‘Improving the safety, quality, and stability of people’s environments should encourage healthy behaviour’

Why are those who are more likely to die due to factors beyond their control less motivated to take care of their own health? That's the question at the heart of the Uncontrollable Mortality Risk hypothesis, and of my own PhD project. 

I've been inspired by the work of Dr Gillian Pepper, a psychology lecturer at Northumbria University and my supervisor. Her research focuses on socioeconomic disparities in health, investigating how structural inequalities affect human behaviours, and go on to impact health and longevity. Gillian uses evolutionary theory and observational and experimental data to examine differences in psychology, health and social behaviour. 

We sat down to discuss the origins of Gillian's approach, and how she feels this line of research could help to tackle class-based inequalities in health. 

How did you become interested in studying health inequalities?

I've been interested in biology and in health since I was an undergraduate student. My first ever academic paper, which came out of my undergraduate thesis, was about the possible protective function of morning sickness. After graduating, I spent some time working for the Department of Health, where I learned of some of the practical challenges of health improvement. 

During that time, I read The Spirit Level, by Richard Wilkinson and Kate Pickett, and also Status Syndrome by Michael Marmot. Both books make convincing cases for tackling inequalities in power and wealth in order to improve public health. They raised my awareness of the importance of tackling inequalities, not just for the health of those who are victims of inequality, but also for the wellbeing and prosperity of societies more generally. 

I started working on this topic in my own very small way by investigating the psychological impact of perceived inequality as part of my MSc thesis, and my interest grew from there. Then, I was lucky enough to get a PhD scholarship with Daniel Nettle at Newcastle University. He does some excellent work on health inequalities and is using novel theoretical and methodological approaches to try to untangle the causes and effects of inequality. During those PhD years, my work focused on the effects of perceived risk on behaviour, which is relevant because there are social class inequalities in exposure to numerous health risks. Examples include violent crime, pollution, poor housing (think damp, mould, and flammable cladding), and even Covid-19. Since then, I've also worked on understanding the biological mechanisms underpinning inequalities in health and ageing, as well as some of the other aspects of health inequalities, such as food insecurity.     

What are some of the class-based health inequalities in the UK today? What do you think are the causes?

People living in more affluent areas of the UK can expect to live significantly longer than those living in the least affluent areas. They can also expect to live for much longer in a good state of health. The Office for National Statistics has found that, in recent years (2017-2019), an average man in one of the most deprived parts of the country could expect to live 9.4 years fewer than an average man in one of the most affluent parts of the country. For women, the gap is 7.6 years. The inequality is even bigger when we consider how long people can expect to live in good health: the healthy life expectancy gap for men is more like 18 years, with the gap for women being close to 20. 

These health inequalities are a result of broader inequalities in wealth, power, education and living standards. Just think about the extent to which having money buys people control over their health. If you have more money, you can afford to live in a better, safer neighbourhood. You can afford to eat better quality food, and to pay for all sorts of comforts and conveniences to keep yourself well and reduce the stresses of life.  

Education can have a similar effect as it opens up job prospects and also because, as the saying goes, knowledge is power. If you have more education, that might allow you to secure a job with better working conditions and better pay (which, of course, would mean that you have more money). It may also mean you can navigate complex health and social care systems with greater ease. Though it's not necessarily a direct effect of wealth or education, people from wealthier and more educated backgrounds also tend to be connected to more powerful people, who may be able to help them in various ways. If you aren't lucky enough to grow up as part of a well-off family, it is harder to achieve a good education and to become an affluent adult. You will likely have to accept living in poorer quality housing in a less safe neighbourhood. You may also end up working in a less secure job or one where you're exposed to more hazards. 

In short, higher social class affords you a safer and more predictable living environment, with a greater degree of control over your life. This has been the focus of a lot of my work because, as psychologists, we're interested in behaviour, and people's behaviours are strongly affected by their environments. 

So what behaviours do we see emerging from those environments?

Unhealthy behaviours are thought to account for a reasonable portion of the social class gradient in health – up to half, depending on which estimates you look at. Certainly, lifestyle diseases such as heart disease, diabetes and certain forms of cancer are responsible for a high proportion of deaths each year – around 70 per cent globally according to the World Health Organisation. So, it's important to understand what drives the behaviours linked with those diseases. According to the Uncontrollable Mortality Risk hypothesis, an accumulation of unavoidable risks in our environments should be one of those drivers.

