October 30, 2019
Big drops in income in young adulthood may impair brain health decades later, according to a new report. The findings suggest that a wide variety of factors, including social and financial circumstances, may play role in brain aging.
For the study, researchers followed 3,287 racially diverse Americans who ranged in age from 23 to 35 at the study’s start, in 1990. All were part of the ongoing Coronary Artery Risk Development in Young Adults (CARDIA) trial.
Study participants reported their annual income every three to five years over the next 20 years, through 2010. The researchers ranked them according to how often they had drops in income of 25 percent or more. Among the study group, more than half, or 1,780, did not have an income drop; about a third, or 1,108, had one drop of 25 percent or more during these years; and 399 had two or more such significant drops.
Participants also completed tests of thinking and memory skills. In one test, for example, they were shown a list of symbols that were paired with numbers 1 through 9. They then had to remember the list and match numbers with the correct symbol.
The researchers found that people with two or more income drops performed worse in completing tasks than people with no income drops. The more income declines a person had, the worse his or her performance on tests of processing speed, planning and organization.
“For reference, this poor performance is greater than what is normally seen due to one year in aging,” said Leslie Grasset of the Inserm Research Center in Bordeaux, France, one of the study authors. The researchers controlled for various factors that can affect thinking skills, such as high blood pressure, education level, physical activity and smoking.
Among the study group, some of the participants also had MRI brain scans at the start of the study, and again 20 years later. Researchers found when compared to people with no income drops, people with two or more income drops had a smaller total brain volume. Smaller brain volume has been tied to an increased risk of developing Alzheimer’s disease and other forms of dementia later in life.
People with one or more income drops also had fewer connections between cells in different areas of the brain. Increased brain connectivity is thought to protect against memory loss and other symptoms of dementia.
The study was preliminary, and more research is needed to confirm the findings. But this is one of the first studies to examine the relationship between income and brain health. The findings were published in Neurology, the medical journal of the American Academy of Neurology.
“Our exploratory study followed participants in the United States through the recession in the late 2000s, when many people experienced economic instability,” said Dr. Grasset. “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 authors note that the study does not prove cause and effect, but there may be several reasons why income instability may affect brain health, including reduced access to medical care and poor management of diseases like diabetes, which has been linked to an increased risk of Alzheimer’s disease. Of course, stress and other psychological factors related to income drops could also play a role in brain aging.
The authors note ” it’s possible that income stability could play a beneficial role in brain health.”
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Marc Flajolet, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.
Source: Leslie Grasset, PhD, M. Maria Glymour, ScD, Tali Elfassy, PhD, et al: “Relation between 20-year income volatility and brain health in midlife: The CARDIA study.” Neurology, Oct. 2, 2019