(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 b