One in 20 people reading this will have a gene that increases the risk of Alzheimer’s disease 15-fold. This gene, called AP0E4, doubles someone’s risk. And having two copies of this gene, as some people do, increases the risk significantly.

However, experts say most carriers are able to ‘out-exercise’ their genetics, meaning that if they look after themselves, exercise and eat well, then their risks are reduced to a similar level to those without the gene.

Around 150 minutes of moderate exercise a week is needed: this includes cycling, swimming, power-walking or strenuous gardening.

It goes to show how we are so much more than our genes, and how environmental factors – such as how healthy a lifestyle we choose to live – influence our health in such an important way.