People who take a pay cut in their 30s could be at a higher risk of memory loss and poor brain function in middle age, research suggests.
The 20-year study of 3,000 US adults, which began in 1990, found people whose pay had been slashed at least once over the two decades performed worse on cognitive tests.
The French researchers claimed the impact of a pay cut on brain health was three times greater than that of one year of natural ageing.
The study, led by The Inserm Research Center in Bordeaux, put the participants into three groups: 1,108 people (33.7%) reported one drop of 25% or more from their previous salary; 399 people (12.1%) had two or more such drops; and 1,780 people (54%) did not have any income drop.
At the end of the study, participants were given thinking and memory tests that measured how well they completed tasks and how much time it took to complete them.
Volunteers who had two or more pay cuts performed worse than those whose salary did not change. On average, their marks were 3.74 points lower – the equivalent of 2.8% lower than their counterparts. Those who experienced one pay cut scored 2.87 points lower than those whose salary didn’t change.
The results remained true after experts adjusted for other factors that could affect thinking skills, such as high blood pressure and education level, according to the study reported by the Daily Mail.
Lead study author Dr Leslie Grasset said one year of ageing often leads to participants scoring worse by only 0.71 points on average – around 0.53%.
In a separate branch of the study, 707 participants had brain scans with MRI at the beginning and end of the study to measure their brain volume. People with two or more income drops had smaller total brain volume, compared to those whose salary stayed consistent.
Volunteers who experienced one or more income drop had less white matter.
“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,” said Grasset. “Income volatility is at a record level since the 1980s and there is growing evidence that it may have pervasive effects on health.”
Grasset suggested that individuals who experience important income fluctuations may be more at risk for cardiovascular risk factors, depression, or perceived stress, which are in turn associated with poor cognitive health.
Those with financial instability may also pick up unhealthy habits, such as drinking or smoking, or fail to manage diseases such as diabetes.
The study, published in Neurology, did not prove that drops in income cause poorer brain health.