An extra year of school lowered dementia diagnoses decades later, a study of a 1972 UK reform finds

Staying in school one year longer lowered the chance of a dementia diagnosis decades later, according to a study funded by the US National Institutes of Health and published in PNAS on 23 October, NIH said. The effect was largest among people with a higher genetic risk of Alzheimer's disease.

A school reform as a natural experiment

Education and dementia have long been linked, but it has been hard to show that more schooling actually causes lower risk. A law in England, Wales and Scotland gave researchers a natural experiment: in 1972, the minimum school-leaving age rose from 15 to 16 for students born after 1 September 1957, and the share staying in school until 16 rose by 14%.

The team, led by researchers at the University of Wisconsin–Madison and the University of Southern California, compared people just affected and just unaffected by the reform among more than 100,000 participants in the UK Biobank. They drew diagnoses from medical histories, hospital records and death registries, up to December 2022, when the oldest participants turned 65.

A 0.88-point drop, larger for those at genetic risk

The extra year of school reduced the incidence of Alzheimer's disease and related dementias by 0.88 percentage points, which NIH called a considerably large effect given how low dementia rates were in this relatively young group. The signal was strongest for people carrying genetic variants known to raise dementia risk. The reform was also linked to better socioeconomic and other health outcomes, which may explain part of the effect.

“There are few preventative options out there so even one could make a world of difference.” — Silvia Barcellos, health economist, University of Wisconsin–Madison, lead author

What it means for people now

The study does not offer a treatment, and the participants were at most 65, so the gap between groups may grow or shrink as they age, the authors cautioned. Dementia affected 57 million people worldwide in 2021, with nearly 10 million new cases a year, according to the World Health Organization. NIA director Richard Hodes said the findings show dementia risk depends on factors beyond genes, and that additional schooling can offset inherited vulnerability. A UK trial is also testing several Alzheimer's drugs at once.