Researchers collected income data over two decades for 3,287 adults, starting in 1990 when they were 23 to 35 years old. They assessed income volatility based on how much earnings rose or fell from one year to the next, and also tallied how many times participants' income dropped by at least 25%.

People who experienced greater income volatility and more pay cuts had worse scores for processing speed and executive functioning in cognitive tests in 2010. Brain scans that year also showed reduced connective white matter and worse structural integrity for people who experienced more income volatility and pay cuts.

"Overall, income volatility and unfavorable socioeconomic conditions may increase exposure to several risk factors of poor brain health," said Adina Zeki Al Hazzouri, a researcher at the Mailman School of Public Health at Columbia University in New York City.

"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," Zeki Al Hazzouri said by email. "In addition, they may have lower access to high-quality healthcare, which may result in worse management of these risk factors, and potentiate their impact on brain health."

Changes in cognitive test scores and brain scans didn't appear to differ when researchers only looked at participants with the most education.

Copyright Reuters, 2019