The connection between homelessness and dementia
Authors: William J Panenka, Allen E Thornton, Jacob L Stubbs
Journal: The Lancet Public Health (2024)

Homelessness, a worldwide concern, reflects societal inequalities. Social, structural, cultural, and economic disadvantages contribute to poorer health and earlier mortality in homeless populations.1Fazel S Geddes JR Kushel M The health of homeless people in high-income countries: descriptive epidemiology, health consequences, and clinical and policy recommendations.Lancet. 2014; 384: 1529-1540Summary Full Text Full Text PDF PubMed Scopus (948) Google Scholar A high prevalence of brain health risks among individuals experiencing homelessness is also apparent, which is likely to contribute to observed progressive and non-progressive cognitive impairments and dementias. Compared with the general population, brain atrophy, white matter disease, and strokes have been found to appear decades earlier in people experiencing homelessness, as do many clinical geriatric syndromes.2Suh K Beck J Katzman W Allen DD Homelessness and rates of physical dysfunctions characteristic of premature geriatric syndromes: systematic review and meta-analysis.Physiother Theory Pract. 2022; 38: 858-867Crossref PubMed Scopus (2) Google Scholar, 3Zhou LW Panenka WJ Jones AA et al.Prevalence and risk factors of brain infarcts and associations with cognitive performance in tenants of marginal housing.J Am Heart Assoc. 2019; 8e011412 Crossref Scopus (9) Google Scholar, 4Stubbs JL Jones AA Wolfman D et al.Differential age-associated brain atrophy and white matter changes among homeless and precariously housed individuals compared with the general population.BMJ Neurol Open. 2023; 5e000349 Crossref PubMed Scopus (1) Google Scholar Despite a greater risk for poor brain health, the prevalence of dementia in people experiencing homelessness is unclear. In The Lancet Public Health, Richard Booth and colleagues5Booth RG Dasgupta M Forchuk C Shariff SZ Prevalence of dementia among people experiencing homelessness in Ontario, Canada: a population-based comparative analysis.Lancet Public Health. 2024; 9: e240-e249Summary Full Text Full Text PDF Google Scholar use public health data from Ontario, Canada, where a universal access single-payer system is in place, to evaluate the prevalence of dementia among homeless and housed comparison samples across age ranges. This represents one of the first population-level comparative studies in the literature. Previous studies, the majority of which also indicate elevated dementia prevalence in homeless populations,6Babulal GM Rani R Adkins-Jackson P Pearson AC Williams MM Associations between homelessness and Alzheimer's Disease and related dementia: a systematic review.J Appl Gerontol. 2022; 41: 2404-2413Crossref PubMed Scopus (0) Google Scholar are predominantly centred on US veterans, who might have a unique risk profile and access to services. After adjusting for demographic and clinical factors associated with dementia, Booth and colleagues report that the prevalence of dementia among those experiencing homelessness is significantly increased compared with a general population comparator group (prevalence ratio 1·71, 95% CI 1·60–1·82) and a low-income comparator group (1·90, 1·79–2·03). The results corroborate previous reports by adding evidence from a population-based Canadian sample, the message being that dementia in homeless populations is both under-recognised and prevalent. Although the high prevalence of dementia provides valuable observations, heightening concern for the poorer brain health of people experiencing homelessness, the findings of Booth and colleagues are likely to underestimate the burden of dementia. The reference standard used by the authors for dementia diagnoses was validated primarily to index age-related, progressive forms of dementia that are diagnosed in clinical settings rather than broadly capturing all forms of neurocognitive and functional decline represented across the many and diverse homeless communities. The approach potentially misses people experiencing homelessness who have suffered neurocognitive loss accompanied by functional decline due to traumatic brain injury, serious mental illness, and substance use disorders or associated syndromes. Moreover, the early mortality of people experiencing homelessness introduces survivorship bias, in which the dementia prevalence is attenuated by early mortality. Appreciating the diverse aetiologies of cognitive and functional decline is crucial to interventions targeting specific risk factors relevant to the population. The 2020 Lancet Commission report on dementia prevention, intervention, and care7Livingston G Huntley J Sommerlad A et al.Dementia prevention, intervention, and care: 2020 report of the Lancet Commission.Lancet. 2020; 396: 413-446Summary Full Text Full Text PDF PubMed Scopus (4054) Google Scholar identified 12 modifiable risk factors for dementia. Many of these risks are disproportionally represented among homeless individuals, including lower education, traumatic brain injury, substance use, smoking, mood disorders, and social isolation.1Fazel S Geddes JR Kushel M The health of homeless people in high-income countries: descriptive epidemiology, health consequences, and clinical and policy recommendations.Lancet. 2014; 384: 1529-1540Summary Full Text Full Text PDF PubMed Scopus (948) Google Scholar, 8Yuan Y Knight KR Weeks J King S Olsen P Kushel M Loneliness among homeless-experienced older adults with cognitive or functional impairments: qualitative findings from the HOPE HOME study.BMC Public Health. 2024; 24: 569Crossref PubMed Scopus (0) Google Scholar, 9Stubbs JL Thornton AE Sevick JM et al.Traumatic brain injury in homeless and marginally housed individuals: a systematic review and meta-analysis.Lancet Public Health. 2020; 5: e19-e32Summary Full Text Full Text PDF PubMed Scopus (79) Google Scholar Recognising key risk factors can guide prevention and appropriate triaging services. Other strategies could focus on those with existing dementia, such as establishing basic home care for those with irreversible cognitive and functional decline. A detailed understanding of the prevalence of dementia, trajectory of decline, and risk or protective factors is needed to allow us to understand the breadth and depth of the challenges. Improved understanding of brain health impairment in homeless populations will also help to lessen stigma. Neurodegeneration, brain injury, and cognitive impairment can contribute to difficulties with temperament and behaviour and are often stigmatised or attributed to so-called personality deficits or substance use. These challenges can serve as barriers to those who need support and highlight the necessity of appropriate trauma-informed care. Ultimately, dementia could contribute to the cycle of homelessness, whereby housing instability increases the risk for brain impairment, and brain impairment makes breaking the cycle of homelessness progressively more challenging. Booth and colleagues add to emerging work on the intersection of homelessness and neurodegenerative conditions and highlight a crucial public health concern at their intersection. The average age of homeless people is increasing and is now approximately 50 years in the USA,10Piña-Escudero SD López L Sriram S Longoria Ibarrola EM Miller B Lanata S Neurodegenerative disease and the experience of homelessness.Front Neurol. 2021; 11562218 Crossref PubMed Scopus (5) Google Scholar underscoring the immediacy and gravity of the public health problem. A multifaceted approach that integrates healthcare, housing, and social services is needed to better understand and alleviate the health consequences of homelessness. A concerted effort at all levels is vital to inform future public health efforts and stem the tide of increasing morbidity, compromised function, and early mortality in homelessness. WJP, AET, and JLL declare a research grant from the Canadian Institutes of Health Research. Prevalence of dementia among people experiencing homelessness in Ontario, Canada: a population-based comparative analysisPeople experiencing homelessness experience a high burden of dementia compared with housed populations in Ontario. Findings suggest that people experiencing homelessness might experience dementia at younger ages and could benefit from the development of proactive screening and housing interventions. Full-Text PDF Open Access