A rather novel bit of research has recently been released that shows the culmination of a 25-year effort to see whether poverty and perceived economic hardship play a role in cognitive function. It was found that there was a marked increase in cognitive deficits, which the researchers interpreted as marking economic hardship as a contributor to premature aging. The findings support this idea, in part, but the details make it a bit harder to determine.
The research started back in 1985-86 when 3,383 adults (male, female, white, and black) between ages 18 and 30 were recruited. Income data for the participants was collected six times, and the participants were examined at baseline and at the two, five, seven, 10, 15, 20, and 25-year mark. At the year 25 follow-up, cognitive function was assessed using three established tests. The participants were also divided by how much time they spent in what the researchers dubbed “sustained poverty”—periods where household income was less than 200% of the federal poverty level. The four groups were as follows: never in poverty, less than a third of the time in poverty, between a third and 100% of the time in poverty, and always in poverty.
It was found that there was a significant and graded (“dose-response”) relationship between poverty and cognitive function over the 25-year period. The longer participants spent in poverty and the stronger their perceived hardship, the worse they performed on the tests. This effect was highest among tests for processing speed. In order to make sure education wasn’t an influence, a subgroup analysis was performed on the most highly-educated participants, but the overall trend remained the same. This suggests to the researchers that young people who grow up in poor socioeconomic conditions can face cognitive deficits when they reach adulthood. It was posited that this might help explain why signs of premature aging are more common among lower income levels.
One downside of the study, which the authors acknowledge, is that they only have cognitive data from the 25th year. This means they have no baseline comparison or measurements of progress. Without this piece of data, it’s possible that the strength of the correlation is not as strong as it appears.
What This Means
It’s hard to pin down what these findings might mean for the simple reason that they are covering a correlation rather than a causative relationship. Low income levels are associated with increased stress, worse access to nutrition, poorer healthcare, and higher rates of unhealthy behaviors like smoking or lack of exercise. It is likely that these and similar effects are driving the findings. The definition of “premature aging” used in this study is also somewhat vague and seems to be tied purely to cognitive performance rather than actual physical or biological markers.
Basically, although economic hardship is associated with poorer cognitive health, the relationship is indirect and makes the value of using income for assessing premature aging uncertain at best.
Al Hazzouri, A., et. al., “Sustained Economic Hardship and Cognitive Function: The Coronary Artery Risk Development in Young Adults Study,” American Journal of Preventive Medicine, 2016; http://dx.doi.org/10.1016/j.amepre.2016.08.009.