A blood test designed to assess how well somebody is ageing could be used to predict whether or not they are likely to develop certain illnesses, like Alzheimer's disease.
Researchers based at King's College London took muscle-tissue samples from healthy 65-year-olds, and were able to identify 150 genes associated with healthy ageing. The activity of these genes working together, termed a 'gene signature', reliably distinguished whether somebody was young or old.
Lead author Professor James Timmons, said: 'We use birth year, or chronological age, to judge everything from insurance premiums to whether you get a medical procedure or not. Most people accept that all 60-year-olds are not the same, but there has been no reliable test for underlying "biological age".'
Using this procedure in a sample of 70 Swedish patients, the researchers noted that, despite being the same age, there were large differences in this gene signature. This gene signature was also present in other samples, including skin and brain tissue.
'Our discovery provides the first robust molecular "signature" of biological age in humans and should be able to transform the way that "age" is used to make medical decisions,' said Timmons.
Importantly, people diagnosed with Alzheimer's disease also had an altered gene signature. 'This is the first blood test of its kind that has shown that the same set of molecules are regulated in both the blood and the brain regions associated with dementia,' Timmons added.
However, an article published on the NHS Choices website argued that any firm conclusions about treatment or diagnosis would be premature, stating: 'Overall, the study is of interest, but it is too soon to suggest to the general public that they could have a blood test to determine their age and risk of types of dementia such as Alzheimer's.'
The research was published in the journal Genome Biology.