A British law that kept teenagers in school until 16 created a rare natural experiment. Those who stayed the extra year were less likely to be diagnosed with dementia by age 65, especially people with a higher genetic risk. The researchers themselves say the size of the effect should be treated with caution.
Why this study is different
People with more education tend to get dementia less often. That alone doesn’t prove school is the reason, because richer or more stable families may give children both more schooling and better health. To get around this, researchers used a 1972 reform in England, Scotland and Wales that raised the minimum school-leaving age from 15 to 16. A strict birth-date cutoff meant that children born just after it had to stay longer than those born just before. It is almost like a lottery, and that is what makes the comparison fair. The NIH reports that it funded the study. According to HealthDay, the results appeared in PNAS. news-medical
What the researchers did
The reform increased the number of students staying in school until 16 by 14%. The team then looked at health data from more than 100,000 people in the UK Biobank, a large research database. They followed participants up to age 65 using hospital records, death registries and self-reported medical history. An extra year of secondary school lowered dementia diagnoses later in life +2
What they found
Those born just after the cutoff were less likely to be diagnosed with dementia than those born just before it. The researchers estimate that the extra year of school lowered Alzheimer’s and related dementia diagnoses over the following 50 years by 0.88%. They called this a considerable effect, because few people in the group had dementia at all. news-medicalnih
Genes played a role too. The link between genetic risk and later dementia was weaker among those who had to stay in school longer. In plain terms, the extra year seemed to soften the impact of a risky genetic background. newsofbahrain
Why the numbers need caution
Dementia is rare at age 65, and most cases appear later. Because participants were followed only up to 65, the differences between the groups could grow or shrink as the group gets older. The researchers described their estimates as imprecise. According to ScienceAlert, the team even acknowledges that the estimated effect looks implausibly large. nihnewsofbahrain
The study also can’t say what about the extra year helped. The researchers suggest it could be the socioeconomic advantages that more schooling brings. Science Alert
What it means
The findings suggest that investments made decades before symptoms appear, education among them, may influence dementia risk much later in life. This is an average result from one policy change, not a promise that one more school year protects any single person. As the participants get older, further follow-up should show how large and lasting the effect really is. news-medical
Source: An extra year of secondary school lowered dementia diagnoses later in life, NIH, October 23, 2026.
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