A blood test has been developed by scientists to assess peoples biological age as opposed to their chronological age.
The test, which measures how well a body functions on a genetic level, provides a better way to predict mortality and could have implications for the insurance industry.
The research, carried out by a team at King’s College London, found the test could identify people earlier who were at earlier risk of developing Alzheimer's and other age-related conditions.
Leading author James Timmons, also professor of precision medicine at King's College London, said current indicators used by life insurers to predict health and mortality such as age would not provide accurate results, because a large group of people of the same age could have dramatically different biological ages.
"We use birth year, or chronological age, to judge everything from insurance premiums to whether you get a medical procedure or not," he said.
"Most people accept that all 60 year olds are not the same, but there has been no reliable test for underlying 'biological age'."
The research, published in Genome Biology, involved the examination of 12 different studies and used samples of 150 genes in the blood, brain and muscle tissue of people from various age groups.
Timmons said: "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. This includes identifying those more likely to be at risk of Alzheimer's, as catching those at early risk is key to evaluating potential treatments."