Taking a pay cut in your 30s could put you at risk of memory loss and poor brain function in middle age, research suggests.
Scientists assessed how changes in salary affected the brain health of more than 3,000 US adults.
The 20-year study began in 1990, and followed the participants through the Great Recession, a period of economic instability across the world.
Results showed volunteers whose pay had been slashed at least once over the two decades performed worse on cognitive tests.
The French researchers claim the impact of a pay cut on brain health was three times greater than that of one year of natural ageing.
They theorise that a person’s health generally deteriorates as a result of having less money than they once did.
Taking a pay cut in your 30s may put you at risk of memory loss and poor brain function in middle age, research suggests
The study, led by The Inserm Research Center in Bordeaux, followed 3,287 people. They were all 23 to 35 years old at the beginning.
Researchers tracked how often their income dropped, as well as the percentage of salary change between for each participant.
Participants fell into three groups – 1,108 (33.7 per cent) reported one drop of 25 per cent or more from their previous salary.
A further 399 people (12.1 per cent) had two or more such drops, and 1,780 people (54 per cent) 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.
For example, in one test, participants were shown a key that paired numbers one to nine with symbols.
All of the participants were then given a list of numbers and had to write down the corresponding symbols.
Researchers found volunteers who had two or more pay cuts performed worse than those whose salary didn’t change.
On average, their marks were 3.74 points lower – the equivalent of 2.8 per cent lower than their counterparts.
Data also showed volunteers 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.
Lead study author Dr Leslie Grasset, said: ‘For reference, this poor performance is greater than what is normally seen due to one year in aging.’
She said one year of ageing often leads to participants scoring worse by only 0.71 points, on average – around 0.53 percent.
Participants who endured more than two income drops scored even worse on how much time it took to complete some tasks.
There was no difference between the groups on tests that measured verbal memory – that is, remembering words you hear.
In a separate branch of the study, 707 participants also 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.
And volunteers who experienced one or more income drop had less white matter, which is tissue connecting different areas of the brain.
If white matter, made of nerve fibres, wastes away – normally due to disease – messages can’t pass through.
If a person has white matter disease, they will gradually have difficulty with the ability to think, balance and walk.
Previous research suggests the volume and weight of the brain declines as we age – by around five per cent per decade when a person reaches 40 years old.
Dr Grasset said: ‘Our exploratory study followed participants in the US 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.
‘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 US and many other countries.’
The academics suggested some indirect reasons for why an unstable income could influence brain health.
Dr Grasset said: ‘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 pick up unhealthy habits, such as drinking or smoking, or fail to manage diseases such as diabetes – which has many complications.
The study, published in Neurology, did not prove that drops in income cause poorer brain health, however.
Dr Grasset said further trials are needed to examine the role that social and financial factors play in brain ageing.
The study was limited because participants reported their income to researchers as falling within various income brackets, rather than specific figures.
