Education Linked to Lower Dementia Risk

Numerous studies have indicated that higher levels of education correlate with a reduced risk of Alzheimer’s disease. Additionally, remaining in school for a longer period has been associated with improved health and increased longevity.

However, most of this evidence is based on observational studies, making it tough to determine whether education directly causes the observed health benefits, or if other factors—like genetics, childhood experiences, or socioeconomic status—are at play.

“We’ve known for ages that people with more education have a lower likelihood of developing dementia, yet pinpointing whether education itself is the cause has been elusive,” says health economist Silvia Barcellos from the University of Wisconsin-Madison.

Recently, researchers identified, thanks to a significant legal change in the UK during the 1970s, what they believe to be the first evidence linking education directly to a lower incidence of dementia.

A new study featured in PNAS explored the long-term impacts of the 1972 Raising of School-Leaving Age Act (ROSLA). This act raised the minimum dropout age for students in England, Scotland, and Wales from 15 to 16.

The reform uniquely impacted students born after September 1, 1957, creating a distinct disconnection between education and birth date, as outlined by the researchers.

This specific cutoff date allowed for what could be termed a “natural experiment,” enabling a comparison between students who were required to stay in school until 16—now in their late sixties—and their peers who could leave at 15 before the switch took effect.

“This situation provided a valuable chance to examine the causal effects of education on the incidence of Alzheimer’s Disease and Related Dementias (ADRD),” the researchers noted in their paper.

If a causal relationship exists between education and ADRD, one would expect to see a distinct break in this relationship linked to birthdate at September 1, 1957. Essentially, individuals born right before and right after this date would likely have similar ADRD rates without the policy, suggesting any discrepancies arise from the educational changes.

In another recent study, researchers examined historical experiments, specifically looking into how strict sugar rationing during World War II affected babies’ health as they matured compared to those who weren’t subject to those limits.

Barcellos’ team also drew from the UK Biobank data for their research, and their findings seem to confirm the theory regarding education’s protective influence against dementia.

“Our results suggest that education negatively impacts ADRD incidence,” the researchers stated.

They observed a noticeable decline in ADRD incidence among individuals born after that pivotal date.

Their calculations suggested that extending schooling by just one additional year potentially lowered the ADRD incidence by about 0.88 percentage points—a figure the researchers admit could seem unrealistically high, given that the overall ADRD prevalence in the sample was under 1 percent.

While they suspect that statistical factors might account for this outlier, they maintain that the evidence supports a causal effect.

“Even though our sample is substantial, ADRD remains uncommon in these younger cohorts, and regression discontinuity designs require large samples for accurate estimates,” they emphasized.

“We can effectively evaluate the direction of the causal effect of education, but not its exact size.”

In addition to noting the lowered incidence of dementia among those born after that cutoff, the researchers also looked at study participants’ DNA to assess genetic risks, factoring in variations like the Alzheimer’s risk gene APOE4.

For individuals born before the change, those with a high genetic predisposition displayed a higher incidence of ADRD. However, for those born after, an extra year of schooling significantly reduced dementia rates, particularly in the high-risk group.

“For individuals aware of their greater genetic risk for dementia, this offers a hopeful perspective,” commented study co-author Leandro Carvalho, a health economist at the University of Southern California.

“While genes play a role in disease risk, they don’t invariably dictate outcomes.”

It’s still unclear precisely what aspect of that extra year of education provided these health benefits. Researchers propose it might relate to socioeconomic advantages gained from additional schooling, leading to better qualifications, income, and job status, which, over decades, could significantly protect against neurodegeneration—even among some at high risk.

There’s a lot we still don’t quite grasp, and it’s essential to acknowledge that these findings stem from specific historical conditions.

But there’s always the possibility that what happened could occur again.

“Our findings suggest that life experiences and circumstances that can be adjusted might influence whether inherited vulnerabilities lead to disease,” Carvalho noted.

“Understanding which interventions can facilitate these protective effects is a critical area for future studies.”

The results have been published in PNAS.