Literacy Might Shield the Brain from Dementia

SCIENTIFIC AMERICAN
November 13, 2019
By Gary Stix

An ability to read and write, even with little or no schooling, could offer protection
 

Socrates famously railed against the evils of writing. The sage warned that it would “introduce forgetfulness into the soul of those who learn it: they will not practice using their memory because they will put their trust in writing.”

He got a few things wrong. For one, people nurture Socrates’ memory because of all of the books written about him. But he also was off the mark in his musings about a forgetfulness of the soul. If anything, it appears that just the opposite holds: a study of hundreds of illiterate people living at the northern end of an island considered to be a world media capital roundly contradicts the father of Western philosophy.

Evaluations of the elderly in the environs of Manhattan’s Washington Heights (the neighborhood immortalized by a Lin-Manuel Miranda musical) reveal that the very act of reading or writing—largely apart from any formal education—may help protect against the forgetfulness of dementia. “The people who were illiterate in the study developed dementia at an earlier age than people who were literate in the study,” says Jennifer J. Manly, senior author of the paper, which appeared on November 13 in Neurology.

Earlier studies trying to parse this topic had not been able to disentangle the role of reading and writing from schooling to determine whether literacy, by itself, could be a pivotal factor safeguarding people against dementia later in life. The researchers conducting the new study, who are mostly at Columbia University’s Vagelos College of Physicians and Surgeons, recruited 983 people with four years or less of schooling who were part of the renowned Washington Heights–Inwood Columbia Community Aging Project. Of that group, 238 were illiterate, which was determined by asking the participants point-blank, “Did you ever learn to read or write?”—followed by reading tests administered to a subsample. Even without much time in school, study subjects sometimes learned from other family members.

The average age of the illiterate group was about 78, and many had come from rural parts of the Dominican Republic, which had experienced the legacy of midcentury  strongman Rafael Trujillo’s educational neglect. Smug assumptions cannot be made about universal literacy: the Department of Education estimates there are 32 million adults in the U.S. who are illiterate.

In the Washington Heights study, 35 percent of the illiterate group (82 of 238) had dementia when the study began, as against 18 percent (137 of 743) of literate participants. Multiple follow-ups occurred: the average interval was four years, and data were gathered as far back as 23 years. Of the 155 illiterate people who did not have dementia when first examined, 48 percent were diagnosed with it upon follow-up, whereas 27 percent of the 609 such individuals in the literate group were no longer dementia-free.

The researchers found that literacy was linked to higher scores on cognitive measures not solely tied to reading or language skills. And other research has discovered more gray matter and other beneficial changes in the literate brain. Separately, it surprised the new study’s team that the rate of cognitive decline did not differ between the literate and illiterate groups—perhaps because the illiterate segment, when first examined, was already closer to meeting dementia thresholds. Also, the dementia risk posed by illiteracy was the same for men and women, unlike in some earlier investigations that tilted toward a higher peril for women.

Heather M. Snyder, vice president of medical and scientific relations at the Alzheimer’s Association, says this study will add to the literature on “life-course contributions” as a means to diminish dementia risk, adding that factors other than literacy must be taken into account. “I think it will be really important to take this study, which is a nicely done study in a large number of individuals, and really understand what are some of the other factors that might be at play for these individuals,” she says.

The paper raises an obvious idea for future research: “Could we change and lower that dementia risk by intervening at midlife or later life by helping people to learn to read and write?” says Miguel Arce Rentería, the first author of the study. “That’s an empirical question.”

The benefits of pushing forward become immediately obvious when contemplating what, exactly, is going on when a person processes words. In her book Proust and the Squid: The Story and Science of the Reading Brain, cognitive scientist Maryanne Wolf writes that learning to read entails “an amazing panoply of phonological, semantic, syntactic, morphological, pragmatic, conceptual, social, affective, articulatory, and motor systems, and the ability of these systems to become integrated and synchronized into increasingly fluent comprehension.” Forget brain games—just read a good book.

Also covered by: The New York Times.