What the researchers say
“Income volatility is at a record level and there is growing evidence that it may have pervasive effects on health, yet policies intending to smooth unpredictable income changes are being weakened in the United States and many other countries,” said the study’s lead author. “Our study followed participants in the United States through the recession in the late 2000s when many people experienced economic instability. Our results provide evidence that higher income volatility and more income drops during peak earning years are linked to unhealthy brain aging in middle age.”
The study involved 3,287 people who were 23 to 35 years old at the start of the study and were enrolled in the Coronary Artery Risk Development in Young Adults (CARDIA) study, which includes a racially diverse population. Participants reported their annual pre-tax household income every three to five years for 20 years, from 1990 to 2010.
Researchers examined how often income dropped as well as the percentage of change in income between 1990 and 2010 for each participant. Based on the number of income drops, participants fell into three groups: 1,780 people who did not have an income drop; 1,108 who had one drop of 25 percent or more from the previous reported income; and 399 people who had two or more such drops.
Participants were given thinking and memory tests that measured how well they completed tasks and how much time it took to complete them. Researchers found that people with two or more income drops had worse performances in completing tasks than people with no income drops. On average, they scored worse by 3.74 points or 2.8 percent.
“For reference, this poor performance is greater than what is normally seen due to one year in aging, which is equivalent to scoring worse by only 0.71 points on average or 0.53 percent”, said the researchers.
The results were the same after researchers adjusted for other factors that could affect thinking skills, such as high blood pressure, education level, physical activity and smoking.
Of the study group, 707 participants also had brain scans with magnetic resonance imaging (MRI) at the beginning of the study and 20 years later to measure their total brain volume as well as the volumes of various areas of the brain.
Researchers found when compared to people with no income drops, people with two or more income drops had smaller total brain volume. People with one or more income drops also had reduced connectivity in the brain, meaning there were fewer connections between different areas of the brain.
The study reinforces several things that we already knew, for example income is related to status. When we experience a fall in income, we also experience a fall in self-perceived status and self-esteem. This has a nasty effect on both our psychic and physical immune systems. If we perceive ourselves as less valuable our mental performance goes down. And we can become ill – sometimes very ill.
We also tend to look after ourselves less and our relationships become shakier. We also make worse decisions.
The other problem with income loss is that it often happens after a person is laid off or is made redundant. Studies have shown that if you are sacked, laid off or made redundant more than three times in your life (especially in the years under study) you are very likely to suffer a heart attack even decades later – as are your children!