Stress in childhood and over the life course – our bodies pay the price

When I was in my teens, there was a popular Monty Python sketch where four Yorkshiremen sat around reminiscing, trying to best each other with claims of how poor they were as children. In 1976, when the show was made, fewer than 15% of children in Great Britain were living in relative poverty.

More children living in poverty

It's deeply troubling to consider how things have changed since the 1970s. Close to 40% of children in the UK are predicted to be living in poverty by 2021, as reported by Philip Alston, Special Rapporteur on extreme poverty and human rights in his recent update to the UN General Assembly. And 4.5 million children were living in poverty in the UK in 2018, according to the Social Metrics Commission.

The number of children living in poverty in the UK is a cause for concern not just in itself, but also because of the consequences it will have for the health outcomes of these children and young people across their life course. Poor housing, limited access to educational and employment opportunities, and poor diet are all likely to have damaging effects on the health of children and young people living in poverty today.

But there is another cause for worry about the long-term consequences of poverty and other sources of stress which children and young people face. We physically adapt to our environments, and this process of adaptation is particularly marked while we are developing as we grow up. All environments affect us biologically, sometimes in a positive way, sometimes the effect is neutral, and sometimes the effect is negative. These exposures, or experiences, can come to be absorbed into our bodies' cells, organs and systems, ultimately affecting our health.

Adapting to challenges comes at a cost

A growing body of research is expanding our knowledge and understanding of the biological consequences of social and economic disadvantage experienced in childhood and youth. It also reveals how these contribute to health inequalities later in life. This research employs the concept of allostatic load: the price the body pays for adapting to the challenges it experiences – physical, social and psychological.

An allostatic load score is a measure which combines biological indicators (or biomarkers) of various physiological systems to capture sub-clinical overall physiological wear and tear. In other words, it brings together a range of indicators, which can be found before a condition is severe enough to present definite or visible symptoms, into a single score. There is some variation in the components of an allostatic load score, but the markers most commonly used are associated with cardiovascular and metabolic diseases, the stress response and sympathetic nervous systems, and inflammation.

Greater disadvantage can increase allostatic load

In Allostatic load, published this week, we review the growing evidence suggesting young people exposed to stressors in early life are at risk of developing serious non-communicable diseases and poor health later in life through allostatic load. The report finds that across a number of studies (including one systematic review), socioeconomic disadvantage has been associated with a higher allostatic load score and increased allostatic load has been linked with multiple chronic disease outcomes.

For example, work by Barboza Solis and colleagues in 2015 highlighted the role of childhood material disadvantage, educational attainment and body mass index as being important ways in which experience of disadvantage in early life affected later physiological wear and tear. The recent extension of the period of transition into adulthood is a potential cause for concern, as it may extend young people's exposure to stress.

Allostatic load has its critics. It is not necessarily measured consistently across studies, and in some cases the biomarkers used to calculate allostatic load do not reflect the theoretical basis of the concept. Currently, there is no consensus about which biomarkers should be included to calculate allostatic load. However, it is a fascinating area of research which is rapidly developing in response to the new opportunities offered through the availability of biomarker data in some of the UK's longitudinal cohort studies and in other countries' datasets. It has only been in the last decade that datasets containing quality social and biological variables have started to become available to researchers.

The way forward: stem poverty and foster lifelong wellbeing

What I find exciting about this area is that it raises the possibility that we can do something about future health inequalities by addressing factors which contribute to a high allostatic load. Tackling child poverty and providing better access to good quality housing and education could help to improve health now; and to reduce the stress that may lead to poor health in the future. Policy initiatives to relieve poverty and disadvantage among children and young people may not just help them in their current lives, but also provide an environment that is less chronically stressful. Furthermore, such initiatives could provide a buffer against other stressors which will contribute to better health over the lives of those most likely to be affected.

Allostatic load is key to the work of the Health Foundation's Young people's future health inquiry. The inquiry has been looking at the pathways of young people between the ages of 12 and 24, and the ability of young people to lay down the building blocks for a healthy life. This autumn we will be launching final recommendations for policymakers to address the key areas that impact on young people's future health. Watch this space.

Liz Cairncross is a former Research Manager at the Health Foundation.