Using genetic information, researchers at Karolinska Institutet in Sweden provide new evidence that higher educational attainment is strongly associated with a lower risk of Alzheimer's disease.

The causes of Alzheimer's disease are largely unknown and treatment trials have been disappointing. This has led to increasing interest in the potential for reducing the disease by targeting modifiable risk factors. Many studies have found that education and vascular risk factors are associated with the risk of Alzheimer's disease, but whether these factors actually cause Alzheimer's has been difficult to disentangle.

Mendelian randomisation is a method that uses genetic information to make causal inferences between potential risk factors and disease. If a gene with a specific impact on the risk factor is also associated with the disease, then this indicates that the risk factor is a cause of the disease.

Susanna C. Larsson, associate professor at the Institute of Environmental Medicine at Karolinska Institutet, and colleagues in Cambridge and Munich, used the Mendelian randomisation approach to assess whether education and different lifestyle and vascular risk factors are associated with Alzheimer's disease. The analysis included more than 900 genetic variants previously shown to be associated with the risk factors. Comparisons of these genetic variants among 17,000 patients with Alzheimer's disease and 37,000 healthy controls revealed a strong association for genetic variants that predict education.

"Our results provide the strongest evidence so far that higher educational attainment is associated with a lower risk of Alzheimer's disease. Therefore, improving education may substantially decrease the number of people developing this devastating disease," says Susanna C. Larsson.

According to the researchers, one possible explanation for this link is 'cognitive reserve', which refers to the ability to recruit and use alternative brain networks or structures not normally used in order to compensate for brain ageing.

"Evidence suggests that education helps improve brain networks and thus could increase this reserve," says Susanna C. Larsson.

The study was financed by the European Union's Horizon 2020 research and innovation programme and the Swedish Brain Foundation.