This perspective gives us a helpful reminder that behaviour doesn't occur in isolation. Informational health campaigns that target key health behaviours, such as diet, exercise, smoking and alcohol use, will only have limited effects if structural inequalities aren't also addressed. However, by identifying which elements of people's environments have the biggest impacts on their behaviour, it might be possible to reap double benefits. First the initial benefit of the environmental improvement itself, but also the benefits of resulting improvements in health behaviour. In short, understanding how people's environments influence their health behaviours can help us to identify where best to focus limited public health resources to produce the maximum impact.

What's your approach to explaining health behaviours?

A key focus has been to explore the role that perceptions of control over risk might play in determining health behaviours. The idea is that it may be reasonable to expect that those from deprived backgrounds should be less motivated to take care of their health compared with those who are better off, because of the environmental conditions they experience. The reason for this is that looking after your health takes effort. We believe that there is a trade-off between investing in your long-term health, and doing other things. The more time and money you devote to the gym and following a healthy diet, for example, the less you have for other activities, like socialising, finding a partner, or working your way up the career ladder. 

The approach stems from behavioural ecology. Previous work in evolutionary biology has often discussed the influence of environmental conditions on how an organism might allocate energy throughout its life. This typically suggests a trade-off between growth and reproduction, with the ideal timing, and amount of energy spent on each, depending on the conditions of the environment. However, instead of explaining the investment of energy in terms of the physiological interests of growth and reproduction, our work suggests a trade-off between the behavioural investment in health versus any other activity that could improve an individual's 'fitness'. Here we mean 'fitness' in the Darwinian sense, reflecting how well adapted an organism is to its environment for the purpose of contributing the most offspring to the next generation. Activities that might compete with investing in your long-term health might include increasing one's social status or dominance, accumulating necessary resources, or looking for a partner, all of which might help someone to optimally adapt to their environment.

So can you say more about how that might feed into class-based differences? 

All of this comes from a theoretical model by Daniel Nettle, in which he took some of these evolutionary life history principles and thought about how they could be applied to explaining social class differences in health behaviour. 

The negative effects of lower social class may reduce the potential payoff of investing in healthy behaviours. This means that, assuming the trade-off between investing in long-term health and other activities, the ideal amount of health effort may be reduced for those in lower social-class positions, which causes the secondary effect of reduced motivation to follow a healthy lifestyle. We argue that humans may have evolved to be sensitive to environmental cues of risk, such as the levels of violence or potential danger that people experience in their surroundings. We suggest that we might expect psychological mechanisms to respond to these cues of risk by determining the level of investment in preventative health behaviours. This helps us to offer an explanation for the differences we see in the extent to which people prioritise their long-term health.

To sum this up, the Uncontrollable Mortality Risk Hypothesis states that those who are more likely to die due to factors beyond their control should be less motivated to take care of their health because they are less likely to live to see the long-term benefits of a healthy lifestyle, and their efforts could be put into other more immediately rewarding activities. Class-based inequalities in health are therefore in some part related to the fact that less affluent people tend to experience more uncontrollable risks than more affluent people. For example, people from poorer backgrounds experience greater risk of violent crime in their local area, are exposed to greater levels of air pollution, and even higher Covid-19 infection and fatality rates. Believing you are likely to die due to factors that are beyond your control may make you less motivated to invest time and energy in your long-term health. As you once put it, Richard, 'If you believed there was nothing you could do to avoid being the victim of a stabbing in the next few years, would eating your five a day seem that important?' 

Have you tested the Uncontrollable Mortality Risk hypothesis?

Yes, a lot of the work that Daniel Nettle and I have done together has been about testing the Uncontrollable Mortality Risk Hypothesis. Initially we developed a measure of perceived uncontrollable mortality risk. The idea was to capture the extent to which people think they can avert a premature death by changing their behaviour. It makes sense that believing your actions won't make much of a dent in your overall health and mortality risk might lead you to deprioritise healthy living. We found evidence consistent with this prediction. In our first survey, we found that less wealthy people felt that their risk of premature death was much less within their personal control. Those same people also reported making less effort to look after their health. A good part of this association between affluence and healthy behaviour was, statistically speaking, explained by this measure of perceived uncontrollable mortality risk which we'd developed. 

We followed this up with a series of experiments to see if making people think that their personal risk was more controllable would affect health behaviour. We used fake life expectancy calculators to alter perceptions of control over longevity and then offered people a simple choice: a box of organic fruits, or a box of chocolates of equal monetary value. When people had been primed to believe that they faced uncontrollable risks that would affect their longevity, they were more likely to take the chocolate. When they were primed to believe that individual health behaviours were the main risk to their longevity, they were more likely to choose fruit. (Don't worry, we did tell them that it was a fake life expectancy calculator once the experiment was over!)

