused people was 1.9 times greater than the general population, with a higher prevalence for age groups younger than 85 years, according to new research from Lawson Health Research Institute and ICES.

In one of the first population-based studies of its kind and published in The Lancet Public Health, researchers compared dementia prevalence in people experiencing homeless with the general population and people living in low-income neighborhoods in Ontario, Canada.

"Not only did we find that dementia was more common among unhoused individuals, but the difference was greatest between the ages of 55 to 64 years," says lead author Dr. Richard Booth, scientist at ICES and Lawson Health Research Institute, and associate professor and Arthur Labatt Family Research Chair in Nursing at Western University.

"There's a strong link between homelessness and accelerated aging, which may be one of the reasons people experience an earlier onset of the disease," says Dr. Booth.

Using a prevalence ratio, the researchers found that within the ages of 55–74 years, rates of dementia were 4 to 5 times higher than the general population and 3 to 3.5 times higher than the low-income group. There was a higher dementia prevalence in all age groups younger than 85 years among people experiencing homelessness in both males and females.

Unhoused people were younger on average, less likely to be female, and less likely to live in rural areas compared to the other two groups. They also had higher rates of health conditions associated with dementia, such as head trauma, neurological conditions, HIV, and mental health and substance use disorders.

After adjusting for factors such as age, sex, residential area, and health conditions, the prevalence ratio for people experiencing homelessness was 1.7 times higher compared to the low-income group, and 1.9 times higher compared to the general population.

"Other research has outlined that the rates of homelessness in older adults are expected to double by 2030, which means that the number of people living with dementia could rise substantially," says Dr. Booth. "Our findings suggest that unhoused individuals should be screened for dementia at younger ages, rather than waiting until age 65 as many guidelines suggest."

The researchers also note the complexity of diagnosing dementia in an individual experiencing multiple, chronic health conditions, as cognitive symptoms can overlap. Because of the difficulty in obtaining a medical history and diagnosis in this population, the study could have underestimated the true prevalence of dementia.

"We hope this work serves to enhance the awareness of policy makers and practitioners of the increasing prevalence of dementia among people experiencing homelessness," says study author Salimah Shariff, staff scientist with the Populations & Public Health Research Program at ICES, associate director of research operations and strategic partnerships at ICES Western, and associate scientist at Lawson.

"As housing is a core determinant of health and essential to the sustainment of individuals' health and well-being, access to permanent, supportive housing structures for people experiencing homelessness is also critical in preventing and slowing the progression of dementia in this population."