“By pinpointing those who are beginning to lose their navigational skills, we hope to show that we can target people at a much earlier stage of the condition and one day become far more effective in treating them.”

The discovery that loss of navigational skills was associated with Alzheimer’s disease was made several years ago by Chan and colleagues based at several centres in the UK. These studies used tablet computers to test navigational tasks.

But now scientists plan to take their tests to a new level with the use of the virtual reality sets in which wearers are immersed in simulated environments through which they must navigate.

Around 300 people, aged between 40 and 60, will be recruited to take part in the study. Some will have a gene that puts them at risk of the condition or will come from a family with a history of Alzheimer’s. Not all will be destined to be affected by the disease, however. Chan’s project aims to find out who will.

Wearing virtual reality headsets, participants will be asked to navigate their way towards, and then remember details of, a series of different environments.

“We will make a note of those who have particular problems and see if these are the ones who are at higher risk of developing Alzheimer’s,” explained Chan. “The aim of the study is very simple: can we detect changes in brain function before people are aware that they have them?”

Researchers recently pinpointed the significance of a tiny area of the brain known as the entorhinal cortex, which acts as a hub in a widespread brain network that controls navigation. This now appears to be the first part of the brain that succumbs to Alzheimer’s.

“The entorhinal cortex is the first brain region to show degeneration when you get Alzheimer’s, and that is where we shall be focusing our research,” said Chan, whose work is funded by the Alzheimer’s Society.

The goal of the work is to help people as they develop the disease. “To date, drug trials for Alzheimer’s have been applied when people have already got dementia, by which time considerable damage to the brain has already occurred,” Chan told the Observer.

“If we can develop drugs and administer them earlier, for instance before the disease has spread beyond the entorhinal cortex, then this would have the potential to prevent the onset of dementia.”