A National Institutes of Health (NIH)-funded study has found that an extra year of compulsory secondary schooling reduced dementia diagnoses up to 50 years later, according to the official release. The analysis, led by researchers at the University of Wisconsin–Madison and the University of Southern California, Los Angeles, found the benefit was largest among people whose genetics placed them at elevated risk for Alzheimer's Disease and AD-Related Dementias (ADRD).

What the Study Measured

The research team examined a 1972 education reform enacted in England, Wales, and Scotland that raised the minimum age at which students could leave school from 15 to 16, affecting anyone born after Sept. 1, 1957. According to NIH, the change produced a 14% increase in the number of students who remained enrolled until age 16, creating a natural comparison group of students who were and were not subject to the new rule.

To measure the long-term health effects of that extra year, the researchers analyzed medical data from more than 100,000 participants in the UK Biobank, a large aging cohort. Diagnoses recorded before December 2022, when the oldest participants in the study turned 65, served as the primary basis for comparing those affected by the reform against those who were not.

To reduce the risk that the results were skewed toward people healthy enough to seek and receive a diagnosis, the researchers pulled diagnostic information from multiple sources, including medical histories, hospital records, and death registries, per the NIH release.

The Headline Numbers

NIH described the 0.88% reduction in dementia incidence as "a considerably large effect given that overall rates of dementia in the study population were low." The agency noted the effect was not uniform across participants: it was strongest among those carrying specific genetic variants already known to raise the risk of AD/ADRD, suggesting education may do more to offset inherited vulnerability than to shift outcomes for people with average genetic risk.

Why a Law From 1972 Became a Research Tool

Scientists have long observed a correlation between higher education levels and lower dementia risk, but establishing that the relationship is causal, rather than simply reflecting other differences between more- and less-educated people, requires comparing an intervention against a control group across a large population followed over many years. The UK's 1972 school-leaving age reform gave researchers exactly that kind of natural experiment, because it changed enrollment rules based solely on a student's birth date rather than any individual choice or trait.

Richard Hodes, M.D., director of NIH's National Institute on Aging (NIA), said in the release that "these findings reinforce the understanding that dementia risk is determined by factors beyond one's genetic makeup and that changes such as additional schooling can offset inherited vulnerability." The study also tied the reform to improvements in socioeconomic factors and other areas of health, which NIH said may point to some of the pathways through which education affects dementia risk.

What the NIA Does and How This Research Fits In

NIA, the NIH institute that funded the research, describes its mission as understanding the nature of aging and diseases associated with growing older, with the goal of extending healthy, active years of life. NIH itself is the United States' primary federal agency for conducting and supporting basic, clinical, and translational medical research, operating through 27 institutes and centers under the U.S. Department of Health and Human Services.

This study was supported through five separate NIA grants, numbers R01AG078522, K01AG0669991, RF1AG055654, R56AG058726, and R00AG062787, underscoring how federally funded basic research can take advantage of policy changes in other countries, such as the UK's school-leaving law, to answer questions about disease prevention that would be difficult or impossible to test through a traditional clinical trial. The findings were published in the Proceedings of the National Academy of Sciences on October 23, 2026.

Limits Acknowledged by the Researchers

The study's authors cautioned against over-reading the precise size of the effect, noting that participant age was capped at 65 in the current analysis. As the UK Biobank cohort continues to age and dementia diagnoses become more common, NIH noted that differences between the group affected by the reform and the unaffected group could grow larger or smaller over time.

Lead author Silvia Barcellos, Ph.D., a health economist at the University of Wisconsin–Madison, said in the release: "The message here is less about the specific numbers and more about the nature of education's connection to dementia. There are few preventative options out there so even one could make a world of difference."

Frequently asked questions

What exactly did the UK's 1972 law change?

The law raised the minimum age at which students in England, Wales, and Scotland could leave school from 15 to 16, applying to anyone born after Sept. 1, 1957. NIH reported this produced a 14% increase in the number of students who stayed enrolled until age 16.

How big was the reduction in dementia risk?

The researchers found that the additional year of schooling reduced Alzheimer's Disease and AD-Related Dementias incidence over the following 50 years by 0.88%, which NIH described as a considerably large effect given the low overall dementia rates in the study population.

Who benefited most from the extra year of school?

According to the release, the effect was strongest among study participants carrying specific genetic variants known to increase the risk of Alzheimer's Disease and AD-Related Dementias, suggesting education may particularly help offset inherited genetic risk.

Why do the researchers urge caution about the results?

The analysis capped participant age at 65 as of December 2022, and the study's authors noted that as the UK Biobank cohort ages and more dementia diagnoses occur, the measured differences between groups could change in either direction.