Blood test 'could detect risk of dementia'

A blood test has been developed that could identify people at risk of dementia.

The genetic test - which can also show if people are ageing too fast - is the first to provide an objective measurement of "biological age".

This could allow medical professionals to see early signs of Alzheimer's disease and other forms of dementia, allowing patients to get better care and potentially aiding the search for preventative treatments for middle-aged people.

Lead researcher Professor James Timmons from King's College London said the test could be the first reliable measure of a person's biological age.

How does the test work?

Scientists analysed thousands of blood, brain and muscle samples to find 150 markers of gene activity linked to good health at the age of 65.

Using these, a score-based rating system was produced for healthy ageing that could be incorporated into a blood test.

More than 700 health 70-year-olds were given the test and were found to have a wide range of scores, varying by up to four times.

Higher scores were associated with better mental ability, kidney function and longevity over a 12-year-period, while low scores were linked to Alzheimer's.

What is biological age?

• While we all age at the same rate in terms of days, months and years, scientists believe our biological rates of ageing can differ greatly.

• In short, this means the rate at which the body and mind's functions are deteriorating.

• A recent study carried out in New Zealand used age-related "biomarkers" such as cholesterol levels, gum health and body mass index to identify the biological ages of more than 1,000 men.

• The result was that those found to have a higher biological age also had a higher pace of biological ageing - with both linked to poorer physical and cognitive function, as well as feeling less health and looking older.

• Currently it is unclear if anything can be done to slow the biological ageing process, but exercise, a good diet and keeping a healthy weight are all recommended as the best means of staying healthy for longer.