(CNN)Whether or not you can read and write could be a factor in your ability to stave off dementia as you grow older, according to a new study from scientists at Columbia University.
They published their results Wednesday in the online issue of the journal Neurology.
Researchers studied 983 adults over age 65 living in New York City's Washington Heights area who had four or less years of schooling.
Visiting the participants' homes, the scientists performed tests of the memory, language and visual or spatial abilities. During those visits, they made dementia diagnoses based on the standard criteria.
The illiterate participants performed worse on those tests.
In establishing the baseline measures, those who had never learned to read or write were nearly three times as likely to have dementia than those who could read.
And among those who didn't have dementia at the beginning of the study, the illiterate section of the cohort was twice as likely to develop it.
One reason for the brain decline, the authors write, is that those who don't learn to read have "a lower range of cognitive function" than those who are literate.
The findings are part of a long term study on aging
Jennifer Manly, a neuropsychology professor at Columbia University and the senior author on the study, told CNN that scientists have been monitoring a cohort of adults over age 65, many from diverse backgrounds in the Washington Heights area, since 1992.
Over the past three decades, they've studied 6,500 New Yorkers as they've aged, she said.
While it's long been known that educational attainment can be tied to better health outcomes, a major goal of the study was to determine how literacy can or cannot correlate with someone's ability to maintain brain health during their golden years.
For instance, many of the illiterate adults in Washington Heights came from the Dominican Republic, she said, and may have had to drop out of school to work.
She says more research is needed to corroborate her team's findings, but they could build a public health case for those who quit schooling early to be enrolled into adult literacy courses to help maintain protections against dementia.
Policymakers should take note, a scientist says
Manly said the study had implications for how nations think about their educational policy.
"The reason they didn't go to school was due to Dominican education policy," she said.
After the eighth grade, school attendance is no longer mandatory in the Dominican Republic, according to the non-profit Borgen Project.
Manly said that in the US, policymakers should reckon with the fact that "educational quality shapes later life brain health."
"Increasing opportunities for children and adults to obtain literacy may be protective for brain health later in life," she said.
Manly likened the positive effects that learning to read can have on the mind to the positive effects that exercise can have on the body.
"For individuals and families, health behaviors should include education," she said.