An extra school year modestly cuts dementia risk

In 1972, the United Kingdom raised the minimum school-leaving age from 15 to 16. This affected only students born after September 1, 1957, creating what researchers call a ‘natural experiment’. They linked birth dates to administrative health records and looked at dementia diagnoses in later life. The study was published in PNAS.

A small but meaningful reduction

The extra school year reduced the cumulative incidence of Alzheimer’s disease and related dementias (ADRD) by approximately 0.88%. The researchers note this reflects the measurable impact of just one additional year of education. Notably, the reform also appeared to reduce genetic risk for ADRD, which challenges the assumption that genetic susceptibility cannot be altered by environmental factors.

What drives this effect?

How education reduces dementia risk remains unclear. One widely discussed explanation is cognitive reserve: the idea that intensive brain use during developmental years makes the brain more resilient to later damage. However, other explanations are not ruled out. More education also tends to correlate with higher income, healthier behaviour, and better healthcare access. This study did not establish which of these factors is responsible. The researchers emphasise that dementia incidence can be modified through social policy, a finding with broad implications as case numbers are expected to rise sharply in coming decades.

Read the original article