Social and economic adversity, especially in early life, may accelerate the biological aging process, but such an effect is reversible. The biological age of individuals living in poor socioeconomic circumstances is, on average, one year higher than that of people raised in better social environments. This is what emerges from the study conducted by an international team of researchers of Lifepath, a project funded by the European Commission to investigate the biological pathways underlying social differences in healthy ageing.

According to a study they published in Scientific Reports, the aging acceleration effect of low socioeconomic conditions was comparable to that estimated for obesity, unhealthy diet, and alcohol consumption. Of the known risk factors analysed, only smoking showed a higher effect on biological aging.

Poor socioeconomic circumstances are associated with lower life expectancy and earlier onset of age-related chronic conditions, but the biological mechanisms that mediate this association are still not fully understood. To shed light on these processes, Lifepath researchers performed a series of analyses on more than 5,000 individuals from Australia, Ireland and Italy, using some indicators known as epigenetic clocks to estimate whether an individual is experiencing accelerated or decelerated aging. In fact, the biological age of most tissues and cell types can be assessed by measuring the level of DNA methylation – which is the addition of a methyl group to the DNA molecule – in particular parts of the genome called CpG sites. Such a process occurs naturally and represents one of the main ways of regulating gene activity, but its speed and intensity may vary, depending on several internal and external factors.

“The estimation of ageing acceleration based on DNA methylation is, at the moment, the best biological age predictor”, says Giovanni Fiorito, Post Doc fellow at the Italian Institute for Genomic Medicine and leading author of the study. “It correlates well with the chronological age, is higher in individuals that have an unhealthy lifestyle, in those with chronic diseases, and predicts mortality”.

Lifepath researchers measured individuals’ epigenetic clocks and compared them with some indicators of their socioeconomic conditions, such as level of educational attainment, occupational position, household income, and a deprivation index. They found that the biological age of people from lower socioeconomic environments is, on average, one year higher than that of people of the same chronological age but who live in better social circumstances.

Yet, such an effect is not irredeemable.

Individuals whose childhood socioeconomic conditions were low and remained low in adulthood experienced an accelerated aging compared to those that managed to improve their social and economic circumstances during the course of life.

To this regard, the relationship between the social environment and biological aging seems to be particularly responsive to early life social influences. Probably because, as shown by recent studies, the effects of early life exposures to better social and economic conditions may be memorised by our cells through a series of epigenetic modifications, including DNA methylation, that can be sustained for decades.

“Our study adds another piece to the puzzle of understanding the biological mechanisms that may link social adversities to age-related diseases and longevity”, concludes Fiorito. “Further, we provide evidence that early life social environment leaves an epigenetic signature on our DNA that is at least partially reversible by improving social and lifestyle conditions”.

This is the largest study investigating the relationship between social adversity and epigenetic clock in peripheral blood in adults. Its results confirm previous observations that socioeconomic conditions are a determinant of health that goes beyond the major risk factors for diseases, like smoking or obesity, and may involve independent biological mechanisms. “One of the central objectives of the Lifepath project is to draw out the implications of the scientific findings for policy interventions to reduce inequalities”, comments

Richard Layte, professor of sociology at the Trinity College Dublin and one of the authors of the study. “Whilst social and economic disadvantage at any point in life is damaging to health, our findings suggest that policy should seek to protect the living standards of families with young children”.

While most policies targeted at poverty are focused on adults, such as the unemployed or workers with low incomes, some of them also cover infancy. Lifepath findings may thus have very important implications for public health policies, as they suggest that earlier interventions are likely to pay greater dividends than interventions later in life.