Northwestern University researchers show this association is unlikely to be merely an artifact of early experiences or heritable traits shared by families(William_Potter | iStock)
· In 5414 American participants, those who had accumulated a higher net worth by midlife had significantly lower mortality risk over the subsequent 24 years.
· Findings from analyses of siblings and twins suggested that wealth accumulation at midlife may be associated with longevity among adults in the United States.
It turns out that your net worth at midlife is linked to your longevity, according to new research published in JAMA Health Forum, at least among Americans. Finegood and colleagues from Northwestern University dug into data from the Midlife in the United States study (MIDUS) — a cohort study of 5414 participants aged 20 to 75 that lasted over 24 years. They found that Americans that had accumulated a higher net worth by midlife had significantly lower mortality risk.
Finegood and colleagues propose, “Policies that support individuals’ ability to accrue wealth and achieve financial security could have considerable health benefits. In addition, policies to reduce the wealth gap may generate substantial returns to public health.”
This study isn’t the first time that researchers have tried to pin financial wealth to lifespan. Studies have shown that net worth is more strongly associated with mortality than other indicators of socioeconomic status, such as occupational prestige, educational attainment, and income.
However, these studies can be filled with confounding factors, such as our childhood environments and heritable traits. These confounding factors could simultaneously affect socioeconomic conditions in adulthood and health in the course of life.
The way to address these confounders is for researchers to look at siblings raised in the same family. These individuals share much of their early rearing environment and are genetically related to one another. So, when comparing siblings, factors that are shared are accounted for.
Comparisons of twins provide even greater control of family-level early-life confounders. In the case of monozygotic twins, you can even account for heritable genetic factors. Twin studies have shown that occupational prestige and educational attainment are associated with better adult health outcomes and longevity.
Finegood and colleagues looked at the link between wealth and longevity in individuals, siblings, and twin pairs. Specifically, they examined the association between net worth at midlife (the middle years of life) and subsequent all-cause mortality.
The entire study consisted of 5414 participants with an average age of 46.7 years. Just over half were women (51.1%). Finegood and colleagues found that higher net worth was associated with lower mortality risk across all these individuals.
The Northwestern University researchers also probed whether the wealth-longevity association was primarily driven by common factors at the family level, like early experiences or heritable factors. To do so, they looked at siblings and twin pairs.
Finegood and colleagues similarly observed this link between net worth and longevity within families among siblings and twin pairs; a sibling or twin with more wealth tended to live longer than their co-sibling or co-twin with less wealth.
A difference of $139 000 in net worth was associated with a 13% relative decrease in the probability of death nearly 24 years later, favoring the family member with a higher net worth; given the low base rate of mortality in the sample, this decrease translated into more than a 1% absolute difference in survival.
But when Finegood and colleagues performed separate estimates for the subsamples of siblings, dizygotic twins, and monozygotic twins, the within-family estimates of the net worth–mortality association were similar but weaker. The Northwestern University researchers think this is likely due to the substantial decrease in the sample size and the number of deaths within each twin subsample.
“The within-family association provides strong evidence that an association between wealth accumulation and life expectancy exists because comparing siblings within the same family to each other controls for all of the life experience and biology that they share,” said lead author Eric Finegood, a postdoctoral fellow in the Institute for Policy Research at Northwestern.
Bridging the wealth gap
In the United States, wealth inequality is growing faster than income inequality. Over the past 30 years, the wealth gap between the high-income and low-income people in the US has widened.
Policies and practices have diverted a substantial and increasing share of wealth from the lower- and middle-income groups to the affluent group. Such redistribution may have implications for longevity patterns in the coming decades.
People with greater wealth have better access to health-promoting resources like medical care, safe places to exercise, and fresh foods. Wealthy individuals also have more protection from economic shocks, such as job loss, unexpected health care expenses, or other financial crises.
The association between wealth and longevity has become more relevant in the past year. The economic fallout from the COVID-19 pandemic has disproportionately affected the financial security of low-income and older workers.
The findings of this JAMA Health Forum study suggest that policies to support individuals’ ability to accrue wealth and achieve financial security in adulthood could have considerable health benefits. These kinds of policies could be impactful in the US, which ranks first in economic inequality among high-income nations.
“Far too many American families are living paycheck to paycheck with little to no financial savings to draw on in times of need,” said the study’s senior author Greg Miller, the Louis W. Menk Professor of Psychology and faculty fellow at the Institute for Policy Research at Northwestern.
“At the same time, wealth inequality has skyrocketed. Our results suggest that building wealth is important for health at the individual level, even after accounting for where one starts out in life. So, from a public health perspective, policies that support and protect individuals’ ability to achieve financial security are needed.”