Submitted by acs95 on Tue, 06/01/2026 - 14:53
Name: Seb Walsh
Research group: PHAB – Public and mental Health, Ageing, and Brain
Supervisor: Carol Brayne
Second supervisors: Louise Lafortune (was Cambridge, now McMaster); Oli Mytton (was Cambridge, now UCL)
Advisor: Wendy Wills (Herts; NIHR ARC EoE)
Title of your PhD/MPhil: A population-level approach to dementia risk reduction
Can you give us a short background into what your PhD/MPhil was about?
Evidence has accumulated over recent decades that dementia risk can be lowered. The primary focus of the emerging dementia risk reduction field has been on lifestyle- or medical-based strategies based on targeting high-risk individuals. This PhD defines, develops the evidence base for, and makes the case for, adopting a population-level approach to dementia risk reduction. A focus on reducing risk for everyone across the population (not just high-risk groups) by changing the social, structural, and environmental factors that affect brain health over the lifecourse.
How would you sum up your main findings?
- Through review of public health and dementia risk reduction literature I defined a population-level approach to dementia risk reduction as ‘measures applied to groups of people with the aim of changing the social/structural/environmental conditions to make them less conducive to the development or maintenance of dementia risk factors (or more conducive to protective factors).’
- In a population-based cohort, I found that only around 10-30% of future cases of dementia occurred in people who were classified as ‘high-risk’ earlier in life, using the best available dementia risk scores. This means that we need a broader focus on the whole population if we wish to make significant reductions in future dementia prevalence.
- Through evidence and policy review work I identified a significant bias within dementia risk reduction research towards individual-level prevention interventions at the expense of population-level research; and a more balance policy landscape in England between dementia risk reduction policies across breadth and agency. This mismatch creates the risk of non-evidence-informed policymaking.
- Through qualitative work with English policymakers, I identified key barriers to greater policy adoption of population-level interventions for dementia risk reduction, including a lack of evidence, complexity of population-level policy design and implementation, and concerns about timeliness and measurability of outcomes.
- In a complex evidence review, I derived a framework of 26 policy recommendations for evidence-based population-level interventions for dementia risk reduction.
What made you want to do a PhD?
Normally my time is split between service/clinical public health work and research. So, the opportunity to spend 3 years focusing solely on research was a real blessing. Dementia risk reduction is an emerging field, and there was (and still is) a significant opportunity to advance population-level thinking within the field.
What was your best day during your PhD?
My second son, Oscar, was born 3 weeks into the PhD. It would have to be that!
What was your worst day during your PhD?
- The months and years of sleep deprivation following my best day during the PhD!!
- There were also challenges at times with lengthy evidence reviewing processes which meant weeks or even months of quite isolated working during which interactions with family and friends, and extracurricular work/hobbies were really important to keep me going.
- And of course, paper and grant rejections are a feature of academic life which can be very demoralising. My approach is to retain focus on the overall goal (making sure as many people as possible in tomorrow’s generation of older people do not get dementia) and that helps me build back my motivation and confidence.
Do you have any words of advice to future PhD/MPhil students in Psychiatry?
Fellowships go fast and slow at the same time. (Much like raising young children) the days can be slow but the years go fast. Find the balance between strategic planning and getting on with the job in hand. And try to find enjoyment every day – whether that’s from the work, giving presentations, learning new things from others, or just engaging with those around you.
What do you hope to do next?
I am currently completing my specialty training in public health. I am interviewing for postdoctoral clinical academic fellowships to continue studying dementia and healthy ageing in the population, with a focus on compressing morbidity.
I made a public-facing one pager summary of my PhD findings which is published on the Cambridge Public Health webpage: https://www.cph.cam.ac.uk/sites/default/files/dementia_prevention_summary.pdf