Past studies have suggested that higher education levels are linked to a lower risk of Alzheimer’s disease, and that staying in school for longer is associated with benefits to health and longevity too, reports Science Alert.
Now, thanks to a landmark legal reform that took place in the UK in the 1970s, researchers have identified what they believe is the first evidence of its kind demonstrating a causal link between education and reduced dementia incidence.
Previously, all of the evidence for this came from observational studies, so it was hard to know for sure whether education causes the positive health effects we see, or if other explanations drive the changes – like genetics, childhood circumstances, or socioeconomic factors.
“We have known for a long time that people with more education are less likely to develop dementia, but until now, it has been difficult to know whether education itself is responsible,” said health economist Silvia Barcellos from the University of Wisconsin-Madison.
In a study published in PNAS, Barcellos and fellow researchers investigated the long-term effects of the 1972 Raising of School-Leaving Age Act (ROSLA), which increased the minimum age at which students could drop out of school in England, Scotland, and Wales, raising it from 15 to 16-years-old.
"The reform affected only students born after 1 September 1957, generating a discontinuity in the relationship between education and date of birth,” the researchers wrote.
That strict cut-off date created the conditions for a “natural experiment”, enabling the study team to compare the subsequent health in later life of students who had to stay in school until 16 (the “treated” students, who are now in their late 60s) with that of their peers from directly before the change took effect, who could leave school at 15 (the “control” group).
“This setting provided a unique opportunity to study the causal effects of education on Alzheimer’s Disease and Related Dementias (ADRD) incidence,” the researchers said.
“If, as hypothesised, there is a causal relationship between education and ADRD, then one would expect to observe a corresponding discontinuity in the relationship between ADRD and date of birth at 1 September 1957.
“Because individuals born right before and right after this date would have had similar ADRD incidence in the absence of the policy, any observed discontinuity could be attributed to the difference in schooling engendered by the policy.”
Their findings indicate that education has a negative causal effect on ADRD incidence, the researchers write.
“There is a sharp decline in ADRD cumulative incidence among those born after 1 September 1957.”
In the researchers’ calculations – they used data from the UK Biobank – the effects of staying in school for one year longer reduced ADRD cumulative incidence in the cohort by 0.88 percentage points – an effect that the team acknowledges is implausibly large, given that the prevalence of ADRD in the sample was lower than 1% overall.
They suggest the anomalous result might be due to statistical factors, but while they say they can’t provide an entirely accurate estimate of the extent of the reduction in dementia cases, they say the evidence supports a causal effect.
“Although our sample is large, ADRD remains a rare outcome in these relatively young cohorts, and regression discontinuity designs require very large samples to achieve precise estimates,” they write.
“We can credibly estimate the direction of the causal effect of education, but not its precise magnitude.”
In addition to measuring the reduced incidence of dementia in children born after 1 September 1957, the researchers also examined DNA from the study participants, sorting them into high risk or low risk for ADRD based on whether they had certain genetic variations, including the Alzheimer’s risk gene APOE4.
For children born before the school dropout age changed, individuals with high genetic risk experienced significantly greater incidence of ADRD, but among those born after the change, the extra year of schooling was associated with a significant reduction in dementia incidence in the high-risk group.
“For people who know they have a higher genetic risk of dementia, this is a hopeful finding,” said study co-author Leandro Carvalho, a health economist at the University of Southern California.
“Genes help shape disease risk, but they do not necessarily determine the outcome.”
While we can’t know for sure what it was about that extra year of education that delivered the health benefits, the researchers suggest it could have been due to socioeconomic advantages produced by additional schooling, which may have elevated their school qualifications, income, and occupational status.
Compounded over a half-century, those advantages might have added up considerably, conferring protection against neurodegeneration, even in some high-risk individuals.
There’s still a lot we don’t fully understand, and it’s worth noting that the findings here stem from unique historical circumstances.
But if it happened once, maybe it can happen again.
“Our results suggest that experiences and circumstances that can be changed over the course of life may influence whether inherited susceptibility ultimately translates into disease,” Carvalho says.
“Understanding which interventions can produce these protective effects is an important direction for future research.”
Study details
Education reduces dementia incidence and mitigates genetic risk
Silvia Barcellos, Leandro Carvalho, Kenneth Langa, and Patrick Turley.
Published in PNAS on 23 October 2026
Significance
Scholars have noted the need for high-quality evidence on which factors can reduce Alzheimer’s Disease and Related Dementias (ADRD) and delay its onset. Such evidence is paramount for designing policies that can prevent and effectively treat dementia. Characteristics that are highly associated with ADRD risk have been deemed as risk factors for dementia, but there is limited evidence as to whether these characteristics causally affect ADRD. We document a causal relationship between education and ADRD diagnosis.
Abstract
There is little causal evidence on factors that can protect individuals against Alzheimer’s Disease and Related Dementias (ADRD) risk. We study the causal effect of education on ADRD, exploiting a regression discontinuity generated by a compulsory schooling reform. ADRD was ascertained based on medical history, hospital records, and death registries, addressing concerns about selective sample attrition. We find that education reduces incidence of ADRD. Using molecular genetic data, we show that the reform weakened the relationship between genetics and ADRD incidence, implying genetic risk of dementia is not immutable and can be modified by social policy.
PNAS article – Education reduces dementia incidence and mitigates genetic risk (Open access)
See more from MedicalBrief archives:
Cognitively active lifestyle may delay onset of Alzheimer's dementia by five years
Alzheimer’s risk factors may be detected before 30 – US study
Education trumps heart health for memory in older people – Helsinki study