Young adults who experience drops in income have smaller brains in middle age

New research shows that people dealt two or more blows to their income had worsened thinking abilities and poorer brain health years later.

BORDEAUX, France– Everyone knows a pay cut or demotion at work is going to lead to a tighter budget and more financial worries, but a new international study finds that drops in income may also cause cognitive issues. According to researchers at the Inserm Research Center in Bordeaux, France, young adults who face annual income drops of 25% or more may be at a greater risk of developing thinking problems and diminished brain health later on in life.

“Income volatility is at a record level since the 1980s 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,” says study author Dr. Leslie Grasset, of the Inserm Research Center, in a statement. “Our exploratory 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.”

In all, 3,287 people between the ages of 23-35 took part in the study. The population sample used was racially diverse, and each person reported their annual pre-tax household income every three to five years for a total of 20 years (1990-2010).

The research team kept an eye out for how often each participant’s income dropped, as well as individual changes in income percentages between 1990-2010. Using this data, participants were separated into three groups: those who did not experience an income drop (1,780 people), those who had one drop of 25% or more compared to their previously reported income (1,108 people), and those who experienced two or more significant drops (399 people).

Then, each participant was given thinking and memory tests designed to measure how quickly and efficiently they could successfully complete a task. One test involved using a guide that paired the numbers 1-9 with specific symbols, after studying the guide participants were given a list of numbers and asked to recall their corresponding symbols.

Interestingly, participants who experienced two or more income drops performed significantly worse on the tasks than those with no income drops. On average, the two or more income drop group scored 3.74 points (2.8%) worse.

“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,” Dr. Grasset explains.

Furthermore, participants within the group that experienced two or more income drops also took longer than others to complete the tasks. There was, however, no differences between the three groups regarding verbal memory tests. These findings were consistent even after researchers accounted for other factors that may impact thinking skills, such as individual education level and physical activity.

Additionally, 707 of the 3,287 study participants also had MRI brain scans at the beginning of the study in 1990, and then again in 2010 in order to assess how their total brain volume, as well as the volume of specific brain areas, had changed over the years. After analyzing these brain scans, it was noted that people with two or more income drops actually had smaller total brain volume compared to the other groups. Participants with at least one income drop also displayed reduced brain connectivity.

“There may be several explanations as to why an unstable income may have an influence on brain health, including that people with a lower or unstable income may have reduced access to high quality health care which may result in worse management of diseases like diabetes, or management of unhealthy behaviors such as smoking and drinking,” Dr. Grasset comments. “While our study does not prove that drops in income cause reduced brain health, it does reinforce the need for additional studies examining the role that social and financial factors play in brain aging. It is possible that enhancing the stability of income could play a beneficial role in brain health, and there are straightforward policy options to reduce income volatility, such as unemployment insurance and short-term wage insurance.”

The study was limited by the fact that participants reported their income to researchers via broad income brackets, meaning exact dollar amounts could not be verified.

This study is published in the scientific journal Neurology.