Mass memory and reasoning tests 'track dementia risk'
A third of a million adults in the UK are to be invited to take part in the world's biggest study of cognitive function.
The aim of the trial, funded by the Medical Research Council, is to try to predict what factors may increase the risk of developing dementia.
All the participants will be part of UK Biobank, and previously gave DNA samples and lifestyle information.
They will be asked to do a series of memory and reasoning tests online.
When they were enrolled in UK Biobank over the past decade, volunteers gave blood and urine samples, underwent a fitness test and answered questions on their health and diet.
They also did a series of computer-based puzzles - those cognitive tests will now be repeated.
All the participants were aged 40-69 when the programme started.
This time the volunteers can do the test at home by logging in online.
Dr John Gallacher, an epidemiologist at Cardiff University. who helped devise the tests said: "Most people will have just minute falls in their test results since they did them last time but even this might help us predict who will develop dementia in the future."
Researchers will also look at other factors like smoking, diet and exercise, to see how big a factor these are in triggering dementia.
"It's important to stress that this is not a dementia test," said Dr Gallacher.
"In order to stratify people for dementia risk we have to know their cognitive function before they develop the condition."
UK Biobank, based in Stockport, is the world's biggest and most detailed biomedical resource.
Information about individual participants is anonymised, but open to researchers in any field provided they feed all their results back.
Another long term goal is to develop new treatments.
Dr Gallacher added: "If we could delay the onset of dementia by five years that would halve the number of people with the condition, which would be massive".
Dr Doug Brown, Alzheimer's Society Director of Research and Development said: "We know that changes in the brain happen decades before any symptoms of dementia present themselves.
"Studying people in mid-life could ultimately help us find clues to understand or even prevent the condition."