Of course, countless environmental and individual factors may combine to influence food choices. However, the results of these experimental studies suggest that perceptions of uncontrollable mortality risk have a considerable effect on the likelihood of choosing a healthy food option, when presented with an unhealthy alternative.

As you know, I've looked to add to this picture with work during the early stages of the Covid-19 pandemic. That showed associations between perceived uncontrollable mortality risk, which had increased due to the pandemic, and self-reported diet, exercise and smoking behaviours. I'm now looking at what sorts of risk are perceived to be least controllable by people here in the UK, and how those perceived risks differ by social class. 

I'm really looking forward to seeing what you find… these are really important and interesting questions. A key implication of our research findings, and those of many other researchers, is that improvements in the safety, quality, and stability of people's living and working environments should encourage spontaneous improvements in health behaviour. So, if we focus on improving people's living conditions, they should reap that double dividend. This implies that we shouldn't need to spend money on behaviour change campaigns if we were to focus on reducing inequalities in wealth and power. The challenge is that health communications and behaviour change campaigns are often presumed to be cheaper and easier to implement than the measures required to tackle structural inequalities. I would argue, however, that this is a false economy when those campaigns aren't effective. Indeed, some well-intentioned public health campaigns targeted at changing individual behaviours have been shown to widen inequalities.

Despite that, our work has yielded some insights that perhaps could be used to guide public health messaging. For example, your findings during the early stages of the Covid-19 pandemic suggested that increasing people's sense that the virus was a threat would improve compliance with Government advice around controlling the virus, but it could also have had the unintended consequences of increasing perceived uncontrollable mortality risk and thereby reducing people's motivation to eat well, exercise, and not smoke.   

Further insights come when you think about people's time horizons. When communicating with people who face a larger burden of uncontrollable risk, they might not believe that they'll live long enough to see the deferred benefits of healthy behaviour. In this case, focusing on the shorter-term benefits of healthy behaviour (e.g., more attractive skin) rather than the longer-term ones (reduced risk of cancer in later life) might be more effective. Nonetheless, such communications-based approaches should still be secondary to actually reducing disparities in exposure to risk.  

Given the current cost of living crisis, many households are struggling to put food on the table. What have you learned from your recent research into food insecurity?

There are many reasons why food insecurity is bad for health. Most obviously, it can mean inadequate nutrition. Even where people don't face a calorie deficit, they may find themselves eating cheap, ultra-processed foods, which tend to contain an excess of fats, salt and sugars and often lack important micronutrients. This is likely to be one of the reasons why the less extreme type of food insecurity, that occurs in high income contexts, seems to be associated with obesity. However, evolutionary theory also suggests that the experience of unpredictability in food supply may drive weight gain as an adaptive response to food insecurity. This is known as the Insurance Hypothesis and my colleagues Daniel Nettle, Clare Andrews, Jackie Shinwell and Melissa Bateson have done some interesting work to investigate the idea.

Food insecurity can also be thought of as a stressor. Think about how essential food is for our survival and how stressful it must be to not know where your next meal is coming from, or to struggle to figure out if you can afford to eat lunch today. The effects on wellbeing alone should be a concern, before we even think about the longer-term health consequences. My colleagues at the Healthy Living Lab at Northumbria University are doing some very important work on food insecurity, which they started long before I joined the team. However, I recently joined Greta Defeyter, Paul Stretesky and Emily Mann in a project on food insecurity, stress and wellbeing during the Covid-19 pandemic. We looked into the role of food insecurity in the association between economic hardship and stress and wellbeing during the pandemic. Watch out for more on our results! 

How do you hope your line of research might be implemented to help tackle class-based inequalities in health? 

As I've already mentioned, a key implication of some of our findings is that our health behaviour is affected by those things which are beyond our personal control. Obviously, a core role for governments is to manage collective goods. This means that governments do have the ability to tackle those things which are beyond the reach of the individual. It feels like it should be obvious that managing such things should be the role of governments. However, there are also a lot of government-led projects, particularly in public health, that aim to intervene at the individual level. Perhaps this is because 'nudging' and behaviour change campaigns which can be targeted at individuals have a certain allure. They're perceived as cheaper, easier and 'lighter touch'. But I think some work needs to be done to identify those things that people find hardest to tackle for themselves, so that we have an idea of the areas in which governments could have the most impact. Ideal targets would be things that people think are highly uncontrollable for them personally, which are known to have a meaningful impact on health and longevity. Some of these things may be challenging to tackle, but we've got to at least aim for that double dividend – the value of the intervention itself, and the secondary effect of the improved health behaviour we would expect in response.