A new blood test reveals how well your body is ageing – and could also predict whether you’re likely to develop dementia.

You might think you look pretty good for your age, but it’s what’s going on inside your body that really matters, and now scientists have developed a simple test which estimates how quickly a person is ageing.

The test measures the vitality of certain genes and can, say researchers at Kings College, London, provide an accurate indication of biological age – which could be older or younger than actual chronological age – and may even help predict when you might die. The test looks for an ‘ageing signature’ in the body’s cells by comparing the behaviour of 150 genes.

‘Most people accept that all 60 year olds are not the same, but there has been no reliable test for underlying biological age until now,’ says lead researcher Professor Jamie Timmons.

Being told that your body is 85 whilst you’ve only just turned 69 might seem pointlessly depressing, particularly since there isn’t a lot you can do to change it (researchers admit they’ve found no clues as to how to slow down the ageing process). However, there’s far more to this test than morbid curiosity. For example, it could be used to identify those at greatest risk of getting Alzheimer’s or other forms of dementia years in advance and to enrol them in clinical trials.

‘This test should be able transform the way that ‘age’ is used to make medical decisions,’ adds Professor Timmons. ‘It raises a number of questions, no doubt, but we are judged by our age already, so this might be a smarter way of doing it.’

The test was warmly welcomed by many Alzheimer’s and dementia experts, though Dr Eric Karran from Alzheimer’s Research UK, warned it would need ‘rigorously validating to show it was accurate and sensitive before it could be used in the clinic.