Sustained Economic Hardship May Affect Cognitive Function at Middle Age

Persistent low income in young adulthood and middle age may raise the risk for worse cognitive function by age 50, according to a study of more than 3300 adults who were followed for more than 2 decades. In addition, the study suggested that poverty and perceived hardship may be important contributors to premature aging among disadvantaged populations. The study, by Adina Zeki Al Hazzouri, PhD, of the University of Miami, and colleagues, was published in the American Journal of Preventive Medicine.

Previous research has shown that exposure to poor socioeconomic conditions in childhood and adulthood is associated with cognitive deficits, but most studies have involved older adults, the authors noted. In contrast, this study examined whether economic adversity impacts cognitive health earlier in the live course.

Income data were collected 6 times between 1985 and 2010 for 3383 adults enrolled in the Coronary Artery Risk Development in Young Adults prospective cohort study. Participants were aged 18 to 30 at recruitment. In 2010, at a mean age of 50 years, participants underwent a cognitive battery of tests. There were no cognitive studies at baseline. Study subjects were asked about the amount of time they spent in poverty (defined as less than 200% of the federal poverty level, an annual income of $44,630 for a 4-person household in 2010). The subjects could choose from “never in poverty,” “never to less than one-third of the time,” “one-third of the time or more to less than 100% of the time,” or in poverty “all the time.”

The study found that participants whose income was in the “all of the time” poverty bracket had lower cognitive scores than those who had never been in poverty. They scored an average of 0.92 points less on verbal memory (range, 0 to 15), 11.60 points less on processing speed (range, 8 to 125), and slightly lower on a test that measured the ability to respond to some stimuli while repressing others. Similar results were seen with perceived financial difficulty.

“Maintaining cognitive abilities is a key component of health,” Zeki Al Hazzouri said in a statement. “Findings from this relatively young cohort place economic hardship as being on the pathway to cognitive aging and as an important contributor to premature aging among economically disadvantaged populations.”

The researchers pointed out that small differences at age 50 may lead to bigger differences later on. The findings reveal a graded relationship such that cognitive performance, and processing speed in particular, was worse with cumulative exposure to economic adversity.

What do those differences at age 50 mean over time?

“If there is a small difference at age 50, there may be a significant difference later in life,” said study coauthor Kristine Yaffe, MD, of the University of California San Francisco. “It’s important that those in long-term poverty are followed with a view to possible interventions.”