28 March 2024

Homeless Canadians found to have an increased risk of developing dementia

A population-based study has found that homeless people face a greater burden of dementia compared to the rest of the population living in Ontario. As reported in The Lancet Public Health, homeless people are more likely to have dementia at a younger age.

Dementia is considered the seventh leading cause of death and disability. There are various modifiable risk factors that contribute to the development of dementia. These include, for example, brain injuries, obesity and low motor activity. While prevention targeting these factors is available for most people, it may be difficult for some due to unfavorable life situations.

These situations can include homelessness. Among the homeless, there are often high rates of morbidity and mortality associated with substance use, mental health disorders, social isolation, and brain injury - risk factors for dementia. Thus, it is hypothesized that homelessness may increase the risk of developing dementia, but the potentially bidirectional relationship that exists between homelessness and dementia is complex and multifactorial. For example, the onset of dementia may be exacerbated by a variety of adverse social and health conditions commonly experienced by homeless people. Conversely, cognitive decline at the onset of dementia, may predispose to homelessness.

A team of researchers led by Richard Booth of the University of Western Ontario conducted a population-based study to compare the risks of developing dementia in three cohorts of the Ontario population: homeless people (12863 people), low-income people (475544 people) and the general population (2273068 people). The homeless were younger and more likely to be male; they were more likely to have head injury, chronic obstructive pulmonary disease, epilepsy, HIV infection, and mental disorders. At the same time, they were less likely to have a diagnosis of hypertension.

The overall prevalence of dementia in 2019 was 68.7 per 1,000 population in the homeless population, 62.6 per 1,000 population in the low-income group, and 51.0 per 1,000 population. Tellingly, the prevalence of dementia increased with age in all groups and in both sexes. With the exception of those over 85 years of age, the prevalence of dementia was highest among the homeless, followed by low-income groups and the general population.

The relative risks of developing dementia in those younger than 85 were also statistically significantly higher among homeless people of both sexes compared to the low-income group or the general population. Among women, relative risk peaked at ages 55-64 years (4.78 compared with the general population) and 65-74 years (3.96). Similarly, among homeless men, the prevalence of dementia was markedly higher in the age groups 45-54 years, 55-64 years, and 65-74 years.

After adjusting for demographic characteristics and comorbidities associated with dementia, the prevalence rate of dementia among homeless people was 1.71 compared with the low-income group and 1.90 compared with the general population. In the multivariate analysis, the most significant factors associated with dementia prevalence were diagnosis of HIV infection, multiple sclerosis, and parkinsonism.

Researchers believe that screening for dementia among homeless people, especially at younger ages, will help reduce its prevalence in this cohort through the development of integrated care approaches and improved access to specialized housing.

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