A 1970s legal reform in the UK that raised the minimum school-leaving age from 15 to 16 has provided researchers with new evidence of a causal link between education and reduced Alzheimer’s disease and related dementias, according to a study published in PNAS.
Higher education levels have long been associated with a lower risk of Alzheimer’s disease, alongside benefits to health and longevity. However, because nearly all supporting evidence previously came from observational studies, health experts struggled to confirm whether education itself directly drove these positive health outcomes or if other factors like genetics, childhood circumstances, or socioeconomic background were responsible.
We have known for a long time that people with more education are less likely to develop dementia, but it has been difficult to know whether education itself is responsible,
explains health economist Silvia Barcellos from the University of Wisconsin-Madison.
The 1972 Raising of School-Leaving Age Act
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Researchers investigated the long-term effects of the 1972 Raising of School-Leaving Age Act (ROSLA), which increased the dropout age in England, Scotland, and Wales from 15 to 16 years old. The reform affected students born after September 1, 1957. This strict cutoff date created a natural experiment, allowing researchers to compare the later health of students who stayed in school until 16—referred to as treated students now in their late sixties—with peers born right before the change who could leave at 15.
A 1972 UK law raising the school-leaving age to 16 became a 50-year dementia experiment. Comparing 100,000+ people born either side of 1 Sep 1957, a new PNAS study found the extra year cut diagnoses before 65, most in those at high genetic risk. No drug trial runs that long. pic.twitter.com/TSyTQRsAe4
By drawing on UK Biobank data, Barcellos and her fellow researchers observed a sharp decline in Alzheimer’s Disease and Related Dementias cumulative incidence among individuals born after the September 1, 1957 threshold. Calculations indicated that staying in school for one year longer reduced cumulative incidence in the cohort by approximately 0.88 percentage points. While the research team acknowledges this numerical estimate is implausibly large given that overall sample prevalence was below 1 percent, they attribute the anomaly to statistical factors involving rare outcomes in relatively young cohorts.
Socioeconomic Advantages and Future Research
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Although the exact mechanisms remain uncertain, researchers suggest the extra year of schooling may have provided socioeconomic advantages by elevating school qualifications, income, and occupational status. Compounded over half a century, those benefits might offer protection against neurodegeneration even for high-risk individuals.
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,
says study co-author Leandro Carvalho, adding that understanding which interventions produce protective effects remains an important direction for future research.
