For example, middle-aged adults with the lowest 10% of wealth had about two
times the risk of stroke compared with those in the 75th-89th percentile, which
researchers say translates to the wealthy but not super-rich.
But the protective effect of wealth on stroke risk completely disappeared
after age 65.
"We expected wealth to be a strong predictor of stroke in the
elderly," researcher Mauricio Avendano, PhD, of the Erasmus Medical Center
in Rotterdam, Netherlands, says in a news release. "We were surprised
to see that it was not associated with stroke beyond age 65."
Wealth: A New Stroke Risk Factor?
Although previous studies have identified lower socioeconomic status as a
risk factor for stroke, researchers say this is the first study to look at how
factors that affect socioeconomic status, such as education, income, and
overall wealth, evolve throughout middle and old age.
In their study, published in Stroke: Journal of the American Heart
Association, researchers analyzed data from the Health and Retirement
study, which followed a group of nearly 20,000 Americans aged 50 or older for
an average of 8.5 years.
During the follow-up period, 1,542 participants had a stroke. The results
showed that higher education reduced stroke risk at ages 50 to 64 but not after
adjusting for wealth and income.
Both wealth and income were independent risk factors for stroke at ages 50
to 64. But wealth, including the total of all financial and housing assets
minus the liabilities, was a much stronger risk factor, with increasing wealth
linked to decreasing stroke risk.
"Wealth more comprehensively reflects both lifelong earnings and
intergenerational transfers, and increases access to medical care and other
material and psychosocial resources," Avendano says.
Beyond age 65, however, neither wealth, income, nor education was
significant predictors of stroke risk.
"We confirmed that lower wealth, education, and income are associated
with increased stroke up to age 65, and wealth is the strongest predictor of
stroke among the factors we looked at," Avendano says. "After age 65,
the association of education, income, and wealth with stroke are very weak, and
wealth did not clearly predict stroke."
Researchers say selective survival may explain some of these
effects: individuals with lower wealth die earlier than their richer
counterparts, and those that survive into old age are the healthiest.
"Further research is needed to understand why the effect of wealth,
income, and education on stroke is less clear beyond age 65 and the role of
selective survival," Avendano says.