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Adam Rountree/AP Adam Rountree/AP

You’re allowed to be a bit of a mess in your 20s, right? You thought it would be character-building to chase your dream of being a musician and pick up catering work to make ends meet. Or maybe you came of age during a recession and couldn't find a steady job after getting laid off in your early 30s. Well, the bad news is that in addition to the hits your wallet took, by the time you reach middle age, the income volatility you experienced might have created negative consequences for your brain health.

A new study published in Neurology, the journal of the American Academy of Neurology, finds a correlation between an unstable income in your 20s and 30s and brain integrity in midlife.

Researchers at the University of Bordeaux; University of California, San Francisco; University of Miami; University College London; and Columbia University, found that greater income volatility and income drops, defined by the authors as decreases in income of 25 percent or more, were associated with worse performance in processing speed and executive functioning in midlife, as well as worse micro-structural integrity of total brain and total white matter. White matter coordinates communication between different brain regions and affects learning and other brain functions.

Higher income volatility and income drops in early-working years are associated with worse performance in processing and executive functioning in midlife.

This, of course has ramifications far beyond the middle-class college grads who spend their early years “finding themselves.” Racism, educational opportunity, and regional economic depressions contribute heavily to income volatility for young working people.

The study drew subjects from four cities: Birmingham, Alabama; Chicago, Illinois; Minneapolis, Minnesota; and Oakland, California. Over the period assessed—1990 to 2010—these cities generally had a high unemployment rate, averaging about 22 percent, compared to the national average of 3.6 percent, according to data from DataUSA.io. For 2019, the average minimum wage across the four cities is about $12 per hour, as per numbers pulled from the Economic Policy Institute’s minimum wage tracker.

Researchers collected income data from 3,287 black and white people of varied educational backgrounds (no other races or ethnicities were measured) who were age 18 to 30 when the study began. They are still tracking the participants who are all now in late midlife, making this one of few studies in the world that has measured nearly 30 years of repeated income information on a sample of the American population. A total of 1,780 (about 54 percent) participants did not have an income drop, while 1,108 (about 38 percent) had one drop of 25 percent or more from the previous reported income, and 399 (about 12 percent) had two or more income drops.

“By studying the sample over many years, we’re able to understand the life course,” said one of the authors on the study, Kristine Yaffe, professor of psychiatry, neurology, and epidemiology at UCSF. “We didn’t just want to look at people as a snapshot later in life.”

The brain health and functioning of the participants in the study were not measured when the study began in 1990, so it cannot be ruled out that low cognitive functioning might be a cause of income fluctuations for the subjects. But the study notes: “All findings were similar when restricted to those with high education, suggesting reverse causation may not explain these findings.”

It is well-documented that low socio-economic status has negative health consequences, like higher risk of dementia and cognitive problems. This study posits that the effects of income volatility early in life, which can have a measured outcome on brain functioning in midlife, present a growing health threat in the U.S., where more than a third of households experienced a 25 percent or more change in income between 2014 and 2015, according to a report by the Pew Charitable Trusts.

As Adina Zeki Al Hazzouri, study author and an assistant professor of epidemiology at Columbia University, told CityLab via email: “Cognitive impairment, decline, and ultimately dementia are public health priorities with tremendous health care costs.” And income volatility is likely to get worse as a quarter of American jobs will face high exposure to automation in the coming decades, according to a recent Brookings Institution report.

The Pew study also found that American families crave stability even more than upward mobility. As the 2020 presidential election draws near, candidates are attempting to address income inequality and income volatility in their platforms.

Democratic candidate Andrew Yang has been promising a Universal Basic Income (UBI) that guarantees a certain amount of money to every citizen without the rigamarole of passing tests, fulfilling work requirements, or dealing with bureaucracy. And to address income inequality, senator and candidate Elizabeth Warren has proposed an “ultra-millionaire tax plan” that aims to tax the richest households in a country where the top 1 percent of individuals hold 29 percent of the wealth, with plans to put the money generated towards universal healthcare and free college education.

Volatility has effects on the economy at large, according to a report by the Washington Center for Equitable Growth, because consumption of goods like food and clothing drops after workers lose their jobs. National health spending is projected to rise to almost a 20 percent share of the economy by 2025, thus making the relationship between something like brain health and income instability a bit of a vicious cycle.

“To me, it’s just another example that economic disadvantages have very far-flung consequences, including things we don’t think about, like the health of your brain,” said Yaffe.