A Population-Level Approach to Dementia Risk Reduction

Dementia is a major public health challenge in the UK and globally. It is a significant cause of human suffering, and of health and social care burden, and the number of people living with dementia is projected to rise as the population ages. Despite advances in our understanding of the disease, treatment options remain limited. Evidence from the past decade or so has indicated that dementia risk can be lowered at the population level, and several modifiable risk factors have been identified. This thesis is inspired by a single question: how can we prevent as much of the future dementia burden as possible? To date, dementia risk reduction research has been heavily focused on ‘individual-level approaches’ – aiming to identify those individuals at higher risk of disease and work with them to lower their risk – and/or ‘high-agency approaches’ – aiming to lower risk through awareness campaigns and similar programmes that place the onus for behaviour change on the individual. Whilst important, such approaches are insufficient and inequitable because they do not address the underlying social conditions and environments that lead to the clustering and patterning of risk along socioeconomic gradients, and across generations. Instead, this thesis argues for a greater emphasis on lowering dementia risk at the population level by addressing these conditions and environments. The aim of this thesis is to work through the logical steps to equip policymakers, and those who work with them (e.g. public health professionals), with the evidence required to develop evidence-based, population-level dementia risk reduction strategies at both national and local levels. The first step (Chapter 1) is defining exactly what a population-level approach to dementia risk reduction is. This is achieved through the integration of what is understood about dementia epidemiology with established public health theories of prevention. The resultant definition is as follows: ‘Measures applied to populations, groups, areas, jurisdictions, or institutions with the aim of changing the social, cultural, physical, economic, commercial, environmental, occupational, or legislative conditions to make them less conducive to the development or maintenance of the modifiable lifecourse risk factors for dementia, and/or more conducive to the development or maintenance of the modifiable lifecourse protective factors for dementia.’ The next step (Chapter 2) is empirically demonstrating the need for a population-level approach in the context of dementia. This is achieved by showing, for the first time, that Rose’s hypothesis – ‘A large number of people at a small risk may give rise to more cases of disease than the small number who are at a high risk’ – holds for dementia. In a cohort analysis applying the best available dementia risk prediction scores within the population-based EPIC-Norfolk study, 70 to 90% of new dementia cases were found to occur in people classified as being at ‘normal risk’ at baseline, over three decades of follow-up. Accepting the need for a population-level approach, the next step (Chapter 3) considers the extent to which these principles are already embedded in current dementia risk reduction research and policy. A rapid review of reviews finds that dementia risk reduction research has been almost entirely focused on individual-level, high-agency approaches, with almost no contributing evidence that meets the thesis definition of a population-level approach. A scoping review of English prevention policy finds a more balanced picture, though clear opportunities for population-level policy development are identified. Increasing the emphasis placed on population-level strategies requires action from policymakers. Therefore, it is crucial to understand their perspectives on dementia risk reduction evidence and how this informs policy. The next step (Chapter 4) presents a thematic analysis of semi-structured interviews with English policymakers, elucidating key barriers and facilitators to greater adoption of population-level approaches to dementia risk reduction. The final step (Chapter 5) is to develop a policy framework for what a population-level approach to dementia risk reduction should look like in practice. A complex evidence review methodology is used to identify 26 policy recommendations for population-level interventions that are evidenced to reduce the risk factors for dementia. How can we prevent as much of the future dementia burden as possible? Through the examination of public health theory, generation of new quantitative and qualitative evidence, and reviews of policy and existing evidence, this thesis aims to help answer that question by defining and building the evidence base for a population-level approach to dementia risk reduction.

Name dc:type.qualificationname

Doctor of Philosophy (PhD)

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

University of Cambridge

Year dc:date.issued

2025

Author dc:creator

• Walsh, Seb

Advisors dc:contributor.advisor

• Brayne, Carol
• Lafortune, Louise
• Mytton, Oliver
• Ford, Tamsin

• Dementia
• Population-Level
• Risk Reduction
• Prevention
• Public Health

Licence

• https://www.repository.cam.ac.uk/bitstreams/2af900ae-2f2d-4629-9a86-92e8ef579fbf/download
• https://creativecommons.org/licenses/by/4.0/

Language dc:language

eng

Author Identifier

0000-0001-8894-5006

OAI identifier oai:identifier

oai:www.repository.cam.ac.uk:1810/393502