Data from: Relation between 20-year income volatility and brain health in midlife: the CARDIA study

Objective: Income volatility presents a growing public health threat. To
our knowledge, no previous study examined the relationship between income
volatility, cognitive function and brain integrity. Methods: We studied
3,287 participants aged 23 to 35 years in 1990 from the Coronary Artery
Risk Development in Young Adults prospective cohort study. Income
volatility data were created using income data collected from 1990 to 2010
and defined as standard deviation of percent change in income and number
of income drops >=25% (categorized as 0, 1, or 2+). In 2010,
cognitive tests (n=3,287) and brain scans (n=716) were obtained. Results:
After covariate adjustment, higher income volatility was associated with
worse performances on processing speed (β=-1.09, 95%CI=-1.73, -0.44) and
executive functioning (β=2.53, 95%CI:0.60, 4.50) but not on verbal memory
(β=-0.02, 95%CI:-0.16, 0.11). Similarly, additional income drops were
associated with worse performances on processing speed and executive
functioning. Higher income volatility and more income drops were also
associated with worse microstructural integrity of total brain and total
white matter. All findings were similar when restricted to those with high
education, suggesting reverse causation may not explain these findings.
Conclusion: Income volatility over a 20-year period of formative earning
years was associated with worse cognitive function and brain integrity in
midlife.